UPS supply problem

[Perci]

Hi

Recently we were asked to put in an 80A 3 phase supply to a UPS system, we carried out the work to the manufacturers guidelines with an 80A mccb in the panel board. To much annoyance of all the office workers, when the supply was turned on it blew all 3 of the main fuses that are rated at 100A.

Has anyone had any similar problems?

 

[freddo]

Single phase links left in?!!

What other loads are connected? An additional 80 amp load connected might be too much for the 100A supply, but I wouldn't expect the fuses to blow instantly, unless the supply was already overloaded.

 

[Perci]

Do you mean inside the the actual ups box? We didn't install that part so that could be! Wouldn't you expect the 80A mccb to trip first with that kind of fault conditions?

That was my first go to that they were overloading their supply but with load tests they are pulling 40A per phase so it's not too bad

 

[freddo]

Possibly, I edited my first reply.

 

[Pete999]

Single phase links left in, not an Emerson AP 400 UPs is it?

 

[Perci]

I'm not intierly sure to be honest when I get back to the office tomorrow I'll find out. There is 10 seperate ups backups but we were just given a 5c 10mm flex that needed a supply.

 

[Pete999]

If there are 10 separate modules in the UPs it more than likely not an AP Emerson type as they usually come in 7.5 10, 15 KW etc

 

[Perci]

Yea I'm not to sure on the specs of the ups I just no it's quite a large set up. It's is used to keep the mainframe computer racks going during power failure such as what happened when we turned it on

 

[freddo]

Nice avi BTW, I don't think I've ever seen that many sockets installed in a length of dildo trunking!

 

[Perci]

That is at the same place as this ups. It's one of the most rediculous things 20 twin sockets per length and there is 3 of them in the same room!

 

[UKMeterman]

dildo trunking!

What kind of company were you fitting them for, and did they have a lot of ladies needing powered entertainment?

 

[Pete999]

What kind of company were you fitting them for, and did they have a lot of ladies needing powered entertainment?

Missed that dildo trunking, what a laugh

 

[freddo]

Missed that dildo trunking, what a laugh

I thought I'd just slip that in there.

 

[westward10]

I thought I'd just slip that in there.

Ouch

 

[dmxtothemax]

Hi

Recently we were asked to put in an 80A 3 phase supply to a UPS system, we carried out the work to the manufacturers guidelines with an 80A mccb in the panel board. To much annoyance of all the office workers, when the supply was turned on it blew all 3 of the main fuses that are rated at 100A.

Has anyone had any similar problems?

as the load will be highly inductive, then the load will be very re-active.
Sort of like a start up surge on an electric motor.
You might need to use breakers with a time lagg
such breakers are used on electric motors and
are designed to cope with a large but short start surge.
the term used in Australia is "slow-blow'.

 

[Perci]

In case anyone ends up on this thread it turned out to be a faulty MCCB. Of all things!

 

[Marvo]

Thanks for letting us know.