rec specifications

SPECIFICATION FOR LINE SPECIFICATION FOR LINE MATERIALS AND EQUIPMENTMATERIALS AND EQUIPMENT

K.GOPALA KRISHNA

ACSR conductors for OH lines Outdoor conventional Distribution

Transformer 11 KV porcelain insulators and fittings LT porcelain Insulators and fittings 33/11 Kv Power Transformers 11 KV Lightning Arrestors Outdoor Type 11 KV/433V sealed

Distribution Transformer

33 KV vacuum/SFG-Circuit breakers 33KV OH.Porcelain Insulator fittings Single Phase Distribution Transformers 33/KV Lighting arrestors 11 KV vaccuum circuit breakers Aerial bunched cable for LT lines Aluminium alloy conductor for OH line 11 Kv Air break Switches 11 kv XLPE cables

Hard Drawn stranded Aluminum and Hard Drawn stranded Aluminum and steel-cored Alluminum conductor for steel-cored Alluminum conductor for OH LinesOH Lines

Specification : • REC Specification1/1971(revised 1993)• IS-398 Part I 1976(for AAC)• IS-398 Part II(for ACSR)

Scope - 33 KV Lines :

• ACSR 7/3.35 mm (500mm2 Al.area)• ACSR 7/4.09mm(80mm2 Al.area)• ACSR 6/4.72+7/1.57(100mm2 Al.area)

Hard Drawn stranded Aluminum and Hard Drawn stranded Aluminum and steel-cored Alluminum conductor for steel-cored Alluminum conductor for OH LinesOH Lines

Scope - 11 KV Lines :

• ACSR 7/2.11 mm (20mm2 Al.area)• ACSR 7/2.59mm(30mm2 Al.area)• ACSR 7/3.35mm(50mm2 Al.area)

- LT Lines:• ACSR 7/2.11; 7/2.59/7/3.35• AAC 7/2.21mm(25mm2 Al.area)• ACSR 7/3.10mm(50mm2 Al.area)

Applicable StandardsApplicable Standards Except when they do not comply with

the specific requirements, conductor shall comply with I S 398 Part I-71 amd IS 398 Part II-76 or the latest version thereof

Sizes: Table I. Nominal Al.area 25mm2 & 50mm2 Table II. Nominal Al area 20,30,50,80 &

100 mm2 Table III&IV. Properties of Al and Sterlwises

Freedom from Defects-Wires shall be smooth and fee from all inperfections

Joint in wires & Conductors- All alluminum conductors- No Joints shall be permitted in any

wire Alluminum conductor steel reinforce: Alluminum wires: No two joints shall occur in the al. Wires

closer together than 15 meters Steel wire-No Joints in steel wires used for 20 mm2 to 80 mm2-For 100 mm2 Al.area(614.72 mm+7/13.57 no two joints

shall be less than 15 mm)

Tests: AAAC as per Is 398 Part I, ACSR as per IS 398 Part

II Packing: Gross mass shall not

exceed by more than 10% of the value

AAAC-500 kg ACSR-20mm2 30 mm2 -100 Kg 50 mm2 80 mm2-1500 kg 100mm2-2000kg

Normal Length : AAC-1.0 kmACSR-20,30,50 & 100mm2 2.0 kmLarger lenghts-AcceptableShort length-Nor less than 50% to the max extended 10%

Inspection-At Manufacturers works

2. Outdoor Type 3 phase 11 2. Outdoor Type 3 phase 11 KV/433-250 V Conv. TransformersKV/433-250 V Conv. Transformers

Specification REC-2/1971 (revised 1993) Latest Version

IS-1180(Part I) and IS2026 Ratings-16,25,63 & 100 KVA No load voltage Ration

• 11 KV/433-250 v for 16,25,63 & 100 KVA• 10.45 Kv/433.250 V for 100 KVA only

whrever specified. Taps-No Taps are to be provide

Fittings :a) Two earthing terminalsb) Oil lvel guage Min -50c,30c max 98c) Lifting lugs.d) Breathing device an required by the

purchasere) Drain-cum, sampling valuef) Thermometer. Pocket for 63 & 100 KV fitting

hole Conservator-For 63 & 100KVA-It is obligatorary For 16 & 25 KVA. Manufacturer may adopt their standards

Limits of Temp.Rise- Shall not exceed 450 c (measured by thermometer) in top oil as per IS 2026-Shall not exceed 550c(measured by resistance for winding.

Losses & Impedances-As per IS 2026 Percentage Impedance at 750c shall be 4.5% subject to tolérance

LV Enclosure-Transformer. Shall have a built in 415 V circuit breaker on secondary side ( circuit breaker IS 2516 part 1 &2 Section I 1985-1993)

Tests & Inspection –Routine tests & Type tests shall be conducted as per IS2026

3. Transformer Oil for 3. Transformer Oil for Power/Distribution TransformerPower/Distribution Transformer

Specification-REC specification 39/1985(Revised-1993) IS 335-1983

Scope-i) For new Transformer oil in drums/tankers

ii) For oil after it is filled in the Transformer(The value shall be applicable after 3 days from the date of filling,

Applicable standards- Latest version of IS 335.1983

Important characteristics for new oil and after it is filled in the transformers are stipulated.

TESTS: Shall be carried out in accordance with IS 335-1983

4. 11 KV Porcelain Insulatos and 4. 11 KV Porcelain Insulatos and FittingsFittings

Specification:REC Specification 3/1971 (Revised 1993’Part I: Insulators

Scope-Porcelain Insultors((Pin & Strain Insulators) for use on 11 Kv

Applicable standars-As per IS 731 and IS 3188 as amended from time to time.

Classification and Dimensions: • Both Pin and Strain insulators shall conform to

type B of IS 731• Strain Insulators shall be of ball and socket type

or tongue & Clevis type as required by the purchaser


Failing load-Mech.Failing load-Min 5 KN(pin Insulator)

Electro mech Failing load of min 45 KN (for strain insulator)

Greepage Distance(Min)- • Highest system voltage 12

KV• Normal and moderately

Polluted atmosphere 230 mm• HPA- Pin Insulator

320 mm• Strain Insulator 400mm


Tests-As per IS 731 Marking-Each insulator shall be legibly and

indelibly marked to show the following Name or Trade mark of manufacuturer Month and year of manufactorure Minimum failing load in KN ISI Certifcate mark

Part II Insulator Fittings Scope-i) Pin For 11 KV Insulators Helically formed pin insulators ties Fittings for strain insulators with

conventional dead-end clamp

Applicable Standards-i) Pins-IS2486(Part I & II)ii) Helically formed fittings IS12048-1987iii)Fittings for strain Insulators-IS2486 Dimension-Pins- small steel head head

type165P Part I to IV as perIS2486 Part II) with min failing load of 5KN

Fittings for strain Insulators - Conforming to IS2486 Part II-1989

Tests: As per IS 2486 Part I Inspection-Manufacturers Place

Specification-REC Spec No. 4/1972(Revised 1979) Applicable Standards-i) Insulator IS1445-1977ii) Fittings IS 7935-1975 or latest version thereoffType of Insulator- Pin Insulator and shackle insulatorBasic Insulation level. -Wet one-minute(For Pin& Shackle) Power Frequency

with stand voltage

Power Frequency,

puncture with stand voltage

5. Porcelain Insulators and Insulators 5. Porcelain Insulators and Insulators Fittings for 415/240V Overhead Power Fittings for 415/240V Overhead Power LinesLines

10 KV (RMS)

60 KV(RMS)

Mechanical loads-Min-Failing load. Pin

Insulator 3.5 KN, Shackle Insulator 11.5 KN

Tests- type testes: Acceptance Tests & Routine test

Marking- Name or Trademark of the manufacturer, year of manufacture, ISI Certification if any

Insulator Fittings:• Pins-Stalk length 135 mm, shank length

125 mm, Min failing load 2.0 KN

Tests-Type Tests, Acceptance Tests &

Routine Test Packing-gross weight shall not exceed

50 Kg

Specification REC Specification -7/1974(Revised 1993) Scope-Oil Immersed, Naturally air

cooled(type ON) outdoor, 3 phase 50 c/s 33/11 KV step down transformers of capcities up to and including 5000 KVA

Applicable standards- IS 2026

6. Three phase 33/11 Kv Step down 6. Three phase 33/11 Kv Step down Transformer Transformer

Standard Ratings

• 630 KVA, 1600 KVA and 3150 KVA with off-circuti taps

• 3150 and 5000 KVA With on Load tap changers

Continuous Max rating & Temp Ris- As per IS2026

Taps: Off circuti Taps-=+2.5% -10% insteps of 2.5 % each on HV windings for HV variation

On load taps-+5% to -15% in step of 2.5 % each on HV winding

Imedance values(at 750c)-Percentage

Impedence shall be 5% for 630 KVA 6.25% for 1600 KVA and 3150 KVA,7.15% for 5000KVA

Losses-Losses shall not exceecd by more than 10% value

KVA No Load Losses(KW)

Load Loss(KW)

630 1.45 7.5

1600 3.0 15.0

3150 4.5 23.0

5000 6.5 34.0

No weightage in prices for offers with lower losses

Guarantee- 1 year from the date of

commissioning or 24 months from the date of receipt at site which ever is earlier.

Test and inspection: Type Test, Routine Tests

REC Specification-REC10/1976 Standards-ISS 3070 Pt- I -1985 or the

latest version Voltage-Rated voltage 9 KV (rms) Nominal Discharge Current- 5KA

7. 11 KV Lightning Arrestor7. 11 KV Lightning Arrestor

Guarantee- 12 months from the date of

installation or 18 months from the date of receipt by the purchaser whichever is earlier

Tests: 1) Routine Test 2) Type Tests Inspection-Place of manufacturer

Specification –REC Specification 12/1979 (Revised 1993)

Applicable standards-IS 13118(Circuit Breaker) IS 2705 CTS,

8. 33/11 Kv Vaccumm/SF6 Circuit 8. 33/11 Kv Vaccumm/SF6 Circuit BreakersBreakers

Rated Voltage - 33 KV Rated Normal Current -630 amps Rated Short Circuti Breaking current -

12.5 KA(730MVA) Rated Short Circuit making current-

2.5 times the rms value of the ac component of rated short circut breaker current)

CTS for metering and protection- CTs shall be supplied along with Circuit Breakers

Test: Type test & Routine Test as per IS

9. Porcelain Insulators and Insulators 9. Porcelain Insulators and Insulators Fittings for 33 KV Overhead power linesFittings for 33 KV Overhead power lines

Specification- REC Specification 13/1979 Applicable Standars-Insulators IS 731-

1971 Insulator fittings IS 2486 Part I-1971 and IS 2486 Part II-1974 or the latest version

Insulator: Basic Insulation levels-Highest system

voltage 36 KV(rms),Power frequency with stand test 75 KV(rms),Impulse voltage with stand test 170 KV (peak)

Mechanical Load-Mi. Failing Load, Pin Insulator 10 KN, string Insulator units 45 KN

Creepage distrance min- NPA 580mm HPA 840

mm Tests: Type tests: Acceptance tests; Routine

test Insulator Fittings Pins for Pin Insulator Type and Dimensions-Pins with large steel

head type L300N as per IS 2486 Part II Min. Failing load-10 KN

Tests: As per IS 2486 Part I Type Test; Acceptance Test & RoutineTest

String Insulator Fittings: Test- As per IS 2486 part I Type Test;

acceptance Test & Routine Test Marking & Packing-I) Name or Trade

mark of the manufacturer II) Year of Manufacturer III)Packing not exceeding 50Kg

10. 11 KV Vaccum Circuit Breakers10. 11 KV Vaccum Circuit Breakers

Specification: REC 22/1983 Applicable standars-IS 13118 Circuit Breakers IS 3156 Voltage transformers IS 2705 Current Transformers Rated Voltage-12 Kv Nominal system Voltage-11 Kv Rated Current-Standard rated normal current

400 A, Busbar rating of Indoor type vaccum circuit breaker 800 A

Rated Voltage of operating Device-Standard DC voltage for opeating devices shall be 24 V

Voltage Transformer for Metering-Rated voltage ratio-11 KV/110 v, Rated output(burden)-100 VA per phase Accuracty clas-1.0

CT for Metering & Protection: Transformer Ratio i) 50-25/5A ii) 200-

100/5A iii) 300-150/5A These will be sufficient for SS capacities

up to 2x5 MVA Accuracy class-For Metering 1.0, For

protection 5P Accuracy Limit Factor 10 Test: Circut Breaker-IS 13118-1991 Voltage Transformer-IS3156(Part I) -1992 Current transformer-IS 2705(Part I)-1992

11. 11. Aerial Bunched Cables For LT linesAerial Bunched Cables For LT lines

Specification-REC 32/1984 Rated voltage of the cable-1100 V Applicable Standards

• IS : 10810-1984-Methods of test for cables• IS : 8130-1984-Conductor For Insulated Cables• IS: 6474-1984: Polyethylene Insulation of

cables• IS: 398(Part IV)-1979-Al.Alloy Conductor

General: I) Insulated Phase condcutors(With additional street lighting conductor, if provided) shall be twisted around the aluminum alloy messenger wire, which shall take all the mechanical stress. The messenger wire shall also serve as earth-cum-neutral wire.

Standard Size: Phase 16mm2, 25 mm2, 35mm2 and 50 mm2

Mesenger Wire-25 mm2, 35 mm2

Phase conductors- I) Phase conductors and street lighting conductor shal be insulated with black weather-resistant, polyethylene suitable 100 v insulators

II) These shall be suitalbly compacted II) Tensile strength of the Al.wires used shall not be less

than 90 N per square milli meter Messenger(Neutral Conductor) i) Base Messenger wire

shall be made of All-alloy generallly conforming to IS 398 Part IV-1979

Ii) There shall be no joints in any wire of the stranded messanger conductor except those made in the base rod or wires before final drawing.

Test for Phase/Street Light Conductor IS 8130, 6474 and 10810

Test for Messenger Wire- IS 398 Part IV

Specification-REC 33/1984(Revised 1991) Advantages: The advantage of all alluminium alloy

conductors include lighter weight, longer life due to higher surface hardness, higher resistance to coorrosion particularly in saline atmosphere and reduced possibility of theft of wires.

One of the factors coming in the way of large scale use of AAC is the higher price as compared to ACSR even though the difference has been narrowing down as more manufacturers are taking up production of AAC

12. Alluminium Alloy Stranded 12. Alluminium Alloy Stranded conductors for Overhead Power Linesconductors for Overhead Power Lines

Scope- for use on 33 KV, 11 KV and LT overhead lines Conductor Sizes for Different Application 11 KV and LT linesI) 3/2.50 mm (14 mm2 Alloy area) for street light onlyII) 7/2.00 mm(20 mm2 Alloy area)III) 7/2.50 mm(30 mm2 Alloy area)IV)7/3.15 mm (50 mm2 Alloy Area) 33 KV linesi) 7/3.15 mm(50 mm2 alloy area)ii) 7/3.81 mm(80 mm2 Alloy Area)iii) 7/4.26 mm(100mm2 Alloy Area)Applicable strandards- IS 398 Part IV -1979Table I- Properties Alluminium alloy wire Table II- Properties of Aluminium ConductorTests-To comply as per IS 398 Part IV -79

Packing: Gross mass shall not exceed by more than 10% value

Normal Length-

Conductor size Gross Man( kg)

14 mm2-30 mm2 1100 kg

50 mm2 1500 kg

80 mm2 1600 kg

100 mm2 2000 kg

Conductor size Gross Man( km)

14 mm2-30 mm2 2.0 km

50 mm2 1.7 km

80 mm2 1.3 km

100 mm2 1.1 km

Longer Length –Acceptable Short lengths-Not less than 50% of normal

length to the max. of 10% quantity order Inspection-At the place of manufacturer.

Specification-REC 43/1987 Scope-Suitable for off-load conditions Applicable strandards-IS 9920(pt-I to

IV) Rated Voltage-12 Kv Rated normal current-400 A Rated Lighting impulse with stand

voltage KV(Peak)• To earth and between pole-75 Kv• Across the terminal of open switch-85 KV

13. Specification for 11 Kv AB switches13. Specification for 11 Kv AB switches

Rated one-minute power frequency with stand voltage KV(rms)

i) To earth and between poles 28 KVii) Across the terminals of open switch 32

KV Rated short time current-16 KA Type Test-IS 9920 Routine Test- IS 9920 Inspection-At the place of manufacture

rec specifications

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