Resistance Grounded Systems

[mikelagoda]

Hello,

I have a 4160V resistance grounded system and have to purchase a MEI switchgear (switches only, no breakers). I am planning on providing metering for this switchgear. The questions that i have are:

Can PT's in this switchgear be WYE connected with a solidly grounded neutral? Or do i have to use open delta connection?

I have a concern that WYE connected PT's might cause the fault current to bypass the resistor and that inbalance in the PT loads might cause current flow back through the resistor creating unnecessary alarm.

Thanks,

Mike

 

[jimday]

Mike,

I've not done a lot of this, but the last time I did MV breaker controls it was for a 5kV resistance grounded system. The PTs we used were either delta or open delta primary with a grounded secondary. If you use a wye grounded PT primary you will have introduced a ground in parallel with your HRG. Even if it was not unsafe you would potentially need to set your HRG GF relay higher to accomodate any current imbalance in PT primary. Use delta or open delta PTs...... Go to www.ipc-resistors.com, they have some good tech info on HRG systems and detection

Jim