Transformer Testing - Tan Delta / Capacitance Test 1

[RRaghunath]

It is said that the test should be conducted by applying high voltage and if not the result may not be dependable. The transformer is of 125MVA, 132 / 33kV rating and new. Please advise me whether it is OK to conduct the test at 500V. The testing is part of commissioning tests.

Thanks.

 

[HiSet]

HV Tan delta testing at 10kV is pretty much standard followed by many utilities worldwide.

 

[gvakre]

The reason behind testing the tan delta at rated voltage or high voltage is the result can get effected due to partial discharge(if any)and will be actual value at rated voltage.But I agree that 11kv test is ok provided the trf does not have pds beyond limits.

 

[hy]

It`s all Ok what has been said for this voltage and power range transformer.

- mayor of utilities use tangente delta and capacitance tests of 2.5 or 10kV that is enough hign so as to detect problems in commissioning transformers.

- at rated and upper voltages is used for lab tests only for the cost and facilities.

lower tensions are more for measuring capacitance only (schering bridges).

- also you can perform excitation current tests with this test devices.

hy

 

[scottf]

gvakre-

Most factories do cap. and df (dissipation factor or tan delta)measurments at 10 kV and rated voltage to look for difference in values between the 2 measurements. Partial discharge will not affect the capc. or df measurement. PD must be measured seperately with a PD bridge and is normally done in conjunction with the hi-pot or power-frequency withstand voltage test.

 

[jbartos]

Suggestion: Visit

http://www.tneb.org/rd.htm

http://www.amroh-electronics.de/avo_data/BiddleMAmp/HVtest/Actsphnx.pdf

(see instruction which may come with test set)

http://www.itee.uq.edu.au/~aupec/aupec99/vashishtha99.pdf

(test methods evaluation)
etc. for more info