Surge Arrest Test Procedures

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DOC No: VEL/P/QAI/001

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Date : 12-05-2006

VIJAI ELETRICALS LTD

PROJECTS DIVISION

HYDERABAD

INSPECTION MANUAL

ITEM: SURGE ARRESTERS


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Date : 12-05-2006

TYPES OF SURGE ARRESTERS & REFERENCE STANDARDS


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Type of Surge Arresters

1. Distribution Class 5 KA Surge Arresters without pressure relief arrangement

2. Intermediate Class 5KA & 10KA Surge Arresters with pressure relief arrangement ina distribution class housing

3. Station Class

a. Discharge class I - 10 KA Surge Arresters with pressure relief

arrangement

b. Discharge class II - 10 KA Surge Arresters with pressure relief

arrangement

c. Discharge class III - 10 KA Surge Arresters with pressure relief

arrangement

d. Discharge class IV - 20 KA Surge Arresters with pressure relief

arrangement

e. Discharge class V 20 KA Surge Arresters with pressure relief

arrangement

Reference Standards:

1. IS:3070(part-3)-1985,

2. IEC 60099-4(Part-4)(second edition)

3. IS: 5621-1980

4. IS: 2071 (Part- I ) 19935. IS: 2071 (Part- II ) 1974

6. IS: 2071 (Part- III ) 19767. IS : 6209 -1982


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I) List of Type tests required for Distribution class Surge Arresters (5KA)Ref Stds: IS:3070(part-3)-1985,IEC60099-4(Part-4)(second edition)

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1. Insulation Withstand tests

a) Lightning Impulse Voltage Withstand test

b) Power Frequency Voltage Withstand test

2. Residual Voltage Test

a) Steep current impulse residual voltage test

b) Lightning impulse residual voltage test

3. Long duration current impulse withstand test

4. Operating duty test ( High current impulse operating duty test )

5. Power frequency voltage versus time curve

6. Arrester Disconnector (When fitted)

7. Artificial Pollution test

II) List of Type tests required for Station class Surge Arresters (10KA & 20KA)

1. Insulation Withstand tests

a) .Lightning Impulse Voltage Withstand test

b) Power Frequency Voltage Withstand test

2. Residual Voltage Test

a) Steep current impulse residual voltage test

b) Lightning impulse residual voltage test

c.) Switching Impulse residual voltage test

3. Long duration current impulse withstand test

4. Operating duty test ( High current impulse operating duty test )

5. Power frequency voltage versus time curve

6. Pressure relief test

7. Artificial Pollution test


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III. Routine Tests

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a) Measurement of Reference voltage test

b) Residual voltage test

c) Partial discharges test

d) Sealed leakage test

IV. Standard Acceptance Test

a) Power Frequency reference voltage test

b) Partial discharge test

c) Residual Voltage test

d) Leakage Current test

e) Seal leakage test (Special test)

f) Galvanizing tests

g) Special Thermal Stability test


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Surge Arrester Acceptance Test Procedures

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Ref Stards:IS:3070(part-3)1993 & IEC 60099-4

Sampling Plan: Cube root of the quantity offered

1. POWER FREQUENCY REFERENCE VOLTAGE TEST:

This test is carried on 9KV rated Arresters at resistive current crest value of 1mA by using

a 300KV Power Frequency testing transformer. The measurements are made by using

storage Oscilloscope.

SL.No. of

Arrester

Crest Value of

Resistive Current

(Ref. Current)

Reference Voltage

K.V.(RMS)

250 1mA 11.00KV

350 1mA 11.00KV

450 1mA 11.00KV

Result: The Reference Voltage of the Arresters is greater than the rated Voltage (i.e.

9KV RMS). Thus the Arresters have passed the test

2. LIGHTNING IMPULSE RESIDUAL VOLTAGE TEST ON 9KV ARRESTERS:

With the 9KV rated Arresters in circuit the impulse voltage generator is adjusted to deliver a current of

10KA 8 x 20 micro second front time. The residual discharge voltages of 9KV Arrester units are

measured at this current level. The measurement are made by using Oscilloscope.

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The RDV of 9KV Arrester at 5KA are tabulated below :

Sl.No. of

Arrester

Residual Discharge Voltage in KV(Peak)

250 28.08 KV

350 27.04 KV

450 27.04 KV

500 27.04 KV

560 27.04 KV

RESULTS: The Maximum Residual Discharge Voltages are well below the guaranteedValue (i.e. 32KV (Peak) at 5KA), thus the arresters have passed the test.


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3. PARTIAL DISCHARGE TEST :

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This test is conducted on samples of 9KV rated Arresters as per IEC Publication-270

(Method of measurement of P.D. of high voltage apparatus) for satisfactory absence from

partial discharges.

The Power Frequency Voltage is applied to the Arrester Units from 300KV transformer

The voltage is increased up to rated voltage of 9KV and then decreased to 1.05 times

MCOV i.e.., 8.0KV (RMS). At this voltage Partial Discharge is measured by means of P.D

meter conforming to IEC Publication 270.

The results are tabulated below:

Sl.No. of

Arrester

Voltage applied

KV (RMS)

P.D. Level

Pc

250 8.0KV 5 Pc

350 8.0KV 5 Pc

450 8.0KV 6 Pc

Result: The Internal Partial Discharge is well below 10 pC which is the maximum as per

the specification and thus the Arresters have passed the test.

NOTE: In the above test procedure 9KV rating is taken as a sample


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4. LEAKAGE CURRENT OF THE SURGE ARRESTER :

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The leakage current is measured by using storage Oscilloscope at MCOV of the surge

arrester.

Compliance: It should be less than 300 micro amps or as indicated in the approved GTP.

5. a. SEAL LEAKAGE TEST: ( This test is performed by any sensitive methodadopted by the manufacturer)

Vacuum over Water (Dip Test) Method for distribution & Intermediate class Arresters.

The Surge Arresters are completely immersed in water bath and subjected to a partial

pressure of -350mm of Hg for not less than 2 minutes to check the air leakage from the

arrester. Continuous bubbling from the arrester is an indication of seal leakage

Subsequently the arresters are cleaned and tested for IR value by 5KV megger and the

criteria for passing is that the IR value should not be less than 1G Ohm.


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b. SEAL LEAKAGE TEST: ( This test is performed by any sensitive

method adopted by the manufacturer)

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Water (Dip Test) Method for station class surge arresters.

The Surge Arresters are completely immersed in water bath .After a period of 30 minutes

the surge arresters are lifted out & dried. Subsequently the arresters are cleaned and tested

for IR value by 5KV megger and the criteria for passing are that the IR value is as follows:

Arrester rating IR value in G ohms

9KV 10KA 1G ohm (min)

12KV 10KA to 18KV 10KA 2G ohm (min)

30KV 10KA to 42KV 10KA 5G ohm (min)

60 KV 10 KA & above 8G ohms (min)


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6.GALVANIZING TESTS :

a) Test for Uniformity of Coating

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Samples are selected at random . A solution of 360 grams of CuSO4 in on liter of distilled

water is prepared. The specific gravity of the test solution is adjusted to 1.18.

The sample is subjected to four dips in the prepared standard solution, each dip lasting for

one minute. After each dip the samples are cleaned with water and then dried .

Result :

After the last dip no copper deposition could be detected on test sample. The sample has

passed the uniformity of coating test satisfactorily as per IS : 3070 (Part-III) of 1993 & IS:

2633-1986

b) Test for Mass of Zinc Coating by Stripping Method:

The Stripping solution is prepared as follows:

Dissolve 20 g of antimony trioxide (Sb2 O3) or 32 g of antimony trichloride (SbCl2) in 1000

ml of concentrated hydrochloric acid.

Immediately before test, prepare the stripping solution by adding 5ml of the solution

prepared under above to 100ml of concentrated hydrochloric acid. Mix well.

Prepare the test samples (preferable 20mm x 20mm or 40mm x 40 mm), the samples

should be dry & clean . Take the weighment in mg, record the weight (M 1) . Then immerse

the test piece in the stripping solution . When the evolution of hydrogen ceases or a few

bubbles are being evolved, the test pieces shallbe taken out, washed in water, wiped off

well with clean soft cotton clothe , fully dried and weighed (M 2) again. Calculate the massof zinc coating/unit area as below.

Calculation :

M = M1 M2 x 106

A

WhereM = Mass of zinc coating in g/m2 of surface

M1 = Original mass in g of the test piece,

M2 = Mass in g of the stripped test piece, and

A = Coated area of the original test piece in mm


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7. SPECIAL THERMAL STABLITY TEST

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This test is done on three samples of ZNo Blocks / sections selected randomly from the

current routine production and having the same dimensions and characteristics as those of

the arresters under test.

Adjust the generator charging voltage as per Table 4 of IS: 3070(Part-3)1993/Table 5 of

IEC60099-4 (part-4) second editions for line discharge test

Pre heat the block to 70 oC +/- 3 oC and then apply High current impulse (75Amps for1000 microseconds for distribution class /)* , as short as possible (not longer then 100 milli

seconds) apply rated voltage of the block of 3KV for 10 sec and then immediately apply

MCOV (2.55 KV Rms) and monitor the leakage current for 30 minutes.

Compliance: The leakage current of the ZNo block should be thermally stable

* In case of station class surge arresters (Class-2,3,4,5) two long duration current impulses

as per Table 5 of IEC60099-4 (part-4) second edition for line discharge test with an interva

of 60 seconds between shots is applied

References : 1. As per Figure 3 of IS : 3070 (part 3) of 19932. As per Figure 4 of IEC 60099-4 part 4

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Surge Arrest Test Procedures