corner grounded delta
corner grounded delta
(OP)
We have a deep well pump application were a 480V soft-start feeds a step up 480-2400 delta delta transformer, which in turn supplies a 200hp pump.
Should the 2400V delta secondary be corner grounded or ungrounded?
(the 2400V conductors are run underground, in concrete encased conduit, and then down into the well)
Thanks
Should the 2400V delta secondary be corner grounded or ungrounded?
(the 2400V conductors are run underground, in concrete encased conduit, and then down into the well)
Thanks






RE: corner grounded delta
The 2400V circuit should be high-resistance grounded with about 1 ampere of resistive fault current. It is unfortunate that a wye 2400V winding was not specified—that would have allowed for a simplified application of a resistor from H0-to-ground for this purpose. This scheme will limit damage under fault conditions, but damp any transient or resonant overvoltage on the 2400V circuit. Simple non-tripping ground detection could be accomplished by monitoring current through or voltage across the grounding resistor.
Because of the simplicity of the arrangement, surge protection at 2400V is probably unnecessary.