Applying HRG scheme on small Genset

[nogienugz]

Hi,

Anyone here have applied a HRG (high resistance grounding) scheme on a 60kW EDG? Our process engineers are saying that the system that the EDG is supplying should be ON at all time as much as possible but I feel that putting one on that small load is not worth spending a NEMA 3R resistor bank + SE-330 relay + signal wiring , etc. If the load is several hundreds of kVA then I'd most probably be comfortable. Has anyone done this or may came up with a different approach to keep the EDG on even when there is a Ground Fault?

Thanks,

 

[waross]

If the system is that critical they should be using Uninterruptible Power Supplies.
If you list the issues that will compromise the operation of a diesel generator I suspect that ground faults may be far down the list.
Once HRG was used to provide service with a ground on one phase.
Now NRG is used to limit fault current.
There is not that much fault current from a 60 KVA set.


Bill
--------------------
"Why not the best?"
Jimmy Carter

 

[dpc]

If there are line-to-neutral loads, you must solidly ground. Even if not, high-resistance ground on a 60kW would be uncommon. I've never seen it on a machine that small.

 

[nogienugz]

Same here, I've never seen one applied on a 60kW, 600V EDG and we don't have a L-N loads. And, Waross, you just brought up a good point there. Reliability doesn't only mean 'working even if there is a GF'. Reliability also applies to other discipline, NON-electrical discipline. I've put in an NGR for now in my design like I did with the other areas (but those have 500kW, 600V gensets). Let me see how this goes.