Download Power Grid Corporation of India 400 220 Kv Vocational Training Report PDF

TitlePower Grid Corporation of India 400 220 Kv Vocational Training Report
File Size1.7 MB
Total Pages25
Document Text Contents
Page 12


The potential transformer are basically step-down transformers. The connections of

voltmeter when used in conjuction with the potential transformer for measurement of

high A.C. voltages. The voltage to be measured is applied across the primary winding

which has a large no. of turns is coupled magnetically to the primary winding. Turn

ratio is so adjusted that the secondary voltage is 110V when full rated primary voltage

is applied to primary.

Potential transformers are used to operate voltmeter, the potential coils of

wattmeter and relays from high voltage lines. The design of potential transformer is

quite similar to that of power transformer. But the loading capacity of a potential

transformer is very small in comparison to that of power transformer. The loading of a

potential transformer some time is only a few volt amperes. These transformers are

made shell type because this condition develops a high degree of accuracy. For

medium voltages i.e. upto 6.6 KV the potential transformer are usually of dry type,

between 6.6 KV to 1.1 KV they may be either dry or oil immersed but for voltage

more than 11 KV they always oil immersed type. An out of door type oil immersed

voltage transformer having ratio 66000/110.


400 KV CVT

A capacitor voltage transformer (CVT) is a transformer used in power systems to step

down extra high voltage signals and provide a low voltage signal, for measurement or

to operate a protective relay. In its most basic form the device consists of three parts:

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