High Resistance Grounding Units
High Resistance Grounding Units
(OP)
Just seeking advice of the higher powers on this board. I have a client who has three ungrounded secondary unit substations. They want to connect high resistance grounding units to these substations. I understand the concept of these HRG units but I am not sure of how to physically wire them. Do you need a secondary feeder breaker to feed these units or can you tap directly off the transformer neutral?
I believe the units are Eaton C-HRG.
The Contractor is asking that we provide a secondary feeder breaker when wiring these HRG's. From my reading I thought you only need a direct connection from transformer neutral to the HRG, hence not needing this secondary breaker.
Any information you guys have, as always, is appreciated.
Thanks
I believe the units are Eaton C-HRG.
The Contractor is asking that we provide a secondary feeder breaker when wiring these HRG's. From my reading I thought you only need a direct connection from transformer neutral to the HRG, hence not needing this secondary breaker.
Any information you guys have, as always, is appreciated.
Thanks





RE: High Resistance Grounding Units
For a wye transformer, you just need a HRG unit with a resistor and associated fault sensing equipment and it is connected to the transformer neutral (and ground, of course). There is no circuit breaker in the neutral.
For a delta winding, you will need some type of grounding transformer, either a delta-wye or zig-zag unit plus the grounding resistor. This can all be provided in one package or the grounding transformer can be a separate item.
RE: High Resistance Grounding Units
I should have mentioned they were ungrounded wye transformers. Thanks for the info
RE: High Resistance Grounding Units
If this is just a disconnect without alarms to indicate an open breaker I would strongly resist the installation of a breaker. In Canada an automatic breaker in a grounding conductor is prohibited by Rule 10-800 of the CEC.
respectfully