VFD MV protection

[Eng.Edward.M]

I have a factory motor of 710kW at 6.6Kv. A VFD will be installed, but I already have a SEL 710 relay above. Would you like to know that only the 50/51 functions are enough for VFD protection?

 

[davidbeach]

The 50/51 functions would be the only that make any sense. The relay will no longer be able to tell anything about the motor itself.

I’ll see your silver lining and raise you two black clouds. - Protection Operations

 

[wcaseyharman]

This is probably included under the 50/51 umbrella but depending on how your system is grounded you might still set a 50G or an 51G element to trip for ground faults on the motor circuit conductors to the VFD.

 

[jraef]

The 710 standard variant does not work with VDDs, you need the 710-5 version.


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