Electronics > Beginners
Earth leakage fault - consider using an whole lab insolation traffo - discuss
(1/3) > >>
MadScientist:
Hi, IN my home lab/office I have the usual test gear , small CNC mills etc

Annoying my house which i bought three years ago , occasionally tripos its RCBO for no apparent reason , typically flicking the RCBO on again ,restores the status quo

Tracking down the issue is exceeding difficult , the RCBO protects essentially two mains rings and is not on the lighting circuits ( The house was built in 1995 and is coded correctly for the time  ).  This year in 12 months I have three-four trips

I will replace the RCBO soon  and Im considering putting a separate one on each main ring to start the process of segregating the problem

In the mean time I have two choices , Isolate  the whole lab on a 230-230 isolating traffo, ( to eliminate leakage currents from the lab  ) or putting the computing resources on a UPS ( which is what I am doing first ) The UPS isnt really a solution long term , the long term solution is no trips !

The isolation traffo isnt a long term idea, but would at least eliminate over 12 months is anything in the lab generating earth leakage currents, but I have had the RBCO trips when nothing was powered on in the lab . I am aware of the common mode issues with isolation , but putting the whole lab on one would generally eliminate issues of inadvertent grounding

After that Im not sure how to track down this elusive fault , due to the infrequency of its occurrence

ideas ?


Thanks

Dave
vk6zgo:
Some heavy domestic appliances have a bit too much leakage by design to be used on an RCBO, & in Australia are allowed to be driven from an unprotected source.
Maybe they aren't in your country-----where are you?

In this country, things like refrigerators, washing machines & dryers are all used from switched power sockets, & are used RCD/RCBO protected.

Hot water systems, stoves, etc are hardwired, & some of those may be in the group which will be marginal with an RCD/RCBO.

The problem could be a faulty RCBO though---- such things do fail, eventually, just as conventional circuit breakers do.
madires:
An isolation transformer for the whole lab is a bad idea because you wouldn't notice a bad device besides other issues. I'd install a dedicated RCD (plus mains) for the lab, one (plus mains) for the data center, and also one for each mains ring (UK?). This way you would have only a partial blackout if one of the RCDs is triggered.
MadScientist:
My next step is to consider putting the lab on a seperate RCBO , its not " too " awkward as , my lab is close enough to the main distribution board , but as always trying to run twin +earth wires through an existing decorated house is a PITA.

Im in ireland , and the practice here is as per the UK.  Heavy loads like Cookers etc are not on a RCBO , ( in 1995) , newer houses now have all house RCBOs however

Ill replace the RCBO as a first step , thats the easiest and a have a 500W UPS coming to at least protect the computers

its a bugger of a problem to track down
MadScientist:

--- Quote ---because you wouldn't notice a bad device besides other issues
--- End quote ---

There is nothing to stop me fitting a local RCBO to my safety transformer , which would detect local  leakages to the PE wire on equipment connected
Navigation
Message Index
Next page
There was an error while thanking
Thanking...

Go to full version
Powered by SMFPacks Advanced Attachments Uploader Mod