Selection of CTs

[vennivivi]

Hi,

I need to size my current transformers to protect a 1 MW 6,6 k V wound motor. The protection current transformers available in an existing panel are rated 300/1 5P10 10 VA( 0.5 class of accuracy ).I reckon that the starting current for a wound motor is 2-2.5 the full load current that is for my application 200 to 250 amps. Therefore the CTs will not saturate under starting condition.I dont have any data relating to the operating points of the CTs at maximum threshold.Are the CTs suitable for the protection of a motor of this size ?
Thanks for comments.

Grundy

 

[ScottyUK]

What is your relay burden and how long & what size are the pilot wires? You can't just use the CT class in isolation to determine whether your installation is suitable.


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Sometimes I only open my mouth to swap feet...

 

[vennivivi]

Thanks for your reply ScottyUK.The panel is already equipped with an existing protection relay which was used previously as a transformer feeder.The protection relay,SEPAM 2000, is also suitable to protect a motor feeder.

Grundy