Anyone run one of these QO generator panels?

F

fastline

Senior Member
Location
midwest usa
Occupation
Engineer
chrome-extension://efaidnbmnnnibpcajpcglclefindmkaj/https://download.schneider-electric.com/files?p_enDocType=Instruction+sheet&p_File_Name=PHA52731.pdf&p_Doc_Ref=PHA52731

I stumbled into this and have to admit I haven't been into one quite like this. What I am trying to visualize is any use of the plug-on neutral bars that get disconnected with the transfer switching. It appears you could configure some load shedding with this setup.
 
Looks like a nice transfer switch that switches the neutral. They provide instructions for how to wire with bonded or unbonded generators. I don't see how plug on neutral changes anything. It looks like the neutral bus is just connected to utility or generator depending on the transfer breakers (appears to use a 3 pole mechanism). Load shedding would be manual by turning breakers on or off since its a manual transfer switch. Neutral connection wouldn't be any different whether old school type or new PON.
 
suemarkp said:
Looks like a nice transfer switch that switches the neutral. They provide instructions for how to wire with bonded or unbonded generators. I don't see how plug on neutral changes anything. It looks like the neutral bus is just connected to utility or generator depending on the transfer breakers (appears to use a 3 pole mechanism). Load shedding would be manual by turning breakers on or off since its a manual transfer switch. Neutral connection wouldn't be any different whether old school type or new PON.
Click to expand...
Unless I am seeing it wrong, the PONs are discrete circuits that will be lifted during the transfer. I guess maybe someone could clarify that for me. For instance, when running on generator, neutrals on the right PON are bonded to the utility neutral, but no connection to generator neutral?
 
I just looked at the diagram in the install manual and not any pictures of the bussing. It appeared there were two neutral bars tied together and they both get switched when flipping from utility to gen. There is probably something tying the left and right bars together.
 
suemarkp said:
I just looked at the diagram in the install manual and not any pictures of the bussing. It appeared there were two neutral bars tied together and they both get switched when flipping from utility to gen. There is probably something tying the left and right bars together.
Click to expand...
If you're talking about the bar towards the bottom, that is L2. However, like you, I suspect there is something tying things together and I sort of suspect an error in the diagram that is jacking with me because the entire point of a 3 pole transfer is to isolate the neutral.

I now have to see if I can find a pic of the bussing just to clear my head...lol I sort of think the breaker switching is actually on the outside of the bonds shown in the diagram, so the center neutral bar at top stays bonded to the PONs all the time, which would make sense.
 
It must be the case that all the neutral bars (PON and normal) are tied together and tied to one of the three poles of each of the two interlocked three pole breakers. The other poles of those breakers are tied to the two ungrounded busbars as usual.

Cheers, Wayne
 
When I do one of these with a generator inlet using a regular panel I typically use a 100A breaker on the utility size and a 50A breaker on the generator side, to match the 50A generator inlet.
Looks like the mains are standard QO 3 phase breakers, I wonder what the rating of the busbar is? and if you could replace the utility one with a larger one? :unsure:
 
You must log in or register to reply here.
Top