Backup Power

[jimbo123]

I have a 120 / 208 panel fed by a 45 kva trans that supplys power to plc's , meters and other low voltage equipment by about six cb's from this panel . Should this trans short out all their process would come to a halt until power is restored and time would be a critical factor.

Is there a quick method to resupply power to the panel ? Would a second trans wired to a double throw switch to be able to switch each load side of trans to the panel be code complient ? Each trans will have its own primary cb.

Any other ideas ?

Other circuits are also in this panel but are not critical. There is no other source of 120volts within atleast 300'.

 

[iwire]

Sure, add in a hardwired UPS between the trans and the panel.

 

[Steve O]

If uninteruptable is the critical time factor then the UPS is the way to go if time is needed to shut down the processes.

If 8 or 10 seconds isn't critical then an ATS with a second transformer.

If they are considered critical loads and will take down production and loss revenue for the day then both would be a good idea.

 

[kingpb]

Convert the PLC power and meter power to DC, and then use a small inverter off the same DC system batteries to get the little AC needed. If possible switch all the critical load to DC. But, remember putting in a UPS also adds a point of failure, so are you any better off then using the single transformer? I'd day that transformer probably is going to be more reliable than a DC or UPS system. Those things are maintenance intensive.

How often does the source to the transformer go down? Do you have redundant feeds to the main service? You can start to formulate a whole bunch of questions when you open the critical load can of worms.