LevelstateLevelstateSystems Ltd.

7. Bentley Ind. Ctr., Bentley,

Farnham, Surrey. GU10 5NJ.

England. UK.

Tel : 01420 22818

Fax : 01420 22824

Boiler Water Level Monitor

202 System

INSTALLATION MANUAL

ISSUE: E March 2003

© 1992 Levelstate Systems Ltd. With technical progress the Company

All rights reserved reserves the right to change specifications

without notice.

Contents

Section Page

Boiler Codes or Standards - Summary of requirements 3

1 . Operating Principle 4

2. General Configuration 6

2.1 Trip Circuits 11

2.1.1 Low Level Trip 12

2.1.2 High Level Trip 13

3. Installation & Cabling

3.0 General 14

3.1 Water Column 15

3.2 System Cabling 18

3.3 Electronic Unit 21

3.4 Remote Display 25

4. Commissioning

4.1 Probes 27

4.2 Electronic Unit 29

4.3 Water Column 30

5. Maintenance & Fault Identification

5.1 Pressure Parts 32

5.2 Electronic Units 34

5.3 Fault Identification Procedure 35

6. Electronic Unit Descriptions

6.0 Electronic Enclosure 37

6.1 Discriminator & Display - PCB1 39

6.2 Supply & Relay - PCB2 41

6.3 Remote Display Unit 43

6.4 202 EDLI Parts List 45

7. System Specification 46

8. PED DIRECTIVE DOCUMENTATION 48

2

Figs Page

1.1 Sensing Element 4

1.2 Water Level Monitoring 4

1.3 Typical Water Conductivities 5

1.4 Switching Hysteresis 5

2.0 System Configuration 8

2.1 Side Arm Water Column 9

2.2 Probe Type 801 and 803 10

3.1.1 Water Column Installation Detail 16

3.1.2 Water Column Support Structure 17

3.2.1 System Cabling 19

3.2.2 Water Column Probe Cable Routing 20

3.2.3 Cable Gland Allocation 20

3.3 Electronic Enclosure Outline Dimensions 22

3.4 Remote Display Outline Dimensions 26

5.3.3 Fault Identification Procedure 36

6.0 Electronic Enclosure Layout 38

6.1 PCB1. Layout 40

6.2 PCB2. Layout 42

6.3 PCB3. Layout 44

3

Boiler Codes or Standards - Summary of requirements

ASME Boiler Code

Boilers must have one gauge glass. Above 400psi operation two gauge glasses shall be provided. For

boilers with safety valves set at or above 900psi two independent remote level indicators may replace one

of the two gauge glasses. If both remote indicators are in reliable operation the remaining gauge glass

may be valved off but must be maintained in serviceable condition. If gauge glasses are not visible to

the operator two dependable Indirect Indicators shall be provided. The lowest visible level of the

gauge shall be at least 2” above the lowest permissible water level where there is no danger of

overheating any part of the boiler. Each water gauge glass shall be equipped with a top and bottom shutoff

valve of through flow construction to prevent stoppage by deposits of sediment. Straight run globe valves

shall not be used. Connections from the boiler to the remote level indicator shall be at least 0.75" pipe size

including isolation valves. For gage glasses connected to the boiler the steam and water connections shall

not be less than I" pipe size. There shall be no sag or offset in the steam pipe and no part of the water

connection shall be above the point of connection to the gauge.

It is recommended that each boiler have two independent low water cut-offs. The permanent installation of

cutout devices for low water cut-offs should not be provided; temporary devices can be installed for

testing.

British Standard BS759. Part 1. 1984

Boilers shall have two independent gauge glasses each capable of being isolated from the boiler. One

water level gauge is permitted for boilers of less than 145kg/h evaporative capacity. For boilers with safety

valves set at or above 60bar in two independent manometric remote level indicators may replace one of

the gauge glasses. One gauge glass with its isolating valves shall be connected directly to the boiler.

Remote level Indicators which have been approved by an “Inspection Authority” may replace

gauge glasses. The lowest visible level of the gauge shall be at least 50mm above the lowest permissible water level

where there is no danger of overheating any part of the boiler. Steam and water isolating valves if straight

pattern globe type shall be mounted with the spindle horizontal.

The bore of steam and water connections shall be not less than 25mm, local to fittings not less than

20mm. The level gauges shall be mounted as close as is practical to the boiler shell or drum.

Automatic controls shall effectively shut off the fuel supply in the event of low water level.

There is a reasonable degree of commonality between the above requirements and this is generally

reflected in other National Regulations. Accepted or recognised standards must be used for the design,

material selection, welding and inspection of pressure containing components.

4

1. Operating Principle

The Levelstate 202 System is an ‘approved’ electronic alternative to the gauge glass providing a

significant improvement in accuracy, visibility, reliability and safety, enabling transmission of the water

level condition to a remote display and the application of alarm and control functions. It includes

connections for two separate Mains Supply inputs to achieve the ultimate security and reliability for the

indication and control functions.

The discrimination between water and steam is based on the significant difference in resistivity between

the two states over the saturation range. The sensing element is a Probe with an insulated tip inserted in

a side-arm water column FIG 1.1. If a voltage is applied to the tip, conduction occurs between the tip and

the inside wall of the column. The dimensions are selected to provide a resistance typically less than 0.1

Mega-ohms when the Probe is immersed in water, which results in a resistance greater than 5.0 Mega-

ohms for the steam condition. An electronic discrimination circuit is arranged to sense whether the Probe

resistance is less than 0.1 Mega-ohms representing water or greater than 0.1 Mega-ohms representing

steam. The detection level is dependent on water purity and boiler operating conditions.

With 14 Probes spaced vertically in a side-arm vessel attached to the boiler FIG 1.2 and with each Probe

connected to its own sensing and water/steam indication circuit a vertical display of 14 Green/Red

indicators provides sufficient resolution for the water level indication. The spacing between Probes is

chosen to cover the required Sight-Range.

Fig 1.1 Fig 1.2

5

Fig 1.3

Fig 1.4 below shows the relationship between boiler water resistivity (the inverse of conductivity) and boiler drum

pressure. The side-arm column purposely stimulates condensate flow and this flushing effect results in the column

water being purer than the water in the drum. As the pressure increases the water resistivity increases and it is

essential that the water/steam switching threshold lies above the side-arm water resistivity for the maximum boiler

pressure encountered. On the other hand it is advisable to use as low a resistivity switching threshold as possible to

render the system less susceptible to switching over due to moisture and water droplets.

6

2 General Configuration

The 14 probes are installed in a side-arm water column in two staggered vertical rows, numbered from the

bottom; the ODD numbered probes are located on one side of the column and the EVEN numbered

probes on the opposite side. A typical Water Column is shown in Figs 2.1 and two versions of Probe

shown in Fig 2.2.

Two printed circuit boards contained in an IP65 (NEMA 4X) wall mounted enclosure provide 14 discrete

water/steam discrimination circuits, LED display, relay alarm outputs, 4-2OmA output and terminals for the

connection of a Remote Display Unit. A Probe channel comparison or validation circuit is included

whereby any channel indicating a "water above steam" or "steam below water" condition illuminates a

yellow system fault indicator and initiates a relay contact output.

Generally the water column is aligned for Normal Water Level (NWL) located between Probes 7 and 8,

with the lower probes normally sensing water and the upper probes normally sensing steam. As the steam condition presents a high resistance to the sensing circuit which is indistinguishable from an

open circuit connection, two wires are used on the probe channels normally sensing steam; if either wire is

disconnected the sensing circuit indicates the water state thus declaring the fault. For the single wire

connection to the lower probe channels an open-circuit connection obviously indicates the steam state at

the channel output again declaring the fault.

For this standard arrangement a 22 core PTFE cable is provided for probe connections with the lower 8

Probes having a single wire connection and the upper 6 Probes having a two wire connection.

To avoid galvanic action at the probe and variations in sensing voltage due to changing electrolytic

potentials, an alternating voltage source is applied to the probe and the sensing circuit responds only to an

alternating waveform. Two low frequency oscillators are provided for the source voltage, one driving the

odd numbered channels and the other the even numbered channels. The voltage applied to the probe is

less than 6 volts, current limited to 50 microamps and presents no risk to personnel.

Collectively the discrimination or sensing channels may be set to one of three sensitivity selections for

water conductivity.

Each channel output drives a Green LED for Water detected or a Red LED for Steam detected and also

increments the 4-2OmA Transmission circuit.

Two alarm relays RL2, RL3 with integral delays, may be programmed to any channel except 1, 7 and 14. If

more than one channel is linked to the RL2 or RL3 delay circuit either channel will initiate the delay relay

action.

If a channel from 2 to 6 is linked and a channel from 8 to 13 linked to the same delay circuit the low

channel will initiate delay relay action when steam is indicated (Lo Alarm) and the high channel will

7

initiate action when water is indicated (Hi Alarm). This can provide a single alarm contact for a combined

Lo or Hi Level Alarm.

An additional two relays RL1, RL4 are included for instantaneous or delayed Trip action whereby an

extended 2 out of 3 Probe Channel voting logic is applied. RL1 is allocated to Low Water Level Trip and

RL4 to a High Level Trip.

Relay action can be selected for normally energised or normally de-energised depending on the

alarm/trip policy required.

A link-programming feature allows selected display LED’s to flash on initiation of Alarm relays RL2 and

RL3. Any illuminated Red LED (Lo Water Level) on channels 2 to 6 and any illuminated Green LED (Hi

Water Level) on channels 8 to 13 may be selected to flash when either RL2 or RL3 bus line is activated.

An identical linking facility is also provided to flash LEDs on the Remote Display Unit.

To achieve the highest operational integrity, provision is made for Two Separate Mains Supply inputs to be

applied. The DC output voltages from separate transformers are interconnected to 12V regulators so that

in the event of one Mains Supply failing the 202 instrument remains fully operational. Either Mains

failure is signalled through the system fault alarm. One regulator is allocated to supply the Odd numbered

Probe channels and the second supplies the Even numbered Probe channels. A third regulator

separately supplies the logic board and alarm circuits. All regulators are current limited to prevent

rupturing of the Mains fuses in the event of a short on the associated circuitry.

PROBE END CONNECTION ELECTRONIC END CONNECTION

Pure Nickel PTFE coated

5 or 10 METRE

22 core

NICKEL ring crimps for probe connection

Ferrule crimps for electronic connection

Type 202 22 core probe cable

9

FIG 2.1 Side Arm Water Column

The 202 System employs multiple Probes installed in a vertical Column, usually in two

diametrically opposite rows. Two types of Probes are available; one rated at 120bar which is

directly screwed into the Type 501 Water Column or, for ratings to 207bar a flanged type is

inserted into the Type 503 Water Column and retained by a clamp plate which is secured by

four studs and nuts.

Fig. 2.2 PROBES

Spiral wound Metaflex Gaskets

St. Steel / Supagraf

Thread M16 x 1.5

PROBE TYPE 801 Rating 150 Bar @ 343 C

PROBE TYPE 803Rating 207 Bar @ 370 C

PROBE TYPE 802Rating 207 Bar @ 580 C

Compression nut fitting

11

2.1 Boiler shut-down or trip circuits

Two low water level shutdown devices are a stipulated requirement in the Regulations for the protection of

steam raising boilers, Two remote level indicators may replace one gauge-glass; if a trip circuit is derived

from each remote level indicator system the requirements are satisfied.

For the practical application of shut-down systems the consequences of malfunction of the protection

circuit must be considered when deciding which method of implementation is the most appropriate. If a

relay is normally energised in the healthy state of the plant, supply failure or relay coil open circuit will

obviously induce a spurious trip; if the relay is normally not energised, supply failure or relay coil open

circuit prevents initiation of a required trip action. Similarly if a normally closed relay contact is used and a

wire disconnection occurs a spurious trip is initiated. If a normally open contact is used a wire

disconnection is not apparent and a trip requirement cannot be initiated.

The economics of Power Plant boiler operation dictates that spurious trips due to protection system faults

must be minimised and the required degree of shut-down system "availability" must be achieved by

duplication of protection devices. For other boilers perhaps the consequent hazards created impose the

policy that a trip requirement must always be actioned and the possibility of spurious tripping has to be

accepted.

The protection system policy must first be established and the duplication and interconnection of the trip

circuits organised to suit the requirements in terms of Reliability and Availability. When discussing

industrial equipment performance the mere mention of 'failures' evokes Murphy's Law. It must be

accepted that even with an extremely small failure rate of one in a million hours (probability of failing once

in 114 years) it could happen tomorrow, so however remote the probability the consequential effects of

failures should be considered.

For the 202 System the prime failures which affect reliability are the following:-

1. Mains supply source. It a highly secure instrumentation supply is available this should be used. If

two Water Level Indicators are fitted they should be supplied from separate mains supply sources.

The 202 Electronic Unit has provision for two separate Mains Supply inputs. In the event of one

Mains Supply failure the Unit remains fully operational.

2. Steam leaks from valves can cause level indication errors.

3. The prime failure of the Probe is to the 'water’ state due to the possibility of insulator

contamination caused perhaps by poor control of boiler water quality. The water column

intentionally stimulates condensate flow through the system to reduce density errors but this also

improves the water purity in the column preventing contamination. Failure of the pressure seal at

the ceramic insulator generally causes the water state to be indicated. For probes normally

immersed in water at the lower levels this failure is not apparent and is only discovered when a

low level occurs where a trip may be required. It is recommended that a test for this type of failure

is performed at least every 6 months.

12

2.1.1 Low Level Trip

For boilers many ‘Operating Guidelines’ or ‘Codes of Practice' recommend that for low level tripping

devices any equipment fault should initiate a boiler trip. This presumably applies to single element

devices and does not reflect the fault tolerant approach of multi channel devices or the duplication of

equipment.

With the prime failure mode of the Probe to the water state and, for the lower Probes, a wire

disconnection inducing the steam state, there is some confliction in conforming to the above 'Guidelines'.

For the 202 system a secure fault tolerant approach has been implemented whereby the basic 2 out of 3

arrangement has been modified to produce 4 Pairs from 4 Probe channels. Any one pair where both

channels indicate the Steam condition will initiate trip relay action . The pairings are chosen to counter the

possibility of a 12V supply regulator failing which would eliminate the respective odd or even numbered

channels from the circuit. A delay on relay action is also available with time period of 1, 5, 10 or 15

seconds. To satisfy the ‘Guidelines’ a normally energised relay with normally closed contacts should be

used.

Spurious trips will be initiated for the following remotely possible failures:-

(a) 12V Supply failure or relay coil open circuit.

(b) A disconnection in the wiring to the shutdown device.

To avoid these spurious trips the following circuit should be implemented where the relay is not energised

and a normally open circuit connection to the shutdown device is used:

The problem here is the possibility of missing a necessary trip action if faults (a) and (b) ever occur. If a

second water level indicator is fitted and supplied from separate Mains Sources and its relay contacts

separately connected to the shutdown device, the possibility of both systems failing simultaneously is so

remote that it can be discounted. Ideally two separate shutdown devices should be installed.

E

D

NO

NC

+12v

0v

Shutdown Device

RL1 Delay

1 , 5, 10, 15 Seconds

Logic 4 pairs form 4 channels

Select Trip @ Probe 2

or 3 1

2

3

4

Relay Energised – De-energise to Trip

E

D

NO

NC

+12v

0v

RL1Delay

1 , 5, 10, 15 Seconds

Logic 4 pairs form 4 channels

Select Trip @ Probe 2

or 3 1

2

3

4

Relay Energised – De-energise to Trip

13

2.1.2 High Level Trip

There are no 'Guidelines’ for high level trips as the risks involved are not as disastrous - except for

associated plant. However the 202 Unit also provides the security of a modified 2 out of 3 arrangement

for the high level trip. Here the channel output logic level is reversed compared with LLT; a 12V regulator

failing would induce a spurious trip so the pairings are chosen to avoid this problem. A delay action is also

available.

2.1.3 Alarm Circuits

Two relays RL2 and RL3 provide Alarm signalling and have integral delay action which can be set to 1, 5,

10 or 15 seconds. RL2 and RL3 may be connected for two separate Lo or Hi alarms or one Lo and one

Hi. More than one channel may be connected to each relay; this feature allows a configuration whereby a

Lo and a Hi Probe channel connected to one relay provides a single output contact for a combined Lo/Hi

Alarm.

NOTE: Internal Test Switches SW1,SW2 are provided to check operation of the electronic

circuits, if these are operated the Alarms and Trips would be Initiated. An internal Link

(RL) Is available to prevent relay action if SW1 or SW2 is operated, otherwise the Trip

Circuits should be disarmed externally before opening the 202 Enclosure.

If required the switches SW1 and SW2 may be disconnected by unclipping and removing the spring and

shorting contact. The plastic caps may then be replaced to prevent any possibility of shorting the fixed

contacts.

E

D

NO

NC

+12v

0v

RL1Delay

1 , 5, 10, 15 Seconds

Logic 4 pairs form 4 channels

Select Trip @ Probe 2

or 3 1

2

3

4

Relay Energised – De-energise to Trip

14

3.0 Installation - General For Boiler applications the installation must conform to the accepted Regional or National Standards.

Pipework connections must be welded, tested and inspected to the relevant procedures. Ensure that the

appropriate Regulations are adhered to and procedures documented.

A typical Water Columns installation is shown in Fig. 3.1.1 and 3.1.2 but special versions may be required

for particular applications. In all cases it is essential to achieve the minimum length of connecting

pipework to the water column to minimise density errors. This is caused by heat loss which produces a

temperature difference and therefore a density difference between the water in the column and the water

in the boiler or heat exchanger. In particular the lower water connection should be as straight as possible

with a slight downward slope from the column to achieve good water circulation, preventing the

accumulation of dissolved solids and avoiding the possibility of level indication errors. The top equalising

connection should project inside the boiler shell to prevent surface condensate cascading down the

pipework to the column, excessive water flow in the column causes a pressure drop resulting in level

indication errors. Both steam and water shell tappings should terminate internally away from localised

turbulence, which causes pressure differences, and therefore level indication errors.

The inclusion of isolation valves requires the assembly to be supported by the top suspension lug of the

column ensuring there is no differential expansion between the support structure and the boiler drum. Fig

3.1.2.

If a boiler low or high water level trip circuit is connected to the 202 Electronic Unit it is recommended that

all isolation valves are lockable in the open position and the drain valve lockable in the closed position to

prevent spurious tripping by inadvertent valve operation.

The 202 Electronic Unit enclosure is usually sited adjacent to the Water Column within a distance suitable

for the 4m (12') length of special high temperature PTFE cable supplied. If longer cable lengths are

required, terminate the PTFE cable in a suitable watertight junction box and extend with standard 22 core

stranded conductor instrumentation cable; ensure extension cable is protected from heat sources.

Siting of the 202 enclosure must consider adequate visibility of the display, the routing of other cables

away from heat sources and the minimum risk of damage from surrounding plant or activities.

15

3.1 Water Column - Installation - General Requirements

3.1.1 For boiler side-arm columns Figs. 3.1.1, 3.1.2 the support structure should be installed, the column

attached by the top suspension lug and, in most cases, aligned with the drum NWL between Probes 7 and

8, Fig. 3.1.1. The support structure should be sufficient to take the weight of the column plus steam and

water isolation valves, drain valves and pipework.

Parallel slide or gate valves should be used particularly for water side isolation as they allow full bore

opening without restricting water flow. Straight run globe stop valves shall not be used (ASME) but if

permitted by other codes they must be mounted horizontally as shown. If the 202 System low and/or high

water boiler trip circuit is used it is recommended that all isolation valves are lockable in the open position

and the drain valves lockable in the closed position to prevent spurious tripping by inadvertent valve

operation.

It is essential to ensure there is a continuous downward slope of at least 1:50 from the Water Column to

the Boiler Drum to enhance water circulation. (ASME Code: No part of this water connection shall be

above the point of connection at the Water Column. For the steam connection to the boiler there shall be

no sag or offset in the piping which shall permit the accumulation of water)

The column connections are profiled for butt weld fitting to pipework; if socket weld fittings are to be used

the 40º profile should be removed and the fittings supported to allow 2mm (0.08") spacing to the fully

seated position. After welding to documented procedures any temporary supports should be removed and

alignment to NWL checked prior to weld inspection.

Fit Guards to protect Probe seatings.

Lag steam and water pipework and valves.

Before commissioning install Probe Cable as shown in Fig. 3.2.2.

As a precaution ensure steam and water isolation valves are closed and drain valve open.

16

3.1.2 Water Column Installation Detail

Fig 3.1.1 Water Column Installation 1. The Water Column should be suspended such that there is no differential vertical movement

between the Boiler Drum and the Column. Generally a spring suspension should be provided where the spring rate includes column, isolation valves, drain valves and associated pipework.

2. The lower water connection to the Column must be above the level of the connection to the Drum to

prevent air locks. For the same reason the steam connection to the Column must be below the connection to the Drum. Preference should be given to the continuous slope of the water connection with no restrictions, to aid water circulation.

3. The water connection inside the Boiler Drum should avoid turbulence from down-comers, feedwater

inlets etc. The steam connection should protrude sufficiently (X) to avoid drum surface condensate flowing to the Column.

4. Procedures for site welding of pipework and valves must conform to the National or Accepted

Standards for boiler applications.

Sight Range

NORMAL WATER LEVEL

ISOLATION VALVES

ISOLATION VALVES

DRAIN VALVES

Maximum slope possible

Suspension Lug Hole Dia. 25mm

X

MINIMUM DISTANCE POSSIBLE TO SUIT SITE CONDITIONS. Distances greater than 2 metres cause indication errors due to reduced water temperatures

in water column

17

5. Connection pipework and valves should be lagged to prevent heat loss. 6. Guards should be provided to prevent accidental contact with the Water Column; these should not

restrict convection cooling of the Column. 7. Probes should not be fitted to the Column until mechanical installation and Drum cleaning

processes are completed.

Fig 3.1.2 Water Column Support Structure

18

3.2 System Cabling

Fig 3.2.1 shows the System Cabling requirements. Fig 3.2.2 shows Probe Cable Fixings on the water

column and Fig 3.2.3 Cable Gland allocation on 202 Unit.

A 4 metre (12') sheathed length of special 22 core high temperature PTFE cable is provided for Probe to

202 Unit connections. This cable is pre-formed for the standard vessel arrangement where NWL is

between Probes 7 and 8. For longer cable lengths a junction box and standard PVC multi-strand

instrument cable should be interposed in the run to the 202 Electronic Unit. The Water Column looming

has been arranged for the cable to be clamped on the right hand side with the ODD numbered Probes on

the left hand side and the EVEN numbered Probes on the right hand side. It is recommended that the

cables are taped to the 6mm (1/4") vertical Tie Rods using 12mm PTFE Thread Seal Tape (as used in

pipe sealing RS 512-238).

Cable for the Mains Supply, 20 Core Remote Display, Alarm and 4-2OmA circuits are fitted as required

using standard instrumentation cable through the 202 Unit Cable Glands as shown.

1

2

3

4

5

6

7

8

9

10

11

12

13

14

22

21

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

Gy/Bk

R

O

V

W

R/Bk

O/R

O/W

Gy/R

Gy/W

W/Bk

Bk

Br

P

Be

Gy

R/Be

R/W

O/Be

O/Bk

GyBe

W/Be

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

14

13

12

11

10

9

8

7

6

5

4

3

2

1

4

3

2

1

20

19

18

17

16

15

E N L L N E

TB2

TB1

TB6

TB7

TB4

TB5

NC

NO

RL1 C

NC

NO

RL2 C

NC

NO

RL3 C

NC

NO

RL4 C

NC

NO

RL5 C

4/20mA +

Output -

14

13

12

11

10

9

8

7

6

5

4

3

2

1

20

19

18

17

16

15

TB1

TB2

20251 - 20252

REMOTE

DISPLAY

UNIT

REMOTE

DISPLAY

CONNECTOR

TYPE 202 ELECTRONIC UNIT

MAINS INPUT

110240V 15VA

MAINS INPUT

110240V 15VA

ALARM / TRIP Relay & 4/20mA outputs

Br

P

Be

Gy

R/Be

R/W

O/Be

O/Bk

Gy/Be

W/Be

Bk

R

O

V

W

R/Bk

O/R

O/W

Gy/R

Gy/W

W/Bk

Gy/Bk

WATER COLUMN

& PROBES

22 Core Instrument cable

1 sqmm cores. Lmax 500m

1.5sqmm cores Lmax 750m

22 Core PTFE cable Assembly

Part Number: 2022818/Length

Mains 1 | Probe Cable | Relay Outputs | Remote Display | Mains 2

PG 13.5 PG 9 PG 16 PG 21 PG 13.5

Top Guard

Block

Lower Guard

Block

Fig 3.2.2 Probe cable routing on water column

Fig 3.2.3 Cable Gland allocation

Using cable clamps run odd and even cables either side of the column

Tie cables along cable tie rod

21

3.3 Installation of 202 Electronic Unit

3.3.1 Before installation remove the front cover assembly and PCB 2 with chassis plate from the

enclosure and store in a safe place. Refer to Figs 3.3 and proceed as follows:

1 . Open front cover by loosening the two top captive plastic screws.

2. Disconnect ribbon cable from PCB 1 by pressing the two ejection levers on PL3 in an

outward direction and ease out the plug/cable assembly. Press the two bottom cover hinge

pins inwards and remove the complete cover assembly.

3. Unscrew the four M6 Cap Head (5mm Key) fixings at the corners of the base unit and

remove PCB 2 and chassis assembly. Refit M6 chassis plate screws into corner inserts to

avoid loss.

SPRING HINGE COVER REMOVAL

3.3.2 Mount the base of the enclosure with cable glands downwards at the site chosen using 4 corner

fixing screws, M6 or 0.25".

Strip cable sheaths so that they do not project beyond the inside of the cable gland; PTFE Probe cable is

preformed for correct length. Insert cables through glands, trim ends to template supplied and fit crimped

ferrules where required.

Test cable continuity as required.

202FAULT

2

4

14

10

12

8

6

1

3

13

9

11

7

5

Levelstate

200 mm

Mains 1 | Probe Cable | Relay Outputs | Remote Display | Mains 2

PG 13.5 PG 9 PG 16 PG 21 PG 13.5

120 mm320 m

m178 mm

298 mm

Type 202 Electronic Unit

23

3.3.3 At a convenient time before Commissioning, programme the required mode of operation of the

PCBs as follows :-

PCB1 - Refer to Section 6.1.1.

1 . Remove thin glass fibre cover.

2. Solder split pad link (centre of PCB) for the selected channel outputs

corresponding to the required alarm levels (middle pad to LH pad for

operation of RL2 or middle pad to RH pad for operation RL3).

3. Solder the appropriate split pad link "F" for the selected LED to flash

indicating the alarm level.

4. Solder split pad links for the required Trip Levels on the 2 out of 4

Logic circuits applied to RL1 and RL4.

LLT, split pads either side of IC18: LLT

Middle pads to upper for trip level at Probe 3. ( 3 ( 3

Middle pads to lower for trip level at Probe 2. 2 2

HLT, split pads either side of IC19: HLT

Split pad not linked for trip at level 13.

Split pad linked for trip at level 12.

5. Solder split pad links for the time delay required on LLT (RL1), HLT

(RL4) and Alarms RL2 and RL3.

6. If Trip Circuits are applied and it is required to inhibit relay action when

Test Switches SW1, SW2 are operated, solder link split pad (RL) ∩∩∩∩

located at the bottom of the PCB. To inhibit Trips only, link RL and (R L)

remove D26, D28.

7. Solder split pad links S or W to the middle pad (top centre of PCB1) W

to define whether the "all steam" or "all water' state is to represent 4mA

the 4mA current output for the 4 to 20 mA transmission signal. S

8. The two sets of split pad links above PL1 and below PL2, Sa, Sb Odd No.Chs.

determine probe channel sensitivity and should only be made after

evaluation of system performance. With no linking the setting is for Sa Sb

conductivity greater than 2µS/cm, middle pad linked to Sb for greater

than 1µS/cm and middle pad to Sa for greater than 0.5µS\cm. Both Even No.Chs.

sets must be linked identically.

Sa Sb

(

Ch.O/P

RL2 RL3

F.Bus

Ch.O/P→

12

) 15 10 5 1

24

PCB2 - Refer to Section 6.2.1.

1 . Set the correct mains source voltage using jumpers provided. (fit two jumpers for 115V; one

for 240V as indicated).

2. Solder the split pad links D or E for the selected mode of operation of RL1 to RL4.

D = Normally De-energised - Energise to Alarm or Trip.

E = Normally Energised - De-energise to Alarm or Trip.

RELAY

D

E

25

3.4 Installation of Remote Display Unit 20251

This unit is intended for panel mounting with cut-out size 174mm x 67mm (6.85"x2.64") and panel

thickness to 6mm (0.25")

Before fitting, solder link the appropriate split pads ‘F’ as on the 202 unit, PCB1.

Method of fitting :-

1. Remove the rear cover by unplugging the terminal block and removing the four corner

hexagonal nuts.

2. Insert the bezel assemble from the front of the panel, fit the cover at the rear and tighten the

four hexagonal nuts.

3. Terminate the cable ends on the free terminal blocks and insert into Display Unit plugs. Clamp the

cable as shown in Fig 3.3 (a) or (b).

CABLE CLAMP

TB2

UNIT AND REMOTE DISPLAY LAYOUT

REAR ELEVATION

UNIT AND REMOTE DISPLAY LAYOUT

SIDE ELEVATIONREMOTE DISPLAY CUT-OUT

PANEL CUT-OUT

Max panel thickness 6 mm

174

mm

67 mm16

3 m

m

56 mm

24 mm8 mm 60 mm MIN FOR ACCESS

USES 1 x 22 CORE 1mm COPPER

Max 400 m

202

UNIT AND REMOTE DISPLAY LAYOUT

FRONT ELEVATION

72 mm

180

mm

FAULT

2

4

14

10

12

8

6

1

3

13

9

11

7

5

Levelstate

TB1

Stainless Steal rear cover with 4 x M3

fixings.

One 14 way and one 6 way cable connectors

TYPE 202 REMOTE DISPLAY

4.0 Commissioning

It is essential that Probes are not installed until acid or steam purging of the plant has been completed. The

water column may be valved off during this procedure or special Probe position blanking plugs can be

inserted (Part No. 80151 for 501 Water Column, or 80351 for 503,or 80251 for 502).

4.1 Probe Installation.

Caution : Handle Probes with care. Do not remove from packing until required for insertion. The

Probe insulators are high quality ceramic material which is liable to crack if subjected to impact - Do

not use if dropped!

Type 801 :

1. First clean the vessel seating recess ensuring it is dry and free from radial score marks. Do not

use any form of release coating or jointing compound on the seating face; the spiral wound

gasket has exfoliated graphite filler which does not stick to seating faces.

2. Use a Moly Disulphide anti-scuffing paste on threads avoiding contact with seating face and

Probe insulators.

3. Screw in each Probe and tighten. Do not exceed 7ONm (52 lb.ft).

4. Connect wires to Probe terminals, tighten knurled nuts using finger pressure only. Refit Guards

for Probe protection.

Type 803 :

1. Inspect the vessel seating recess ensuring it is clean dry and free of radial score marks. Clean

butting faces of Clamp Plate and Vessel.

2. Insert Gasket and Probe to Vessel and carefully fit Clamp Plate over Probe and Studs.

3. Apply a thin film of Copper or Molybdenum based grease to exposed ends of studs.

4. Fit nuts finger tight; adjust nuts to obtain clamp plate parallel to vessel face (approx.

1mm gap).

5. Set Torque Wrench fitted with 17mm A/F long socket to 2ONm.

Initially tighten each nut equally through

45º or subsequently where wrench

‘clicks' at torque setting, in the sequence

1, 2, 3, 4 until clamp plate is flush with

vessel face. If the torque wrench ‘clicks'

without nut rotation this indicates that the

Clamp Plate is not parallel to Vessel

Face; before proceeding adjust nuts for

parallel faces.

1

4 2

3

6. Set Torque Wrench to 25Nm and tweak each nut until the Wrench clicks at the torque

Limit.

DO NOT ROTATE WRENCH BEYOND THE POINT WHERE IT BREAKS (CLICKS)

DO NOT EXCEED 25Nm TORQUE SETTING

7. Connect wires to Probe terminals, tighten knurled nuts using finger pressure only. Refit Guards

for Probe protection.

Type 802 :

Inspect the Insert seating taper ensuring it is clean, dry and free of radial score marks. Use a

Moly Disulphide anti-scuffing paste on threads. Fit Probe and tighten retaining nut until Probe

body is just nipped, i.e. where it just cannot be rotated. Apply 27mm A/F long socket and

tighten by 1/6 of a turn.

29

4.2 Electronic Unit.

4.2:1 Fit chassis plate + PCB2 to base of enclosure

4.2:2 Fit cover + PCB1 to enclosure by springing hinges inwards before locating on base hinge

holes.

4-2:3 Connect ribbon cable to PCB1 via PL3 ensuring hinged retainers on PCB1/PL3 are first

hinged outwards.

4.2:4 Ensure mains cable is not live and connect separate mains supply to PCB2 / TBl and TB2

checking that mains jumper links are correctly installed for mains voltages (115v or 230v)

4.2:5 Do not fit other terminal blocks to PCBs at this stage.

4.2:6 Switch on Mains Supply. Depress SW1 Green Button and check that all Green LEDs

become illuminated. Release SW1 and depress SW2 Red Button and check that all Red

LEDs become illuminated.

4.2:7 Connect Probe wires to PCB1 by inserting TB2 and TB3. If the column is empty all Probe

channels should have Red LEDs illuminated. Short out each Probe in turn by touching a

wire between the knurled nuts and probe body and check that the corresponding Green

LED becomes illuminated.

In some instances condensation in the column or Probe assembly may cause the Green LEDs to be

illuminated which cannot be cleared until steam heating is applied to the column. In this case a check can

be made by disconnecting the wire on the Probe; when open circuit the Red LED should be illuminated,

when shorted to Probe body the Green LED should be illuminated. If two wires are connected to the Probe

these must be held together for the above test.

4.2:8 If a Remote Display is fitted, insert PCB2/TB4 and 5 and check correct illumination of LEDs

by operation of SW1 & SW2.

4.2:9 Insert PCB2/TB6/TB7 and check the various operation states of external alarm circuits etc.

by open-circuiting or shorting the relevant Probe wires as above.

4.2:10 If any problems arise during the above procedures check above connections and refer to

Fault Identification and Maintenance, Section 5.2.

4.2:11 It is advisable to keep the 202 Enclosure Cover closed at all times except for test and

maintenance. Generally plant locations have sulphurous atmospheres which in the

presence of moisture can cause serious corrosion problems with electronic equipment

particularly terminals and contact connections.

30

4.3 Water Column Bringing on-line.

4.3:1 Notify personnel of the intention to commission the Water Level Monitoring System.

4.3:2 Ensure Probe Guards are in place.

4.3:3 Close Drain Valves.

4.3:4 Slightly crack open the Steam Isolating Valve and observe by the Display that the column fills

slowly due to condensation (15 minutes +).

4.3:5 After 15 minutes crack open the Water Isolating Valve and check with Display that the water

level falls to the expected NWL in approximately 2 minutes.

4.3:6 Check valves and probes for steam leaks. Tighten probes if necessary. If steam issues

from the probe top insulator replace probe using Fault Repair Procedure Section 5.1

4.3:7 Open Water Isolation Valves fully.

4.3:8 Open Steam Isolation Valves fully.

4.3:9 The System is now operational. Where valve locks are fitted these should be locked if the

system is to remain in service:

Isolation valves locked in the OPEN position.

Drain valves locked in the CLOSED position.

The above method allows the Column to fill slowly and to be heated at a controlled rate and avoids

subjecting the Probes to any significant thermal shock which could adversely affect the pressure sealing

interfaces within the Probe assembly.

CAUTION: DO NOT BLOW-DOWN THE WATER COLUMN WITH PROBES INSERTED.

31

5.0 Maintenance and Fault Identifications

The following sections outline fault identification and rectification procedures. No routine maintenance is

required apart from periodic dusting of Probe external insulators using a small paintbrush to remove the

possible accumulation of flyash.

It is recommended in the interests of preventative maintenance that all Probes are replaced every 4 years,

or at least replace the lower Probes which are continuously immersed in water within 4 years as some

dissolution of the ceramic insulator does occur.

A check on the condition of the lower Probes normally immersed in water is recommended every six

months to ensure they correctly switch to the steam condition when the Water Column is drained. With

the system at operational temperature isolate Column, Procedure 5.1.3. When fully drained check that all

Probe channels indicate the steam condition (Red). If any channel indicates water (Green) check that the

Electronic Unit and Probe connections are functioning correctly by removing the Probe connection and

verify that the indication changes from Green to Red, in which case the Probe is faulty and must be

replaced. If a fault has occurred on the Electronic Unit rectify this first then replace the Probe connection

before determining whether Probe is faulty.

32

5.1 Pressure Parts

The large bore thin wall Water Column permits heat loss which stimulates condensate flow preventing the

build-up of sediment which obviates the need for vessel blow-down. As periodic blow-down is not

necessary the system reliability is enhanced due to reduced valve operation. The high purity condensate

keeps the Probes clean and the flow maintains the Water Column temperature near the Drum water

temperature which minimises density errors. Any flow restriction or pressure loss due to Valve or Probe

leaks can cause errors in water level indication.

If a serious Probe leak occurs the Water Column should be isolated immediately otherwise gasket seat

erosion may entail re-machining of the Column seating faces.

For damaged seat faces on the Type 501 and Type 503 Water Columns

For the 501and 503 Water Columns, re-cut seating face to an N8C finish which must be accurately

machined at 90' to the centre line of the opening.

5.1.1 Valve steam leaks - requires replacement of steam gland packing. Drain valves not sealing

properly requires seat replacement or re-grinding. Rectification should follow the normal

practices for the particular valve types.

5.1.2 Probe leaks - It is difficult to distinguish between Probe internal seal failure or Probe to

Column seal failure unless the leak is small. Steam emanating from the Probe top ceramic

insulator indicates internal seal failure and requires Probe replacement. Steam emanating

from the Column/Probe seating area may be rectified by further tightening of the Probe but

DO NOT EXCEED specified Probe tightening torque - otherwise replace Probe or gasket

using the following procedures.

5.1.3 Column Isolation Procedure

(i) Ensure Operators are informed that erroneous indications and alarms are to be expected.

(ii) If shutdown or trip circuits are connected to the system ensure they are disarmed.

(iii) Close the Steam and Water Isolation Valves.

(iv) Slowly open the Drain Valve(s) and leave open.

(v) Check at Drain outlet that the Isolation Valves are sealing properly.

33

5.1.4 Probe Replacement Procedure

(i) Isolate Column as 5.1.3 above, ensuring Drain Valve is open, with Steam and Water Isolation

Valves closed and sealing properly.

(ii) Remove Probe Guard and disconnect Probe wire(s).

(iii) Replace Probe as procedure Section 4.1 for Type 801 or 803.

5.1.5 Column Recommissioning Procedure

(i) Close Drain Valve(s).

(ii) Crack open the Steam Isolation Valve(s) and check with the display that the Column fills

slowly due to condensate (15 to 20 minutes).

(iii) Crack open the Water Isolation Valve(s) and check that the water level falls to the expected

level.

(iv) Check Probes for steam leaks using procedure of 5.1.2.

(v) After approximately 10 minutes fully open Water then Steam Valves.

(vi) Ensure all Valves are correctly set (and locked).

(vii) Inform Operators that the Indication System is now in service.

(viii) Check that approximately normal water level is displayed before rearming any shutdown or

trip circuits connected to the System.

The above procedure allows the Column and Probes to be heated at a controlled rate to prevent the

Probes being subjected to excessive thermal shock which could damage the ceramic insulators.

5.1.6 Column or Pipework Blockage

If the Column and pipework installation complies with recommendations of Section 4 and with the

intentional stimulation of condensate flow through the Column pipework blockage should not occur. This is

providing the boiler water treatment conforms to recommended practices such as ASME "Consensus on

Operating Practices for the Control of Feedwater and Boiler Water Quality in Modern Industrial Boilers" or

BS 2486 "Recommendations for treatment of water for land boilers".

If a partial blockage is suspected by the slow response times of the level indicator isolate the Water

Column as procedure 5.1.3. With the Drain Valve open slowly open the Steam Isolating Valve until there is

free flow of steam at the Drain outlet then close the Steam Valve. Slowly open the Water Isolating Valve

until there is free flow at the Drain outlet then close the Water Valve. Close the Drain Valve(s) and open

Steam and Water Valves. Ensure all valves are correctly set (and locked) and rearm trip circuits if fitted.

If the response time is still sluggish suspect problems with Isolation Valves not opening fully.

34

5.2 Electronic Unit Faults

Electronic faults can be diagnosed using the procedures for Fault Identification Section 5.3

If a circuit board is defective it is preferable to replace with a spare. For a local board repair ensure

precautions are taken to avoid STATIC as some components are MOS devices.

5.2.1 Check 202 Electronic Unit. Open enclosure cover by releasing the two top captive plastic

screws.

Depress Green Push Button SW1 at top of Display PCB (10 Seconds) - all Green LEDs

should be illuminated - no Reds.

Release SW1 and depress Red Push Button SW2 - all Red LEDs should be illuminated - No

Green.

If O.K. check for loose Probe connections to TB2, TB3 on PCB1.

Close enclosure cover.

5.2.2 Check Probe Connections. Remove Probe Guards. If channels indicating water oscillate

between Red/Green check Black & Grey/Black connections to bottom guard blocks or vessel

body.

Check Probe connections. (HOT? - wear gloves)

Channels indicating Steam (Red) - Apply a short circuit across the Probe top ceramic

insulator - Probe channel should change to Green.

Channels indicating Water (Green) - Disconnect wire from Probe, if two wires are fitted short

them together but isolated from column - Probe channel should change to Red. If this check

is O.K. but when wires reconnected to the Probe the Channel indicates Water when it is

judged to be in "Steam" by comparison with lower channels in Steam, suspect a faulty Probe.

Water cannot exist above Steam, unless the Probe is contaminated!

Refit Probe Guards.

35

5.3 Fault Identification Procedure

5.3.1 Fault on all Channels

5.3.1.1 Display Blank - Mains supply failure on both inputs

Fault signalled by external alarm - Fuse Fl and F2 ruptured

- PCB2 LED's illuminated - PL3 not

connected between PCB1 and 2 or

fault on cable or connector.

Switch off the Mains Supply before replacing fuse. If fuse has ruptured disconnect PL1 from PCB1 before fitting a replacement.

5.3.1.2 False all steam indication - O.V not connected to Water Column

- Column valved off and drained

5.3.1.3 Water indicated on upper channels - Probe connections open circuit

(2 wire connection) with steam - TB1, TB2 not inserted in PCB1

indicated on lower channels

(1 wire connection)

5.3.2 Fault on Alternate Channel Display Blank on Odd Channels - Regulator IC1 on PCB2 faulty.

Display Blank on Even Channels - Regulator IC2on PCB2 faulty.

Green LEDs illuminated - Oscillator fault IC1a for Odds, IC8b for

Evens

5.3.3 Fault on Single Channel 5.3.3.1 Neither LED illuminated - LED failure. TR2, TR3 faulty. R11,

R12 open circuit. Test as section

5.2.1 a (SW1 & SW2)

5.3.3.2 Water above steam indication (Fault indicated)

(i) The water indication is probably false if more than one channel immediately

below it indicates steam

(ii) The steam indication is probably false if more than one channel immediately

above it indicates water

(iii) If only one channel indicates water with only the one channel below it

indicating steam, either channel could be faulty.

CHECK:PCB1 by operation of SW1 and SW2 using procedure of Fig 5.3.3.

5.3.4 'Fault' Indicated - No S-W display fault.

Mains 1 or Mains 2 failure. Fl or F2 ruptured.

36

Fig 5.3.3 Fault Identification Procedure

37

6.0. Type 202 Electronic Enclosure, Fig. 6.0

The polyester glass-fibre reinforced enclosure with overall dimensions of 320 x 200 x 120mm is intended

for wall mounting using four M6 or 0.25" fixing screws through the corner apertures of the base external to

the cover sealing gasket. The cover has quick release hinge pins at the bottom and two

polyester/glassfibre screws at the top. Four cable glands are provided on the bottom face of the base

unit. Protection Rating for this enclosure is IP65.

The discriminator/display PCB is retained in the cover by the 6 screws, which secure the display bezel,

and by slot insertion along one edge. A thin glassfibre board provides protection for PCB1 components.

The clear laminated glass display window is sealed between the bezel and enclosure cover.

A metal chassis plate is secured to the base unit by four M6 screws. The supply/relay PCB2 is mounted

on the chassis plate and retained by eleven M3 screws and three M3 screws through the PTFE heatsink

supports. Terminals are provided for two separate 115/240V Mains Supply Inputs.

A 34 core flat ribbon cable which plugs into PCB1 interconnects the two PCBs.

The PCBs have been designed for long term reliability using the minimum number of components which

are significantly under-stressed.

Replacements for PCB Components is a delicate operation requiring special equipment to avoid

damage to static sensitive devices. To maintain operational reliability and security it is

recommended that spare boards are available and the faulty board returned to the manufacturer

for repair and test.

202

FAULT

2

4

14

10

12

8

6

1

3

13

9

11

7

5

Levelstate

Display Bezel & Window

PCB12022501

PCB12022501

Ribbon Cable connection

Fig 6.0 Electronic Enclosure Layout

39

6.1 Discriminator & Display. PCB1 Assembly No 2022501

This board contains the sensing circuits and display for 14 probe channels. Circuits are included for

channel validation, alarm and trip levels with delay action, 4 to 20 mA Transmission, display flashing and

push-button circuit test facility.

Channels 1 to 8 are "normally' servicing water and the source and sense are linked and a single wire

connection is made to the Probe. For Channels 9 to 14 'normally servicing the 'steam' condition, separate

source and sense connections are linked at the Probe to retain the lead monitoring feature. Any wire

disconnection induces the abnormal state at the associated channel sensing circuit so that the fault can

be detected and alarmed by the validation circuits.

Bu comparison with adjacent channels the invalid condition of 'Water above Steam' or ‘Steam below

Water’ can be detected. Additionally a supply failure from PCB2 is also applied to the validation circuits to

ensure detection of an equipment fault, this is annunciated by flashing of the display yellow LED and the

de-energisation of RL5.

The Odd Numbered Probe Channels are connected to PL1 and the Evens to PL2.

Solder split-pad linking is provided for the following functions:

1 Sensitivity selection for Water Conductivity. (Sa, Sb - odd and even channels)

2 Probe channel linking to Alarm Relays RL2, RL3

3 Trip Level selection

4 Alarm and Trip Delay Periods

5 Selection of Display LED Flashing at Alarm Levels (F)

6 The 4mA output of the 4/2OmA signal to represent ‘all water’ or ‘all steam’ condition

7 Inhibiting Alarm and Trip Relay action when Test Switches are operated (RL)

Two push-buttons SW1, SW2 provide a Test Water (Green Cap) and Test Steam (Red Cap) facility for

checking the electronic circuits.

Operation of SW1 or SW2 does not inhibit operation of relays RL1 to 4 unless split pad (RL) is linked.

F2

F3

F4

F5

F6

F8

F9

F10

F11

F12

F13

3

5

9

11

13

2

4

6

8

10

12

RL

Sa Sb

Connection to PCB 2||

Water Conductivity selection to be setAt site to suit operating conditions

Sa = Min. uS/cmNo Link = Max uS/cm

PL1 / TB 1

Odd Numbered Channels

Sa Sb

PL2 / TB 2

Even Numbered Channels

2022501 4/20mA

4mA=

All W

All S||

Lo & Hi AlarmsCh. Selection for

RL2 & RL3

TESTW SRL4RL1RL2

RL3

10 5 1

10 5 1 10 5 1 10 5 1

Delays: No linking = 15 Seconds approx

LL Trip / Alarm(validated)RL1

||

3

2

LL Trip / Alarm(validated)No Link=ch 13Link=ch 12RL4

||

3

2

| 12

Level AlarmsRelay: RL2 RL3

When 12 channel board then channels 11 & 10

Link for requiredRed LED to Flash(low water level)

Link for requiredRed LED to Flash(low water level)

Fig. 6.1 PCB 1 Layout

41

6.2 Supply & Relay. PCB2 Assembly No. 2022502

Each mains supply input is connected via a delay fuse to the primary windings of the transformer which

are either connected in series for 240v Mains input using a single jumper plug, or parallel for 115V Mains

input using two jumper plugs.

Each Secondary windings of the transformer is individually rectified by a bridge rectifier and the DC

outputs smoothed by a 2000µF electrolytic capacitor. Mains transient protection is provided and each of

the 4 DC outputs has an LED indicator L1 - L4.

Three 12V Regulators are provided to separately supply the following:

12VX Odd numbered Probe Channels

12VY Even numbered Probe Channels

12VZ Validation/Relay/4-20mA circuits. L5 LED.

Each regulator is supplied via transformers from Mains Supply 1 and Mains Supply 2 so that in the event

of a single Mains Supply failure the Unit remains fully operational.

PL3 provides connections between PCB1 and PCB2 via a ribbon cable.

TB4 and TB5 provides terminal connections for the Remote Display.

RL2 and RL3 are driven by associated time delay circuits on PCB1 and are intended for delay alarm

signalling.

R1 is allocated to a Low Level Trip and RL4 to a High Level Trip. RL5 provides output contacts for a

System Fault Alarm.

Relay circuits for RL1 to RL4 are identical, the input is normally at +12V; for Alarm or Trip conditions input

switches to 0.V. Linking solder pads D or E serve to define the state of the relay for normal or safe water

level conditions.

If a System Fault occurs RL5 de-energises signalling the Fault condition at the contact output, RL5 is

normally energised to enable initiation of System Fault if faults occur in the circuitry of RL5.

TB7 provides output terminal connection for the single pole changeover contacts of RL1 to RL5

TB6 provides output terminals for the 4-20mA signal.

RL1

RL2

RL3

RL4

E

D

E

D

E

D

E

D

D Link = Relay De-eng in normal state ( Energise to Trip)E Link = Relay Eng in normal state ( De-energise to Trip)

TB6 TB4

TB5

TB7 PL3

TB7/1

TB7/2

TB7/3

L N E E N LTB2 TB51

115V230V

MAINS VOLTAGE SELECTION250Ma ‘T’ 20 x 5 Fuses

F2 F1115

115

230

2022502

43

6.3 Remote Display Unit. 20251. PCB3 Assembly No 2022503

This separate DIN Size 180mm x 72mm display unit duplicates the 14 probe indications on the 202 unit.

Plugs 14 way and 6 way and associated cable terminal block sockets are provided at the rear with a cable

clamp facility.

The LEDs for the odd numbered channels are supplied from the 12V. X line TB2/20, and the even

numbered channels from the 12V. Y supply line TB2/18.

Solder split-pad linking is provided for the selection of Alarm Level Flashing of LEDs.

NB The row of green LEDs and the row of Red LEDs are each categorised for brightness to avoid

excessive differences in illumination. If replaced ensure correct category is selected.

F13

F12

F11

F10

F9

F8

F5

F4

F3

F2

F1

LY

LG LRD1

R3

R2 R1

R4 R5

Fig 6.3 PCB 3 Layout – Rear view

20

19

18

17

16

15

14

13

12

11

10

9

8

7

6

5

4

3

2

1

F6

45

6.4 202-EDLI Parts List

Description Part No

Detector PCB1 2022501

Supply Relay PCB2 2022502

PCB1 Fibreglass Cover 2023015B

Enclosure Base 2023011

Enclosure Cover Assembly 2022005

Chassis Plate PCB2 2023006C

Heatsink Support Bracket PTFE 2023016

Terminal Sockets TB1, TB2 BL11

Terminal Sockets TB4 BL14

Terminal Sockets TB5 BL6

Terminal Sockets TB6 BL4

Terminal Sockets TB7 BL15

Cable Gland PG9

Cable Gland PG 1 3.5x2

Cable Gland PG16

Cable Gland PG21

Mains selector Link MJO5

Mains Terminal Cover 2023009

Mains Fuses 20/250T

Probe Cable 4 metres 20228-04

Probe Cable 10 metres 20228-10

Installation Manual 2026900

46

202 Electronic Unit Specification

1 Electronic Level Indicator Unit. Type 202A

Enclosure:

Wall mounted glass-fibre reinforced polyester, IP65/NEMA4X protection for location in harsh

environments. Dims: 320mmH x 200mmW x 120mmD (12.6'x 7.8'x 4.7')

Inputs:

Discrimination between water and steam for 14 channels numbered in ascending order.

Discrimination threshold may be selected for minimum conductivity of 0.5 micro Siemens/cm, 1

micro Siemen/cm or 2 micro Siemens/cm.

The lower 8 Probe Channels have a single wire connection the Probe and the upper 6 channels

have two connections to each Probe. Any wire disconnection on the Probes reverts the channel to

steam indication if the Probe is immersed in water and any disconnection on the upper Probes

reverts the channel indication to water it immersed in steam. This facility enhances fault declaration.

A 4 metre (12') length of special high temperature PTFE cable is supplied for Probe connections.

For longer cable lengths connection to standard PVC cable advised, max. cable length 30 metres

(100’).

Display:

Two vertical columns of 10mm (0.4") square LED's provided on the front of the enclosure. One row

of Green LED's represents water and the second row of Red represents steam. Particular LED's

may be selected to flash on initiation of Alarm Relays. On channels 2 - 6, the Red LED (Lo Water

Level) and on channels 8 - 13, appropriate Green LED (Hi Water Level) may be programme to

flash. The flashing is initiated by alarm relay action.

A Yellow flashing LED signals a System Fault Condition

Supply Requirements: - Two independent AC sources

92 to 127Volts ) AC @ 15VA, 48 - 63Hz

or 184 to 254Volts )

The 202 Instrument provides improved operational integrity in the event of one Mains supply failure

by the method of implementing dc supplies to the electronic circuitry.

Temperature Rating:-

Ambient:- -10ºC to +65ºC, Storage : -50ºC to 100ºC

47

Outputs:

(1). Alarm Trip Relays. Four sealed relays, each having single pole changeover contacts provide Alarm

and Trip signalling.

Two relays provide low and high level alarms and each may be linked to Probe channels in the

range 2 to 6 and 8 to 13. A low and high channel may be linked to the relay for a combined Lo/Hi

alarm output.

The two Trip relays provide low level and high level trip initiation. For the trip circuits a 2 out of 3

Probe channel voting circuit is applied with a 4th channel backup to counter internal supply failure.

The normal LoTrip level may be selected for channel 2 or 3 and the Hi Trip level for channel 12 or

13.

Each relay may be programmed for the normally energised or normally de-energised state with a

delayed action period of 1, 5, 1 0 or 15 secs.

Contact Rating: Max. Current : 5 Amps.

Max. Voltage : 350 Volts

Max. Switching Power: AC - 600VA

DC - 3OW @ 110V

12OW @ 30V

(ii) Remote Display. Twenty terminals are provided for direct connection to a Remote Display Unit.

4/2OmA Signal: An integral circuit provides a 4 to 2OmA transmission signal whereby each

probe channel contributes a step change of 1.14mA. Selection of 4mA to represent the all water or

all steam state is included.

Output Current: 4 - 2OmA in 14 incremental steps

Load Impedance: 300ohms Max.

(iv) System Fault Alarm. A single pole changeover contact is available for signalling:-

(a) Supply failure.

(b) Probe channel malfunction by validation between adjacent Probe channels.

2. Remote Display Unit Option. Type 20251A

Panel mounted 180mm x 72mm x 30mm ( 7.1” x 2.83" x 1.2” )

Housing: IP20

This unit duplicates the display on the front of the main unit and is intended for control room

location.

Panel Cut-out Dimensions : 174mm x 67mm (6.85' x 2.64')

Panel Thickness: 1.5mm to 6.4mm (0.06'to 0.25’)

Page 1 of 1

Conformity Assessment for Manufacture of Water Columns to the PED (97/23/EC)

1. Pressure Equipment Classification Water Columns designed & manufactured in accordance with ASME B31.1 Power Piping and ASME B&PV Code Section 1 Power Boilers. (Not Code Stamped) Type 501E: Max Allowable Operating Pressure 150 bar Type 502: Max Allowable Operating Pressure 207 bar Type 503 Max Allowable Operating Pressure 207 bar Type Definition: - Pressure Accessories where the nominal size DN is more appropriate than volume. All DN sizes >32 but <100 Length of column where the volume becomes more appropriate:- For type 501E: 734mm For type 502: 634mm For type 503 582mm 2. Product Classification a). The state of the intended fluid contents: Gas b). The classification of the intended fluid contents: Group 2 c) Fluid type: Steam Therefore using Chart 7 in the Guidance Notes to give Category Assessment when DN is more appropriate: - Equipment Category 1 Using Chart 2 when the lengths of the columns are greater than shown above and volume becomes more appropriate:- Equipment Category II 3. Conformity Assessment Procedure From Equipment Category 1, the Conformity Assessment Procedure used will be: -

Module A: Internal Production Control

From Equipment category II, the Conformity Assessment Procedure used will be:-

Module A1: Internal Production Control with monitoring of final assessment

Justification of compliance with Essential Safety Requirements Levelstate Systems Limited Item of equipment : Water Columns Type 501E, 502 & 503 PED Category: II PED Module: A1 ESR N°

Subject

Justification

Justification of compliance with Essential Safety Requirements Page 1 of 2

0 – 3 Hazard analysis See Technical File & separate Hazard Analysis

1 Responsibilities to be clear for • Design • Manufacture • Checking • Installation (if applicable)

See Levelstate Specification 180031 issue A

1.1 Manufacturer’s instructions See Installation Manuals 1.1 Service conditions to be covered as reasonably

foreseeable

See Installation Manual for recommended practice and guidance

1.2 Approach taken to design Refer to Hazard Analysis

1.3 The potential for misuse See Installation Manual for recommended practice and guidance

2.2.1 Design for adequate strength - load factors

In accordance with ASME B31.1 Chapter II Part 1

2.2.3a Calculation method for pressure containment and loading

In accordance with ASME B31.1, ASME B&PV Code Sections 1 & VIII, Levelstate Design Spec 180031 Issue A

2.2.3b Calculation method for resistance In accordance with ASME B31.1 Chapter II Part 1

2.2.4 Experimental Design Method Not Applicable

2.3 Provisions to ensure safe handling and operation See Installation Manual for recommended practice and guidance

2.4 Means of examination ASME Code Section 1 PG 60 2.2 2.5 Means of draining and ventilating See Installation Manuals 2.6 Corrosion or other chemical attack See Installation Manuals. ASME B31.1 Calcs 2.7 Wear Not Applicable

2.8 Assemblies Not Applicable

2.9 Provisions for filling and discharge Not Applicable

2.10 Protection against exceeding allowable limits of pressure equipment

See Installation Manual for recommended practice and guidance. Water Columns to be fitted to pressurized steam systems protected by suitable devices.

2.11 Safety accessories In accordance with ASME B31.1 Chapter II Part 1 2.12 External Fire Not Applicable 3.1.1 Preparation of Component Parts ASME B31.1 Chapter V 3.1.2 Permanent Joining ASME B31.1 Chapter V ASME Section IX

3.1.3 Non-destructive testing Not Applicable

3.1.4 Heat treatment Not Applicable

3.1.5 Traceability ASME Section 1 & Levelstate Spec. 180031 issue A 3.2.1 Final inspection

In accordance with ASME B31.1 Chapter VI & Levelstate Specification 180031 Issue A

3.2.2 Proof test In accordance with ASME B31.1 Chapter VI &

ESR N°

Subject

Justification

Justification of compliance with Essential Safety Requirements Page 2 of 2

Levelstate Specification 180031 Issue A 3.2.3 Safety Devices In accordance with juridstriction Regulations by end-

user. 3.3 Marking and labelling

Nameplate detailed drawings

3.4 Operating Instructions Refer to Installation Manual 4.1 Materials suitable for duty Refer to Assessment of Suitability 4.2 a Material design Refer to Particular Material Appraisal

4.2b Which of the following options do materials comply with: • compliance with harmonised standards • European approval of materials • by a particular material appraisal

Refer to Particular Material Appraisal

4.2c For Categories III and IV, has material appraisal been done by the Notified Body

Not Applicable

4.3 Material documentation Refer to material Certification in accordance with EN10204 Type 3.1b or 3.1c

5a Appropriate protection of steam raising plant Not Applicable

5b Fluid sampling points Not Applicable

5c damage from deposits Not Applicable 5d Safe means of removal of residual heat after

shutdown Not Applicable

5e Avoiding dangerous accumulation of ignitable mixtures or flame blowback

Not Applicable

6a Pipework design (overstressing)

Installed by end-user

6b Pipework drainage Installed by end-user 6c Pipework turbulence and vortices Not applicable 6d Fatigue from pipe vibration

Installed by end-user

6e Group 1 fluids - take-offs

Not Applicable

6f Pipework - inadvertent discharge

Installed by end-user

6g Records of routing of underground piping for maintenance and repair

Not applicable

7.1 Allowable stresses In accordance with ASME B31.1 Chapter II Part 1 7.2 Joint coefficients In accordance with ASME B31.1 Chapter II Part 1 7.3 Pressure limiting devices. Not Applicable 7.4 Hydrostatic test pressure In accordance with ASME B31.1 Chapter VI &

Levelstate Specification 180031 Issue A 7.5 Material properties. Refer to Material Test Certification

Levelstate Hazard Analysis for the PED Equipment : Water Columns 501E, 502 & 5031) Determine which hazards are applicable for the pressure equipment.2) Determine if this hazard is reasonably foreeable for this equipment, for the use and design parameters specified.3) Determine how the hazard can be reduced / eliminated or what protective measures or notices will be given concerning the hazard.4) State whether if the hazard and the control measure used are acceptable and provide a high degree of health and safety protection.Ref. Hazard Reasonably Solution / Control Measure Acceptable ?No. Foreeable ?1 Explosion / Leakage of probes seats & Yes Use only on properly operated boiler with end users Yes

over heating - Hazard of stored energy correct operating procedures2 Brittle Fracture No Use only on steam raising plant. Yes

3 Damage instrument probes, freedom of Yes Use only on properly designed plant in accordance Yesvessel to expand, examination problems ? with juridstictions regulations and Inst. Manual

4 Damage to equipment - transport Yes Comply with Sect 15 of Quality Assurance Manual Yesor installation

5 Escape of PED Group 1 fluid - damage No Not Applicable Yesto persons, buildings, environment etc..

6 Rapid release of high pressure fluid Yes Water columns encased in steel shrouding. Yesprojection of vessel components / blast Refer to Inst.Manual for best positioning

7 Collapse, vacuum implosion - leakage No Due to rigid construction using forged components Yesof vessel / detachment etc..

8 Furnace explosion of fired vessels - No Refer to section 3 of Inst.Manual for best positioning Yesblast, projection of flame tc..

10 Domino or knock on effect - with No Items of inconsiquencial size on large boiler plants Yessubsequent damage to plant / property Refer to Inst.Manual for best positioning

11 Thermal expansion/pipework support Yes Refer to Inst.Manual for best positioning ensure Yes& vibration items fitted to properly designed sytem (i.e.B31.1)

12 Wind / Seismic / Snow / Transport / Cyclic / No Refer to inst. Manual for best practise YesExternal / Nozzle loading, Creep etc.. Items operate outside the creep range

13 Protective Device / Control system failure Yes Use only on propely operated steam systems Yes(response time / safe discharge / lockout) properly protected in accordance with Juridstn.Regs

14 Other - Specify : Yes Use only with properly treated boiler water as per YesCorrosion & Erosion Inst.Manual and allowances built into design calcs.

This document is provided for information purposes only. It is the manufacturer’s responsibility to ensure that they have considered all hazards that exist for their pressure equipment.

Further infor from CEOC guidance

Particular Material Appraisal in accordance with PED (97/23/EC) Part 4.2.b

Assessment of Suitability The materials used in the manufacture of the pressurised parts have appropriate properties for

aloperating conditions; in particular they are ductile and tough.

They are suitable for the steaming conditions of the boiler using feed water which is chemically

controlled and where corrosion is insignificant.

They have welding compatibility, as they are all low carbon alloy steels grouped by P numbers in

accordance with ASME B&PV Code Section IX.

They comply with the specifications of the ASME B&PV Code Section 1 PG 23 and ASME B31.1

Chapter IV Table 126.1

They conform to the requirements of ANNEX D of the PED (97/23/EC) Sections 2.2.3, 4, 4.1, 4.2

and 4.3.

They are supported by Inspection Reports in accordance with EN10204 type 3.1b & 3.1c.

An appraisal of each material used at the max operating limits of

700 degF /371 degC for low Carbon Steel & 1076 degF / 580degC for High Alloy Stainless Steel is

given in the table below.

The materials are purchased from a material manufacturer holding an appropriate Quality

Assurance System.

Material Specification ASTM

Ductile? Tough ? Weldability ? Suitable for High Temp ?

Certs reviewed ?

3.1b or 3.1c ?

A105 22% <0.25 % Carbon

Yes Yes 3.1c

A106 Grd B 22% <0.25% Carbon

Yes Yes 3.1b

A312 Type 316 22% <0.25%

Carbon Yes Yes 3.1b

Materials do not operate in brittle conditions Boiler Plant

Declaration of Conformity to 97/23/EC

Levelstate Systems Limited

7 Bentley Industrial Centre Bentley

Hampshire GU10 5NJ England

Pressure Equipment: Water Column Pressure Accessories used to

monitor steam/water levels in steam generating plant.

Type identification: 501E, 502 & 503 Equipment Category: Category II Conformity Assessment Procedure: Module A1 Notified Body: Royal & SunAlliance 17 York St, Manchester, UK Notified Body No: 0040 Technical Standards Used: ASME B&PV Code Section 1

Power Boilers ASME B31.1 Power Piping Authorized signature: ……………………………… Name: ……………………………… Position: ……………………………… Date of Signature : ………………………………

Absolute Temperature Specific Specific Latent heatPressure °C volume weight kJ/kg

Bar m³/kg kg/m³ of water of steam

20 212.37 0.09954 10.05 908.6 2797.2 1888.622 217.24 0.09065 11.03 931.0 2799.1 1898.124 221.78 0.08320 12.02 951.9 2800.4 1848.526 226.04 0.07686 13.01 971.7 2801.4 1829.628 230.05 0.07139 14.01 990.5 2802.0 1811.530 233.84 0.06663 15.01 1008.4 2802.3 1793.932 237.45 0.06244 16.02 1025.4 2802.3 1776.934 240.88 0.05873 17.03 1041.8 2802.1 1760.336 244.16 0.05541 18.05 1057.6 2801.7 1744.238 247.37 0.05244 19.07 1072.7 2801.1 1728.440 250.33 0.04975 20.10 1087.4 2800.3 1712.942 253.24 0.04731 21.14 1101.6 2799.4 1697.844 256.05 0.04508 22.18 1115.4 2798.3 1682.946 258.75 0.04304 23.24 1128.8 2797.0 1661.148 261.37 0.04116 24.29 1141.8 2795.7 1653.950 263.91 0.03943 25.36 1154.5 2794.2 1639.755 269.93 0.03563 28.07 1184.9 2789.9 1605.060 275.55 0.03244 30.83 1213.7 2785.0 1571.365 280.82 0.02972 33.65 1241.1 2779.5 1538.470 285.79 0.02737 36.53 1267.4 2773.5 1506.075 290.50 0.02533 39.48 1292.7 2766.9 1474.280 294.97 0.02353 42.51 1317.1 2759.9 1442.885 299.23 0.02193 45.61 1340.7 2752.5 1411.790 303.31 0.02050 48.79 1363.7 2744.6 1380.995 307.21 0.01921 52.06 1386.1 2736.4 1350.2100 310.96 0.01804 55.43 1408.0 2727.7 1319.7110 318.05 0.01601 62.48 1450.6 2709.3 1258.7120 324.65 0.01428 70.01 1491.8 2689.2 1197.4140 336.64 0.01150 86.99 1571.6 2642.4 1070.7150 342.13 0.01034 96.71 1611.0 2615.0 1004.0160 347.33 0.009308 107.40 1650.5 2584.9 934.3180 356.96 0.007498 133.40 1734.8 2513.9 779.1200 365.70 0.005877 170.20 1826.5 2418.4 591.9220 373.69 0.003728 268.30 2011.1 2195.6 184.5

221-2 374.15 0.003170 315.50 0.0

1 bar = 1.019716 kg/cm³

1 kg/cm² = 0.980665 bar

1 kcal/kg = 4.1868 kJ/kg

SATURATED STEAM TABLES(From VDI tables of constants of steam / water)

Enthalpy kJ/kg

2107.4

1 kJ/kg = 0.238845 kcal/kg

SpecifiedNominal Product Spec Grade Minumum -20 to 200 300 400 -20 to 500 600 650 700 750 800 850 900 950 1000 1050 1100Composition Form Number Class Tensile 100 400

C-Mn-Si Smls pipe SA-106 B 60.0 15.0 15.0 15.0 15.0 14.4 13.0 10.8 7.8 5.0 3.0 1.5

C-Si Forging SA-105 70.0 17.5 17.5 17.5 17.5 16.6 14.8 12.0 7.8 5.0 3.0 1.5

16Cr-12Ni-2Mo wld pipe SA-312 TP316 75.0 16.0 13.8 12.4 11.4 10.6 10.1 9.8 9.6 9.5 9.4 9.3 9.2 9.1 9.0 8.9 8.8

SA-106 Maximum operating temperature 370°C or 698 °F

SA-105 Maximum operating temperature 370°C or 698 °F

SA-312 Maximum operating temperature 580°C or 1076 °F

For Metal Temperatures Not Exceeding °F

multiply by 1000 to obtain psi

MAXIMUM ALLOWABLE STRESS VALUES FOR WATER COLUMN MATERIALS