UPS's & I.G. Circuit

[Hal Sullivan]

If the UPS is 208 VAC input and output with an Isolated Ground required by the electrical engineer or customer how is this wired? There is no UPS manufacturer, to my knowledge, that provides a five wire static switch so if you have to go to the static bypass or maintenance bypass that you can pass the I.G. ground upstream to the seperately derived source where you should be tying the IG to the XO.

 

[dereckbc]

Well IG doesn't buy you anything if you are using a true dual conversion UPS (AC-DC-AC) as it is a true SDS. However the IG would originate in the PDU of a large scale UPS.

 

[brian john]

The UPS is 208 VAC input with single source input and 208/120 3 phase 4 wire output?

Or is it dual source 208 VAC input with bypass 208/120 VAC and 208/120 output.

Either way a 5 wire static switch makes NO SENSE...trying to TRULY isolate any secondary with all the VOODOO HODOO some engineers doodoo DOES NOT WORK.

Ground is Ground (the metallic structures that serve in place of earth) in a facility and will always be connected some how some way. I have seen structures on isolators and still there were issues.


Want to have a system without any ground issues?

I HAVE THE PERFECT ANSWER, this system is the best way to go. The UPS and critical loads be sure they are connected per the NEC...NO DOWNSTREAM GROUNDS.