Control Philosophy Cover Sheet Rev 0 Revised

S. No DSC Comments WABAG Reply

1P&ID number to be indicated in the related documents

tableNoted and Complied.

2 Abbreviation to be corrected as "Motorized Sluice Gate" Noted and Complied.

3The (3W+2S) operating philosophy of the sewage

pumps to mentioned.

Noted and mentioned under the Sewage Pumping

System (4)

4Table for operation criteria based on Level to be

included.

Noted. The Level based pump operation cycle is

included under the heading 2.2.C

5 Add permissive condition for start of pump.Noted. The pump start persmissive conditions

included under the topic 4.3.1

6The (1W+1S) operating philosophy of the mechanical

screen to mentioned.

Noted and mentioned under "Screening &

Conveying System" (3)

7 Add Instrument Schedule

Please note that the Instrument Schedule is

submitted separately Vide the

Wabag Doc. No. 10P15-I0001-101

Client Doc No. DJB/P4/20/PS/I/801

8 Add Alarm ScheduleNoted. Alarm Level and Trip Schedule is enclosed

as annexure-1

9Add a small operation writeup indicating when gates and

other valves will Open/Close

Noted. The Valves/Gate operation table is

enclosed as annexure-2

10Add pumping station abnormal condition as per page no.

PS3B-17

Noted. The Pumping Station – Abnormal

Operating Conditions are listed under the topic

4.5

COMPLIANCE STATEMENT - CONTROL PHILOSOPHY COMMENTS

PREFACE

The objective of this document is to explain Process Control Philosophy for the Interceptor (Package-4) pumping

station under Delhi Jal Board.

M/s VA Tech Wabag is executing the total project and the plant operation is based on the control philosophy

explained in this manual.

VA TECH WABAG

Number11, Murray’s Gate Road, Alwarpet, Chennai - 600 018

PUMPING STATIONS, RISING MAIN AND ALLIED BUILDINGS OF

PACKAGE 4 - (RITHALA ROHINI)

ClientDoc No: DJB/P4/20/PS/I/815 Wabag

DOC No: 10P15-J0001-101

CONTROL PHILOSOPHYClient: Consultant: Consortium Partner

DELHI JAL BOARDM/s. ENGINEERS INDIA

LIMITEDM/s DSC LIMITED

Control philosophy for PUMPING STATION OF PACKAGE 4 - (RITHALA ROHINI) Page 2of 12

INDEX

I. LIST OF RELATED DOCUMENTS

II. ABBREVIATIONS

1. INTRODUCTION

1.1 PROCESS DESCRIPTION

2. GENERAL OPERATION PHILOSOPHY

2.1 MODES OF OPERATION OF PUMPS

2.1.1 Local Mode

2.1.2 Remote Manual Mode

2.1.3 Remote Auto Mode

2.2 DUTY / STANDBY/ CYCLIC OPERATION OF PUMPS

2.3 PUMP PROTECTION

2.4 MOTORISED VALVE OPERATION

3. SCREENING & CONVEYING SYSTEM

3.1 INTRODUCTION

3.2 INSTRUMENTATION

3.3 CONTROL SYSTEM & OPERATION

3.3.1 Timer mode

3.3.2 Differential Level Mode

3.4 ALARMS & INTERLOCKS

4. SEWAGE PUMPING SYSTEM

4.1 INTRODUCTION

4.2 INSTRUMENTATION

4.3 CONTROL SYSTEM & OPERATION

4.4 ALARMS & INTERLOCKS

5. ANNEXURES

5.1 Alarm Trip Schedule

5.2 Valve / Gate Operation Table

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I. LIST OF RELATED DOCUMENTS

Document No. Description

WABAG DOC NO. 10P15-D0015-101

CLIENT DOC NO. DJB/ P4/20/ PS/D/1200P&I DIAGRAM

II. ABBREVIATIONS

INSTRUMENTATION

LDT DIFFERENTIAL LEVEL TRANSMITTER

LE LEVEL ELEMENT

VS VIBRATION SENSOR

TS TEMPERATURE SENSOR

MS MOISTURE SENSOR

LDI DIFFERENTIAL LEVEL INDICATION

LDL DIFFERENTIAL LEVEL LOW

LDH DIFFERENTIAL LEVEL HIGH

LT LEVEL TRANSMITTER

LI LEVEL INDICATION

LALL LEVEL ALARM – LOW LOW

LAL LEVEL ALARM – LOW

LAH LEVEL ALARM – HIGH

LAHH LEVEL ALARM – HIGH HIGH

PI PRESSURE INDICATOR

PT PRESSURE TRANSMITTER

PAH PRESSURE ALARM – HIGH

PAL PRESSURE ALARM – LOW

FT FLOW TRANSMITTER

FR FLOW RECORDER

FQ FLOW TOTALIZER

FIC FLOW INDICATING CONTROLLER

LCP LOCAL CONTROL PANEL

ZSC POSITION FEEDBACK - CLOSED INDICATION

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ZSO POSITION FEEDBACK - OPEN INDICATION

GENERAL ABBREVIATIONS

MSG MOTORIZED SLUICE GATE

VFD VARIABLE FREQUENCY DRIVE

MGV MOTORIZED GATE VALVE

NRV NON RETURN VALVE

GV GATE VALVE

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1. INTRODUCTION

1.1 PROCESS DESCRIPTION

All dry weather flows intercepted from the sub drains by the interceptor chamber and conveyed to the

pumping station by the Interceptor Sewer, and pumped via rising mains to inlets of existing or new Sewerage

Treatment Plants (STPs).

The Sewerage collected in the inlet chamber will be conveyed to screen chamber through isolation gates. All

the major solid particles above 25mm size will be screened through mechanical coarse screen and the filtered

Sewerage will be collected in the wet well / pump sump. The collected Sewerage shall be pumped by

centrifugal submersible pumps and the sewerage shall be conveyed to the STP through rising main.

The operation and Control of each of the above units have been explained in detail covering the following

major points.

• Instruments as envisaged in the P & ID

• Control System, Interlocks & Operating sequence

• Alarm & Trip Conditions

2. GENERAL OPERATION OF PLANT

2.1 MODES OF OPERATION OF PUMPS:

All the Pumps installed in the plant can be operated either on Local mode from the Local Push Button Station

(LPBS) or from the HMI of PLC.

2.1.1 Local Mode:

In this mode of operation, any drive can be operated when the selector switch in the MCC/VFD

is selected for Local mode for operation. Once the Local mode is selected, the drives can be

operated only from the local push button station provided near respective drive. This mode is

generally provided for maintenance purpose only.

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2.1.2 Remote Manual Mode:

In this mode of operation, the selector switch in MCC/VFD has to be selected for Remote mode

of operation. Then the operator in the Control Room can select Manual mode from the PLC HMI

for enabling manual operation from HMI. In this mode all the Drives can be operated

individually and all the safety interlocks has been incorporated as envisaged in the control

philosophy.

2.1.3 Remote Auto Mode:

In this mode of operation, the selector switch in MCC/VFD has to be selected for remote mode

of operation. Then the operator in the Control Room can select Auto mode from the PLC HMI

for enabling Auto operation. In this mode all drives will be operated automatically in sequence

as per the Control Philosophy incorporating all the safety interlocks & permissive.

2.2 DUTY / STANDBY/ CYCLIC OPERATION OF PUMPS:

The duty / standby selection of the drives shall be done from the PLC HMI. The operator can select duty &

Standby pumps as per the process requirement and drive availability. The cyclic operation of Duty / Standby

drives ensures regular operation of all the drives at equal intervals. The cyclic changeover time can be

programmed from the PLC HMI and an alarm will be generated after each cycle time. The operator has to

change over from PLC. In view of any running pump getting tripped due to overload or any abnormal condition,

the next pump shall automatically take over if the process requirement permits next pump to run.

A. Two Pump Operation:

If there are two pumps, the operator has to change over the pumps on everyday basis after an elapse of 24

hours. An alarm is generated for pump changeover as a reminder for the operator. The alarm time is can be

preset based on requirement.

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B. Three Pump Operation

A typical cyclic table for the three pump operation is given below for reference.

Duration Duty Duty Standby

Day 1 PUMP A PUMP B PUMP C

Day2 PUMP B PUMP C PUMP A

Day3 PUMP C PUMP A PUMP B

C. Level based Pump Operation Table:

LEVEL INWET WELL

DUTY PUMPS

P1 P2 P3

HH ALARM & ALL PUMPS CONTINUE TO RUN

H3 RUN RUN START

H2 RUN START

H1 START - -

L3 RUN RUN STOP

L2 RUN STOP STOP

L1 STOP STOP STOP

LL ALARM & TRIP ALL PUMPS

Note: The above mentioned levels are adjustable values from the HMI of the PLC.

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2.3 PUMP PROTECTION:

The Pump will stop under the following conditions to ensure safe operation and Protection of Pumps:

• Tank level low-low.

• Discharge header pressure high-high.

• Discharge valve open feedback not available, within the specified time after the start of the pumps.

2.4 MOTORIZED VALVE OPERATION:

The motorized valves are interfaced to PLC and shall work on the following modes of operation.

• Local Mode

• Remote Manual Mode

• Remote Auto Mode

The following signals are available for each motorized valve in the PLC for monitoring & control purposes.

• Valve Open

• Valve Closed

• Emergency Stop button status

• Mains Failure

• Local Model Selected

• Overload Trip

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3. SCREENING AND CONVEYING SYSTEM:

[P&ID Reference: 10P15-D0015-101/ (DJB/P4/20/ PS/D/1204)]

3.1 Introduction:

The raw sewage from the interceptor sewers is collected in the Inlet Chamber [C-101]. The sewage is flow into

the two screening channels through the motorized gates [MSG-103/104]. The coarse particles will be removed

by the two mechanical screens [MS-101A/101B] and the collected waste is conveyed out by a Belt Conveyor

[BCR-101]. The belt conveyor [BCR-101] will function for both the mechanical screens. Two nos of Level

Transmitters [LDT-101/102] are provided in the upstream and downstream of each mechanical screen. The

screened sewage flows by gravity into the Wet Well Sump [WWS-101A/B] through the motorized gates [MSG-

105/106] respectively. The mechanical screens operate on a 1-Working; 1-Standby operating philosophy.

3.2 Instrumentation:

Level Transmitter [LDT-101/102]

3.3 Control System & Operation:

The mechanical screens and belt conveyors operate on the following modes of operation:

The Mechanicals Screen [MS-101A/101B] can be operated from its respective local control panels [LCP-MS-

101A/101B] in the local mode and from the PLC HMI in the remote mode of operation. The operator shall select

either one of the screens as Duty and the other one will be on Standby.

The mechanical screen will start by pressing the START PB configured on PLC SCADA screen. The operator shall

enter the differential level and time mode set points. The screen operates either on the differential level

demand or on the timer demand. The differential level demand will supercede even if the timer demand mode

is selected.

3.3.1 Timer Mode:

In this mode of operation, the screen & its belt conveyor operates for a fixed duration of time in fixed

frequency of operation. The duration and frequency of operation is adjustable through PLC.

3.3.2 Differential Level Mode:

In differential level mode, when the level differential gets high (H) across the mechanical screen, the

Mechanical screen and its Belt conveyor will start. The mechanical screen & its belt conveyor will stop when

the level differential gets low (L) or by pressing the STOP PB configured on SCADA screen.

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3.4 Alarms & Interlocks:

• Differential Level Transmitter [LDT-101/102]: The corresponding mechanical screens and the belt

conveyor will start in the Differential Level Mode when the value reaches a preset value [H].

• Differential Level Transmitter [LDT-101/102]: The corresponding mechanical screen and the belt

conveyor will stop when the value falls below a preset value [L].

4. SEWAGE PUMPING SYSTEM:

[P&ID Reference: 10P15-D0015-101/ (DJB/P4/20/ PS/D/1204)]

4.1 Introduction:

Five numbers of Sewage Pumps (SPW-101A/B/C/D/E) each with a capacity of 1728 m3/hr and a discharge

pressure of 3.4 kg/cm2 have been provided for pumping the sewage to the downstream STP through the rising

mains. The sewage collection sump has been divided into two separate compartments with an interconnecting

motorized operated valve (MSG-107). Normally this valve is kept in an open position.

In the first compartment, out of the two pumps (SWP-101A/B) either one of them can be selected for duty or

the other will be standby. In the second compartment, out of the three pumps (SWP-101 C/D/E) any two can

be selected as duty pump and the third one will be standby. The Sewage Pumps work on a 3-Working; 2

Standby operation philosophy.

4.2 Instrumentation:

• Pressure Transmitters [PT-101/102/103/104/105]

• Level Transmitter [LT-101]

• Level Transmitter [LT-102].

4.3 Control System & Operation:

The pumps SWP-101A/B are connected to a separate header and are provided with a Flow Transmitter (FT-101)

in the common header.

One pressure transmitter at the outlet of each pump has been provided for continuous monitoring of outlet

pressure of each pump and also for high pressure interlock.

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DOC No: 10P15-J0001-101





The pumps are VFD speed controlled based on the outlet flow. The operator can set the required flow value in

the PID control loop in the HMI of PLC. The actual flow output value is connected to this flow control loop.

Depending on the set point, the controller generates a controlled output for decreasing or increasing the speed

of the VFD.

At the outlet header of each pump a pressure transmitter has been provided for continuous monitoring and also

to trip the corresponding VFD, if pressure exceeds the set value.

The motorized On-Off valve provided at each pump outlet is normally kept closed before the start of each

pump. This action takes place automatically through PLC logic. When the start signal is given to the pump, the

corresponding motorized On-Off valve at the discharge end also opens. The pump trips if the open feedback

from the corresponding motorized valve is not available within the preset time delay.

4.3.1 Start Permissive for Sewage Pumps:

• The corresponding discharge valve is closed.

• The corresponding discharge valve available for operation (No trip condition)

• The corresponding common discharge valve is open.

• The pump available for operation (No trip condition)

• Level demand (level in the Wet Well reaches the operating level of the corresponding pump as per the

pump operation table) of the corresponding Sewage pump exists.

4.4 Alarms & Interlocks:

• Pressure Transmitter [PT-101/102/103/104/105]: Header pressure exceeds the preset value, the

corresponding sewage pump trips.

• Level Transmitter [LT-101]: The sewage pumps (SWP-101A/B) trips when Wet Well Sump (WWS-101A)

reaches low low level.

• Level Transmitter [LT-102]: The sewage pumps (SWP-101C/D/E) trips when Wet Well Sump (WWS-101B)

reaches low low level.

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4.5 Pumping Station – Abnormal Operating Conditions

• If any of the duty pump fails to start or trips during operation, the standby pump will start and the

alarm will be raised in the PLC – HMI.

• If the Ultrasonic Level Transmitter [LT-101/102] in the Wet Well fails, then all the duty pumps shall

continue to run and the alarm will be raised in the PLC – HMI

• If the PLC fails, all the pumps shall stop and will be operated manually through the push buttons

provided on MCC/LPBS by operator.

• On resumption of power supply after a power supply failure, the following sequence will be executed,

o The discharge valves will be closed.

o The pump normal start sequence will be followed

o During operation of the pumps, if the auto manual selector switch is changed from Auto to

Manual mode, the status of the pumps will not change. The running pumps will trip on the low

low level in wet well.

o During operation of the pumps, if the auto-manual selector switch is changed from Manual to

Auto mode, the duty pumps shall start according to the preset level programmed in the PLC.

o In case the discharge valve has to close after the pump has stopped and power supply is not

available, the valve will close on resumption of power.

o In case the start or stop sequence fails to complete, an alarm will be generated in the PLC –

HMI.

HH H L LL

1 PT-101 Sewage Discharge of sewage pump [P-101A]10P15-D0015-101DJB/ P4/20/ PS/D/1200

0 - 10 0 - 6 kg/cm2 AI TBA TBA TBA TBA

2 PT-102 Sewage Discharge of sewage pump [P-101B]10P15-D0015-101DJB/ P4/20/ PS/D/1200


3 PT-103 Sewage Discharge of sewage pump [P-101C]10P15-D0015-101DJB/ P4/20/ PS/D/1200


4 PT-104 Sewage Discharge of sewage pump [P-101D]10P15-D0015-101DJB/ P4/20/ PS/D/1200


5 PT-105 Sewage Discharge of sewage pump [P-101E]10P15-D0015-101DJB/ P4/20/ PS/D/1200


6 PT-106 SewageCommon discharge line of sewage pumps [P-101C/D/E] from Wet Well Sump [WWS-101B]

10P15-D0015-101DJB/ P4/20/ PS/D/1200


7 PT-107 SewageCommon discharge line of sewage pumps [P-101A/B] from Wet Well Sump [WWS-101A]

10P15-D0015-101DJB/ P4/20/ PS/D/1200


1 FT-101 SewageCommon discharge line of sewage pumps [P-101A/B] from Wet Well Sump [WWS-101A]

10P15-D0015-101DJB/ P4/20/ PS/D/1200

0 - 2500 0 - 2500 m3/hr AI TBA TBA TBA TBA

2 FT-102 SewageCommon discharge line of sewage pumps [P-101C/D/E] from Wet Well Sump [WWS-101B]

10P15-D0015-101DJB/ P4/20/ PS/D/1200

0 - 2500 0 - 2500 m3/hr AI TBA TBA TBA TBA

1 LE-101 Sewage Upstream of Mechanical Screen MS-101A10P15-D0015-101DJB/ P4/20/ PS/D/1200

0 - 4 0 - 4 m AI TBA TBA TBA TBA

2 LE-102 Sewage Downstream of Mechanical Screen MS-101A10P15-D0015-101DJB/ P4/20/ PS/D/1200


3 LE-103 Sewage Upstream of Mechanical Screen MS-101B10P15-D0015-101DJB/ P4/20/ PS/D/1200


4 LE-104 Sewage Downstream of Mechanical Screen MS-101B10P15-D0015-101DJB/ P4/20/ PS/D/1200


5 LT-101 Sewage Wet Well Sump (WWS-101A)10P15-D0015-101DJB/ P4/20/ PS/D/1200


6 LT-102 Sewage Wet Well Sump (WWS-101B)10P15-D0015-101DJB/ P4/20/ PS/D/1200


02. FLOW TRANSMITTER

03. LEVEL TRANSMITTER

NOTE :

1. All the alarm set points mentioned above are adjustable from the PLC-HMI2. TBA - To be Annouced later

IO Type

01. PRESSURE TRANSMITTER

Location

ANNEXURE - 1 (ALARM TRIP SCHEDULE)

Unit of Measure-

mentRemarks

Instrument Range In

P&ID No.Alarm Set Points

Tag No.S.No.Calibrated Range In

Process Fluid

SHEET NO. 1 OF 1

S.No Tag No. Location Open Condition Close Condition

1 MSG-101 Inlet to the Inlet chamber (C-101) Normally kept in open condition.

2 MSG-102 Overflow in the Inlet Chamber (C-101)Will be opened in the event of surges/overflow

from LPBS/PLCNormally kept in closed condition.

3 MSG-103 Inlet to Screening Channel (MS-101A)

4 MSG-104 Inlet to Screening Channel (MS-101B)

5 MSG-105 Outlet to Screening Channel (MS-101A)

6 MSG-106 Outlet to Screening Channel (MS-101B)

7 MSG-107Interconnection in the Wet Well Sump (WS-

101A/B)

This Gate will be opened when both the

Mechanical Screens are operated in the event

of surges/high inflow

Normally kept in closed condition.

8 MGV-101 Discharge of sewage pump [P-101A]

9 MGV-102 Discharge of sewage pump [P-101B]

10 MGV-103 Discharge of sewage pump [P-101C]

11 MGV-104 Discharge of sewage pump [P-101D]

12 MGV-105 Discharge of sewage pump [P-101E]

13 MGV-106Common discharge line of sewage pumps [P-

101A/B] from Wet Well Sump [WWS-101A]


101A/B] from Wet Well Sump [WWS-101A]


101C/D/E] from Wet Well Sump [WWS-101B]


101C/D/E] from Wet Well Sump [WWS-101B]

ANNEXURE - 2 (VALVE / GATE OPERATION TABLE)

The corresponding sluice gate will be opened

automatically depending on the duty selection

of the Mechanical screen from PLC

The other gate will be automatically closed

thro' PLC

The corresponding sluice gate will be opened

automatically depending on the duty selection

of the Mechanical screen from PLC

The other gate will be automatically closed

thro' PLC

When the start command is given to the

sewage pump, the corresponding discharge

valve will be opened automatically through PLC

command

Will be in closed condition when the

corresponding sewage pump is not running.


sewage pumps[P-101A/B] in Wet Well Sump

[WWS-101A] , these valves will be opened.


sewage pumps[P-101C/D/E] in Wet Well Sump

[WWS-101B] , these valves will be opened.

Will be in closed condition when the sewage

pumps [P-101A/B] in Wet Well Sump [WWS-

101A] are not running.

Will be in closed condition when the sewage

pumps [P-101C/D/E] in Wet Well Sump

[WWS-101B] are not running.

Control Philosophy Cover Sheet Rev 0 Revised

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