Specs of Package Substation

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SPECIFICATIONS FOR 34.5 kV PAKAGE SUBSTATIONS

CONTENTS

1.0 SCOPE

2.0 DESIGN AND CONSTRUCTION REQUIREMENTS

2.1 System Characteristics

2.2 Package Substation Compartments / Components

2.2.1 Skid and Enclosure

2.3 Doors & Others

2.4 Transformer

2.5 Medium Voltage Termination Box

2.6 Ring Main Unit

2.7 Ring Switches

2.8 Circuit Breaker

2.9 Protective Relays

2.10 Interlocks

2.11 Earth Fault Indicator (EFI)

2.12 Low Voltage Compartment

2.13 Package Substation Foundation

2.14 Provision for Mobile Generator Cables

2.15 Name plate

2.16 Danger Plate

3.0 TESTING

4.0 SUBMITTALS

5.0 DATA SCHEDULE

5.1 Design and construction requirements

5.2 Package substation compartments/components

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1.0 SCOPE

This specification specifies the minimum technical requirements of design, engineering,

manufacturing, inspection, testing and performance of outdoor Package Substation (PS) intended

to be used in 34.5 kV systems.

A package substation combines power transformer, MV switchgear and LV distribution panel in

a single transportable unit ready for operation on being fixed in position on prepared concrete

foundation and connected to the power system.

2.0 DESIGN AND CONSTRUCTION REQUIREMENTS

2.1 System Characteristics

The Package substation shall be suitable for operation in system characteristics and including the

following:

MV neutral arrangement Solidly Grounded or Low Resistance

LV neutral arrangement solidly grounded

2.2 Package Substation Compartments / Component

2.2.1 Skid and Enclosure

2.2.1.1 RMU, Transformer MV termination box and LV compartment shall all be mounted on a

common galvanized steel skid.

2.2.1.2 RMU, transformer, MV and LV compartments shall all be provided with factory

assembled removable enclosure. The enclosure shall mechanically have arrangement to be de-

assembled / assembled at site / workshop technicians and by the use of normal / simple tools.

2.2.1.3 Enclosure and skid shall have adequate mechanical strength for lifting, mounting, and

transportation of the package substation as one unit. Lifting provision of package substation shall

be an integral part of the skid.

2.2.1.4 Enclosure shall be weatherproof, double roof and of robust construction and shall be

provided with watershed top. It shall be manufactured from galvanized sheet steel or aluzinc of

at least 3 or 2 mm thickness respectively.

2.2.1.5 Enclosure shall be provided with adequate ventilation for different components of

package substation to permit natural circulation of air. The ventilation apertures shall be screened

with galvanized / aluzinc double steel mesh to prevent entry of vermin and other foreign bodies.

The degree of protection of transformer compartment shall be IP-23.

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2.2.1.6 Enclosure and skid galvanizing / surface protection against corrosion, painting and finish

color (Cement gray RAL 7033).

2.3 Doors & Others

Access doors of LV compartment, transformer and RMU compartments shall be integrated as a

part of the enclosure body. These doors shall be hinged, press fit type gasketed and fitted with a

heavy-duty locking bar to secure it at the top and bottom. A central handle, locking bar, handle

integral lock and pad locking provision shall be provided. Locks and keys of LV and RMU

compartments shall be different from each other. However, the key of the RMU compartment

shall be suitable to open the lock of LV compartment.

All doors shall be provided with door stoppers and locking at open position to protect from

swinging in order to avoid accident.

All door hinges shall be concealed and made of stainless steel or brass.

All doors shall be bonded to the framework (enclosure) by a bolted removable 35mm2 tinned

copper braid.

All parts of equal size and shape shall be interchangeable. The general design shall be made with

minimum number of joints.

All insulating materials shall be non-hygroscopic and resistance to tracking.

All bolted electrical joints shall be secured by means of corrosion proof steel fasteners.

These fasteners (bolts, nuts, and washers) shall be galvanized.

All fasteners except the transformer shall not be accessible from outside of the enclosure of

package substation.

2.4 Transformer

2.4.1 Transformer shall be of suitable for package substation, outdoor ground-mounted type.

2.4.2 MV bushings shall be located horizontally on the right hand side (facing package unit from

the front) in a cable termination box. Bushing shall be suitable for M16 bolted type connection

with heat/cold shrinkable or pre-moulded termination with separable elbow connectors.

The bushing shall be fitted with a stud having an outer size of M12 for single hole flat pad lug

with 50-70 mm2 medium voltage cable.

2.4.3 MV and LV bushings shall be identified, labeled and printed with black paint as follows:

MV bushings: U V W

LV bushings: u v w n

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2.4.4 Oil level & temperature indicators and off-load tap changer operating knob shall easily be

accessible / readable and operate-able from LV panel compartment with adequate safety.

Oil temperature indicator shall be equipped with tripping contact if requested and specified in the

tender / data schedule.

2.4.5 Oil drainage / sample and pressure relief valves shall be included with the transformer and

shall be easily accessible from the transformer compartment.

2.4.6 Tap Changer:

2.4.6.1M.V.

Transformer shall be fitted with a lockable 5 positions, manual, offload

Tap Changer having the following taps:

Tap No. 1 +5% Of rated voltage

Tap No. 2 +2.5% Of rated voltage

Tap No. 3 0% Of rated voltage

Tap No. 4 -2% Of rated voltage

Tap No. 5 -5% Of rated voltage

2.4.7 Ratings:

All transformers shall be designed for secondary voltage of 400/230Volts.

The standard ratings shall be:

Skid mounted: 300, 500, 1000, and 1500 KVA

Transformer rated KVA shall be calculated on the following assumptions:

Constant flux regulation.

Continuous steady load.

50ºC average winding temperature rise and 45ºC top oil temperature rise limits above ambient.

Maximum winding hot spot temperature of 98ºC.

2.4.8 Losses:

2.4.8.1 Capitalization Formula:

Transformer vendors/manufacturers shall be evaluated by using the following capitalization

formula:

T = P + 11000 x C + 4000 x W

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Where T = Total capitalized cost in Saudi Riyals

P = Initial cost of transformer in Saudi Riyals

C = Iron (Core) losses in kW (No-Load Losses)

W = Copper (Winding) losses in kW at rated load (Load Losses)

2.4.8.2 Maximum Losses:

The indicated figures below are the maximum acceptable values.

Transformers with losses exceeding these values will be rejected.

Transformer Rating No-Load Losses

(Watts)

Load Losses

(Watts)

Up to 100KVA 250 1500

200kVA 380 2200

300kVA 520 3200

500kVA 750 4700

1000kVA 1100 9000

1500kVA 1700 14000

2.4.9 Guaranteed Values:

No-load and Load losses submitted in the tender shall be treated as guaranteed values. Any

increase in these values at the time of testing shall not be accepted.

2.4.10 Emergency Loading:

After thermal equilibrium has been reached at 75% of rated load, the transformer shall be

capable of sustaining the overload conditions listed in the following table without the

transformer winding hot spot temperature exceeding 140ºC:

Load percentage rating (%) Minimum Duration in Minutes at ambient temperature of

30o C 40o C

133 240 155

150 98 65

The supplier shall demonstrate by test and calculation that these requirements are met.

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2.4.11 Cooling:

Cooling shall be by natural circulation of oil internal to the transformer and external air i.e.

ONAN.

2.4.12 Transformer Oil:

Transformer shall be supplied initially filled of Class 1 uninhibited transformer Mineral oil

complying with IEC 60296.

2.4.13 Vector Group:

Unless otherwise specified, the transformer shall be connected delta-star in accordance with

vector group reference Dyn11.

2.14.14 Transformer Phase Rotation:

The contractor will coordinate with SEC related to the transformers phase rotation

2.4.15 Impedance Voltage:

The impedance voltage at normal tap shall be 4% for transformers up to 300KVA, 5% for

500 KVA and 6% for transformers greater than 500KVA.

2.4.16 Temperature Rise:

At the rated power the transformer shall comply with the following

Maximum temperature rises:

Top oil 45°C Max.

Winding 50°C Max.

Hot Spot 98°C Max.

Avg. temp. due to short circuit 250°C Max.

4.17 Noise Level:

The noise level emitted by a transformer, at full load, shall not exceed 48 dB.

Measurements shall be in accordance with IEC Standard 60551.

2.4.18 Short Circuit Level:

The short circuit current that transformer should withstand for two seconds is:

25 times full load current for ratings of 50, 100, 200, 300KVA

20 times full load current for rating of 500KVA

17 times full load current for ratings of 1000 & 1500KVA

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2.4.19 Skid-mounted transformer:

LV bushings/terminals shall be brought out of the transformer tank inside a cable box on the

opposite side of the HV box with cable entry coming vertically from bottom, box shall have

removable front and bottom sides.

The LV terminals shall be suitable to connect the following Copper cables:

Transformer rating

KVA

Cables per phase to

be connected

Cables for neutral

to be connected

300 & 500 one 1cx630mm² one 1cx630mm²

1000 two 1cx630mm²

1500 three 1cx630mm² two 1cx630mm²

2.4.20 Temperature Indicator:

A removable dial type thermometer shall be fitted in a thermometer pocket on the transformer

for oil temperature reading with a range 0-120ºC. The indicator shall be visible from ground

level.

2.4.21 Pressure Relief Vent:

A vent shall be provided to prevent rupturing of the transformer.

This shall be capable of withstanding the variations of pressure in normal service.

2.4.22 Oil Level Indicator:

An oil level indicator shall be fitted with the sight glass or dial type fitted to the same side of the

transformer as the tap change control handle. The indicator shall be visible from ground level.

2.4.23 Tank Earthing:

Two stainless steel M10 studs with nut and washer shall be provided diagonally opposite on the

tank for the skid mounted it shall be at the HV side of the transformer to facilitate tank earthing.

If the base assembly is detachable then the earthing facilities shall be located on the tank wall.

Suitable precautions shall also be taken to avoid corrosion attack on earthing facility.

2.4.24 Tank corrosion protection and finish:

i. The transformer tank and its accessories shall be adequately protected against corrosion.

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ii. Hot dip galvanizing followed by painting is the preferred method of base protection.

Otherwise tanks shall be shot-blasted and then immediately zinc sprayed to an average weight

deposit of not less than 550g/m², followed by zinc or zinc chromate based primary paint, and two

coats of durable oil and weather resisting paint. Finish color shall be Cement Grey, RAL 7033.

All bolts and fixings shall be suitably protected against corrosion.

2.4.25 Oil Drain Facility:

Facility for oil draining and filling shall be provided. The drainpipe size shall be one inch with

opening valve and sealing plug, the filling facility size shall be one inch with sealing plug.

2.5 Medium Voltage Termination Box

2.5.1 Medium voltage termination box shall be part of transformer.

2.5.2 Medium voltage termination box shall enclose cable clamps, grounding connectors and

medium voltage bushings.

2.5.3 Medium voltage termination box shall have adequate size for terminating three single core

or one three core MV cables. , sizes 50 to 70 mm2

Aluminum or Copper with heat / cold / pre-mold termination. This box shall be single gasketed

removable bolted cover. Bottom plate shall be in two halves and cable entry with steel knockouts

suitable for above cables. Loose rubber bushings shall be provided inside of this box for these

knockouts.

2.6 Ring Main Unit (RMU)

2.6.1 RMU shall be of indoor type. It shall be mounted on the common skid of package

substation on the right hand side to the MV cable box.

2.6.2 Earth Fault Indicator (EFI) shall be provided and installed at suitable location.

2.7 Ring switches

2.7.1 Ring switches shall be full load break and fault-making type. Ring switches shall be

designed for interrupting full rated current, small inductive or capacitive currents involved in

disconnecting of unloaded transformers, cables or overhead lines. It shall be suitable for full

fault-making current.

2.7.2 Ring switch shall consist of a moving contact assembly with three positions; ‘ON’, ‘OFF’,

and ‘Earth’. Two independent manual operating mechanisms for ring and earth switches are also

acceptable. The design shall prevent simultaneous closing of the main switch contacts and the

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earth switch contacts. The earth switch contacts shall be designed to close into a fault and shall

have the same short circuit capacity as the main contacts.

2.7.3 The switching operation shall be manual by means of an operating handle and independent

fast acting operating mechanism. Closing and opening speeds of the switch shall be independent

of the speed with which the operating handle is moved.

2.7.4 Ring switch operating mechanism shall have provision for on-site installation (retrofitting)

of geared motor mechanism and associated closing and opening coils with necessary contactors

for remote and future tele-control operations in the distribution network.

2.8 Circuit Breaker

2.8.1 Circuit breaker shall be withdrawable or fixed with insulation medium as SF6 gas.

The interruption medium shall be SF6 gas or vacuum.

2.8.2 Circuit breaker shall be designed to open, close and trip by local push buttons, remote

signals and tripping through protective relay circuit. Local and remote operation selection shall

be by a selector switch on the front panel.

2.8.3 Circuit breaker shall be provided with manual and electrical switching operation.

Geared motor mechanism for spring charging and associated closing and opening coils with

necessary contactors for remote and tele-control operations shall be included.

2.8.4 Earthing of circuit breaker shall be by means of a switch with same fault level capacity of

the breaker.

2.8.5 Operating mechanism shall be fast acting and independent of the operator action when

operating manually and shall indicate the following positions:

• Circuit breaker ON and OFF

• Off-Load Isolator ON and OFF

• Earthing ON and OFF

2.7.6 If circuit breaker panel equipped with an off-load isolator switch, it shall be fully

interlocked with the circuit breaker.

2.9 Protective Relay

Protective relay shall be AC self-powered, with built-in un-interrupted power supply, with over-

current and earth fault protection provided.

2.10 Interlocks

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Interlocks shall be provided to make the following operations impossible:

a) Operation of the ring switch or circuit breaker directly from “ON” to “Earth” or from “Earth”

to “ON”. The following additional requirements apply if the unit offered has two independent

manual operating mechanisms for ring and earth switches:

• Operation of the “Earth ON / Earth OFF” mechanism of earth switch unless the “ON/OFF”

mechanism of ring switch is in the “OFF” position.

• Operation of the “ON/OFF” mechanism of ring switch unless the “Earth ON /Earth OFF”

mechanism of earth switch is in the “Earth OFF” position.

b) Opening of the cable test cover without the associated ring switch being in the “Earth”

position.

c) Closing ring switch to “ON” with the test plug inserted and /or the cover open.

d) Insertion or withdrawal of the test plugs with the switch in any position other than “Earth”

position.

e) Opening of cable boxes without the associated ring switch or breaker in the “Earth” position.

f) Opening the off-load isolator switch (if any) unless the circuit breaker is in OFF position.

g) Closing the off-load isolator switch (if any) with the circuit breaker in ON Position.

2.11 Earth Fault Indicator (EFI)

Earth fault indicator shall be supplied. EFI shall be protected inside separate sunshield cover

with a mesh front (drawn from the same metal sheet). EFI shall be installed on the left-hand side

line-feeder. Three-pin socket for testing of EFI by primary current injection shall be provided in

separate compartment with screwed cover, below the EFI housing. SEC may require supplying

the EFI loose in an outdoor box for installation on masonry wall.

2.12 Low Voltage Compartment

2.12.1 Low voltage compartment outgoing circuit breakers shall be sized based on the maximum

demanded load.

2.12.2 Low voltage circuit breaker numbers shall be designed based on the load requirements.

2.12.3 As an option if requested in the tender, LV Panel for bulk power supply shall be equipped

with main circuit breaker without outgoing MCCBs and provision for direct connection of

customer cables on the bus-bar.

2.13 Package Substation Foundation

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Prefabricated steel reinforced concrete foundation shall be used for the installation of package

substation. This foundation shall be unified suitable to accommodate 300, 500, 1000 and 1500

kVA package substation.

2.14 Provision for Mobile Generator Cables

2.14.1 Two gasketed openings of 250 mm x 250 mm for the generator cables on the front and

sides shall be provided. These openings shall be provided with M8 size, round, non-slotted

bolted cover with nuts and washers. Unbolting of these covers shall be accessible from inside of

the package substation only. The gasket of these opening shall be pressure fit type.

2.14.2 Two (2) holes up-to 500 KVA and four holes (4) exceeding 500 KVA package substation,

each 13 mm diameter for installation of mobile generators cables shall be provided on the left

hand side (facing the package substation) vertically extended LV busbars.

2.15 Name plate

Aluminum name plates for the transformer and the low voltage compartment with the

information required and including item identification and PO numbers for the package

substation and shall be fixed inside the left door of the low voltage compartment.

Each transformer shall be fitted with a rating plate of weatherproof material, fitted in a visible

position, showing the information listed below. Etching, engraving or stamping shall legibly

mark entries on the plate.

Manufacturer’s name -

Manufacturer’s serial number -

Owners serial number (to be applied by SEC) -

Year of manufacture -

Specification - IEC 60076

Number of phases - 3

Rated power - KVA

Rated frequency - Hz

Rated voltages - kV

Rated currents - A

Connections symbol (Vector Group) - Dyn11

Impedance voltage at rated current - %

Resistance - ohm

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Type of cooling - ONAN

Total mass - kg

Total mass of core and windings - kg

Volume of oil - Liter

Connection diagram -

Table giving tapping voltages of the tap positions -

Ambient temperature - ºC

Purchase order no. -

2.16 Danger Plate

Danger plate shall be provided and installed on the front of the package substation using M5 hot

dipped galvanized /stainless steel / brass fasteners (oval head rounded neck bolts with nuts and

external tooth lock washers) not removable /accessible from the front i.e. without opening the

door / front cover.

3.0 TESTING

3.1 Complete type and routine testing of Package Substation shall be carried out as per IEC

61330.

3.2 The acceptance criteria for the Package type Substation shall be based on Class 10 (for

measurement of transformer temperature rise in an enclosure - IEC 61330).

3.3 Type (Design) test

3.3.1 The enclosure /frame shall be capable of carrying short circuit forces due to 40kA (rms)

symmetrical fault for one second

3.3.2 Temperature Rise Test

The temperature rise test shall be conducted as per IEC 60439-1

3.3.3 In lieu of the actual design (type) tests, certified test reports of design (type) tests

performed at an independent and reputed testing laboratory on an identical unit shall be

submitted to the owner for review and approval.

If design (type) tests on identical unit are performed at the manufacture’s test laboratory, these

tests shall be witnessed by Royal Commission representative.

3.4 Routine (Production) Test

All routine (production) tests prescribed in the relevant IEC or equivalent ANSI/IEEE standards

shall performed on all units

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4.0 SUBMITTALS

4.1 The vendor shall complete and submit filled-in data schedule and clause-by-clause

compliance sheet.

4.2 The following dimensional drawings and associated information shall be provided with the

quotation for each package substation rating:

4.2.1 Outline of package substation showing position of fittings, attachments and mounting

arrangements

4.2.2 Details of RMU, Transformer, MV termination box and LV Compartments

4.2.3 Single line diagram of package substation with all electrical components

4.2.4 Details / catalog of the following:

i. Skid layout and mounting arrangement

ii. All fittings & attachments

iii. Enclosure parts, gates & assemblies

iv. Fixing arrangement of LV MCCBs

v. Hardwood cable clamps

vi. Nameplate information

4.2.5 Mounting and installation details of package substation installed on pre-fabricated concrete

foundation

4.2.6 Comprehensive list of recommended spare parts with complete details including drawings,

catalog number / part number, manufacturer / supplier name of each item shall be submitted

4.2.7 Copy of type test report

4.2.8 List of customers in case of new manufacture / vendor

4.2.9 Details of manufacturing and routine test testing schedules (after signing of purchase order)

5.0 DATA SCHEDULE

5.1 Design and Construction Requirements

1. Nominal voltage 34.5/0.4kV

2. Nominal Package S/S rating 300 kVA, 500 kVA, 1000 kVA, 1500 kVA

3. Number of Distribution units based on design drawings

4. Main breaker requirement Yes / No ( )

5.2 Package Substation Compartments/Components

1. Length, mm

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2. Width, mm

3. Height, mm

4. Length of MV termination

5. Center to center distance between HV bushings, mm

6. Horizontal clearance between the outer MV bushing(s) and the inside of the

MV compartment, mm

7. Space between MCCBs, mm 10

8. Phase bus-bar current rating,

9. Phase bus-bar size, mm

10. Neutral bus-bar current

11. Neutral bus-bar size, mm

12. Oil temp. Indicator with trip Yes / No

Finish of enclosure

Finish method

Finish color

Cement Gray

RAL 7033

Transformer

Temperature indicator with tripping contacts requirement Yes / No

Provision for Generator Cables

Diameter of hole on the bus-bar, 13

Number of holes on each phase bus-bar 4 each for 1500kVA & 1000kVA

2 each for

500kVA & 300kVA

2. Number of holes on neutral bus-bar

2 each for

1500kVA & 1000kVA

1 each for

500kVA & 300kVA

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Ring Main Unit and Circuit Breaker

Description Specified Value Vendor Proposed

Values

1 General

1.Design Metal-Enclosed

2.Type In Package

enclosure

3.Number of cubicles 3 or 4

4.Insulation medium SF6

5.Rated voltage (nominal) 34.5kV

6.Maximum operating voltage 38kV

7.Rated frequency 60Hz

8. Rated Current 400A

9. Short circuit withstand current

for 1 second

21kA

10. Basic insulation level BIL (kV

peak)

170

11. Impulse Withstand Voltage 170-200kV

12. Power Frequency Withstand

Voltage (1 min.) kV rms

70-85 kV

13. Internal Arc fault withstand for 1

second

25kA

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2 Circuit Breaker

1. Type Fixed

2. Insulation medium SF6

3. Interruption medium SF6

4. Rated Voltage 34.5kV

5. Maximum Operating Voltage 38kV

6. Rated Frequency 60Hz

7. Rated Current of CB 100A

8. Rated Short circuit level (1 s) 25kA

9. Operating Mechanism Spring Charged

10. Protective E/F & O/C relay yes

Specs of Package Substation

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