Protection Engineering Basics and Schemes Protection Engineering | Page 45

defines the highest value of voltage which PT can bear with some duration. If I have a PT of 145KV / 110 V which have voltage factor of 1.2 for 30 sec, that’ s means it can bears 174KV / 132V up to 30 sec, but will damage if duration increase from 30 sec.

Note We do not need to conduct Withstand Power frequency Test, impulse voltage test, rated insulated voltage test and voltage factor test at time of maintenance. They all are factory Tests( FAT). On client request manufacturer will conduct these tests in Factory Testing facility.

1.2.3 Voltage transformers for extra high voltage

We increases size of PT when Voltages increases, but on certain high voltage it is not remain economical, For high voltages or extra high voltage we use cascaded voltage transformer or capacitive voltage transformer

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