(METALLISED POLYPROPYLENE)
|
TESTING PLAN |
||
|
Testing plan is divided into three types of tests. |
||
|
|
Routine tests |
|
|
To be carried out by the manufacturer on all the units, for which a routine test certificate will be supplied. |
||
|
|
Acceptance tests |
|
|
To be carried out on capacitors, the number of which is to be decided between the customer and the manufacturer mutually. |
||
|
|
Type tests |
|
|
Normally a certificate for the type test will be provided. However we can offer type tests on single unit at extra costs and with previous arrangement. |
||
|
Routine Tests |
||||||
|
A |
Visual examination |
|||||
|
B |
Sealing test at 800C + 50C for 3 Hours. |
|||||
|
C |
Test for output and capacitance. Current will be measured at rated voltage and KVAR will be calculated from the same. OR Capacitance will be measured directly across a Schering bridge and KVAR will be calculated from same. Unbalance between phases will not exceed 5%. |
|||||
|
D |
Insulation resistance test. Insulation resistance will be measured on a microampere ammeter across a 500 volts stabilised, ripple-free D.C. supply between all the terminals together and container and the value so measured will not be less than 50 MW . Note : 1) When one terminal is body itself, this test does not apply. 2) Readings with hand Megger are not reliable. |
|||||
|
E |
Voltage test between terminals. AC voltage (Vt) =1.75 times the rated voltage(Vo) will be applied for 2 seconds between terminals. The capacitor will withstand this test Note : On subsequent repeated testing, test voltage applied will be equal to 80% of the above value. |
|||||
|
F |
Voltage test between terminals and container. An A.C. voltage of 2.5 KV, 50 Hz will be applied between all the terminals together and body for the period of 2 seconds. The capacitor will withstand this test. Note: 1) When one terminal of capacitor is connected to body, this test does not apply. 2) For Type test, the duration will be 1 minute & for routine test the duration will be 2 seconds. |
|||||
|
G |
Voltage test between terminals and container for capacitor banks This test will be similar to the (F) above except that all the fitting like voltmeter, instrument transformer or any other phase to earth apparatus may be disconnected during this test. |
|||||
|
H |
Test for efficacy of discharge device A D.C. Voltage equal to 1.41 times the r.m.s. rated voltage of capacitor will be applied along with its discharge resistance. The voltage will be switched off and time will be measured to reduce this voltage upto 50 volts. This time will be less than 1 minute. |
|||||
|
I |
Measurement of tangent of dielectric loss angle ( Tan delta) This will be measured across the Schering bridge at rated voltage. and the value, exclusive of discharge resistance. It will be less than 0.0025 or 2.5 watts/KVAR. Output test will be repeated at the end of above series of tests. |
|||||
|
Acceptance tests |
||
|
All the routine tests are offered as acceptance tests. |
||
|
Type tests |
||
|
Following type test are identical to similar tests under routine test |
||
|
A |
Test for output and capacitance. |
|
|
B |
Voltage test between terminals and container (for capacitor unit) |
|
|
C |
Voltage test between terminal and container (for capacitor bank) |
|
|
D |
Voltage test between terminals |
|
|
E |
Measurement of tan delta. |
|
|
F |
Thermal stability test This test is to be carried out at 1.2 times rated voltage for 48 hours and the temperature rise at the top of the container is to be measured at two hourly intervals over the last 10 hours. The test is to be carried out as per details in IS-2834. |
|
|
G |
Tangent of dielectric loss angle at elevated temperature. Tan delta during the thermal Stability test at the voltage of the thermal Stability test will not exceed 0.0022 for capacitors with internal inductances. |
|
|
H |
Self-healing test: Voltage of 1.5 X-rated voltage is applied for 10 seconds. There should be five or more discharges. The voltage is reduced to 1.24 X-rated voltage and held for 10 seconds. There should be no breakdowns. C and tan delta are then measured. These should not vary by more than 2% and 0.0001. |
|
|
I |
Short circuit test: The capacitor is charged to a DC voltage of twice the rated AC voltage. It is then directly shorted. Five such shots are carried out within a period of 10 minutes. C and tan delta are then measured. These will not vary by more than 2% or 0.0001. |
|
|
J |
Ageing and destruction tests have been carried out at ERDA, Vadodara. Test certificates for these are available. |
|
|
|
|
