gawk

Hi people,

I am a (mainly) domestic sparky, part p etc. Just been to look at a factory, that I'm doing some work on, (connecting new machines, new lights etc,) the company are moving in soon.
The switchgear is pretty old but seems to be in good order, and looks to have been installled well (first impression).
I have come across a switchfuse, (not that old) 100a 3ph, that feeds a metal clad enclosure that houses capacitors. This is not something i'm familiar with. The 3ph switchgear enclosure and fuses are VERY warm, Is that normal? the factory has been empty a while so no load being used. Also, is there any maintainace issues I should be aware of? I dont know when it was installed, but it doesnt look more than 10 years old, but only guessing. I assume it is a power fator correction, but thats as far as my knowledge goes.
Thanks
Gary

CJE

Did you put a clamp on it to see what is actually drawing? Gotta be something there somewhere to produce heat.

wildleg

not really. the capacitor works on charge/discharge, so every ac cycle it is working, unless there are automatic or intelligent controls to take them in and out of line.

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gawk

There is no sign of any electronic controls.

jontar

It's probably for power factor correction, we have a service on the site that doesn't have a "proper" cap bank, where contactors pull in addtional unit depending on load (draw).

It's do to be replaced after our substation A upgrade, but it is currently a cabinet with a whole bunch of caps in it, so if I where to guess 25yrs the electrical engineer figured out at a certain load this will produce a .90 or better power factor.

The only problem with this setup is if we have some of our other 6 big (2500-1500kva) transformers off or barely any load on them, we can actually start to lead to power factor. Fortis (utility)doesn't like this for very long and usaully tour on out from the local shop, I think it interfers with there substation which is 138kv to 25kv, they recently installed a 25kv reactor where they hand the 25kv off to us. I can;t remember if this was because on starting the big plant or several of the smaller plants from a cold start, we were browning out their system or if it was because a few years ago, we took one of the plants down for several months and for time to time would start to lead there power factor.

jontar

I'll see (we are still experiencing some upgrader pains, from the last upgrader/shutdown, so we are really busy lately) if I can get a picture of the old cap cabinet, and the 25kv reactor when I go back to work on wednesday.

Zog

The caps are likely PF correction but could also be for tripping breakers. Should not be warm with little load, sounds like there may be issues.

If you post some photos of the switchgear I can make maintenence recommendations but chances are you will need to sub out the maintenance and testing to a testing company.

gawk

Here are some pics. This is the first time i've looked at them on my computer & notice the yellow & blue phase look burnt ? Maybe loose connections ?


http://instagr.am/p/NJwnfVDFCq/
http://instagr.am/p/NJwk9zDFCp/
http://instagr.am/p/NJw6E3DFC8/

Toronto Sparky

Correcting the power factor for the neighborhood?

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