why transformer is conneted to dc for polarity test.it
doesnt work in dc?

Answer Posted / shyam

polarity can be checked with ac also. but it needs phase
angle measurement. with a dc we can observe +ve/-ve
deflection on galvanometer(u can use ma dc analog meter,
dont use digital meter which will have more response time).
apply dc at low voltage for msec time(flick only) otherwise
ct may saturate. please read CPC100 manual of omicron for
further knowledge.

Is This Answer Correct ?    5 Yes 0 No



Post New Answer       View All Answers


Please Help Members By Posting Answers For Below Questions

Whether amorphous core transformer is available in India?.If available then up to what rating of voltage and KVA?.

1304


A powerplant has 8 gensets operating in grid parallel mode. In one genset sometimes there is pf variation and kvar variation. The plant operates in pf mode. When this variation is observed the load is stable, voltage is also stable, freq and genset speed is also stable. How will you check the functioning of pf card. What shall be the ideal output vdc of the pfc, from there it is input to AVR?

1737


we are having 110 Kv,250mA Electrostatic precipitators for coal fired boilers. what will be static voltage and current after discharge and what time it will remain before earthing?

1475


What is VCB? where it is installed at SP. What is SP?

1743


Is there possible to Test Transformer for Overfluxing Capability. Or is there any firm who does Overfluxing Test on Transformer?

2644






why impudance relay used for medium transmission power system? why not others?

926


Define transfer function?

749


how to avoid electrical shock how capacitor store charges wat are the speed control of induction motors state faradays law flemings left hand rule what is rotary converter wat is transmission and distribution what are the sources of energy abrevation of acb,vcb,sf6,igbt what is output equation of transformer which test copper iron and iron loss are calculated what is eddy current draw a single line diagram (10 marks) draw direct online starter(10 marks)

1447


how will reduce the voltage. if 12volt/250ma transformer toreduce 6 volt

1529


WHAT IS ELECTRICAL MAINTAINTENCE ?

1564


where is core-type and shell-type construction suitable for transformers ?

1651


what is the safty of poly phase tranformer?

1643


Why the dc voltage drop during starting of emergency lube oil pump? The Voltage drop from 135kv to 125 kv for one min. before re-establish to 135kv?

1796


what is mind in cable

1576


why the starting voltage drop in a cable needs to be limited?what is percentage of the voltage drop allowed during starting?

1365