PFC Units

[scotsparky]

Just been given a job to repair a 300KVA Power factor Correction Unit I have never worked on them before but realise there are large capacitors in them so am wary. Anybody got any experiance on testing them and what the the risks are there after full isolation.

Thank you

 

[Guest123]

Hi bud.

Dont suppose you know what make and control system it is do you??

 

[Guest123]

EDIT.

I just found a pic similar to one of the types of units I've worked with.

This is whats called an "Active" power factor correction unit.

You can also get "Passive power factor correction units that deal with harmful harmonics in systems. Do you know what type you have.

 

[Darkwood]

Just been given a job to repair a 300KVA Power factor Correction Unit I have never worked on them before but realise there are large capacitors in them so am wary. Anybody got any experiance on testing them and what the the risks are there after full isolation.

Thank you

Fitted a old one once if you shut the incomming supply down leaving the capacitors on line with the installation it should drain them straight away just be weary if you isolate them first from the installation as they cant dump their charge straight away and their is enough to kill you id check with manufacturers for a safe discharge time before you can be safe.
I've no experience with new ones so not sure if they have discharge arrangements etc but i did have to mark the busbar up about the possible shock risk if outgoings were isolated and mains shut down leaving the busbar floating live off the capacitors
It just comes down to been extra cautious and checking with your voltage testers first.

 

[Guest123]

You could always short them out with your pliers!!!!!!!!

 

[scotsparky]

the unit was made in scotland and i have been in touch with them for a chatand they are digging out the scematics for it. They are giving me a quote to refurb/replace it. The unit is 9 years old and had a working life of 4-5 years so its done well.

I think the job will be quoted for the makers to replace with new as a refurb will take a lot longer and use about as many parts.

I was asking out of quoriosity so i know for later if i do have to work on one.

 

[Andy Smith]

Hi mate not sure on how to test by the ideal is to get unity on your supply ( dont mean to tell you how to suck eggs like) be careful and use right capacitors for the job. lots of power stored in these system my friend. sorry cant help anymore but may be able to get some info if needed.

 

[mikeymoo]

does it say the working voltage and the capacity on the caps.? This will be in farads if there large or micro farads for the smaller type. Then can tell u if there safe to discharge. I use to work on a system that used 400v 2 farad caps (about the size ov a coke can) always use a large resistor to discharge (25watts) normaly 5 ohms per volt.

 

[scotsparky]

cheers lads from the sounds of things it wil be subbed to the manufacturer to do. They know what there doing.