Rcd tripping

[Rp74]

Hi
I have a workshop with 3 phase electrics. The feed comes into an 30ma rcd then into the main board where it supplies my lights/sockets and 3 phase machines. Everything works fine except a new 240v 16a machine. Its plugged into a 16a socket but every time I press the start button it trips the rcd (but not the main board). I'm struggling to find someone to have a look for me so trying to get an idea as to what the problem may be. Any idea as to where to start? NOTE I will obviously not be doing any work on it myself!
Thanks

 

[Andy™]

what is this machine? if its new, id be contacting supplier about it being faulty

 

[Richard-the-Ninth]

Have you anything else you can try in this socket? and can you plug this machine into a different socket?

 

[Geoff1946]

Who fitted the plug? Five wires so it's worth checking nothing is crossed over.

 

[kerching]

As above and It could be a contactor pulling in and lines connecting at different time to Neutral . Seen that a few times
Remember single phase will kill you
3 phase will really really really kill you
Both will hurt whilst it is happening
No amount of screaming will make it stop of its own accord

 

[Rp74]

Thanks for the replies.

Its a dust extractor. I got it second hand but is almost new & I know it was running fine before I got it.
The plug was already fitted but I've checked the wiring and its as it should be.

I had a problem with the rcd tripping before, it only ever happened with my 240v tools and never the 3 phase machines but I had it replaced and has been fine until now.

 

[Andy™]

youll need an IR tester to check it. its possible the motor is faulty, always has been and there was not an RCD at the other place. its also possible thats its been damaged in transit

 

[sparkey999999]

is there a speed control or soft start fitted to the dust extract?
VSD,s & soft starts have internal leakage built in to the unit and can trip a RCD

 

[Rp74]

is there a speed control or soft start fitted to the dust extract?
VSD,s & soft starts have internal leakage built in to the unit and can trip a RCD

No speed control, not sure about soft start but don't think so.
I think I'll drag it across to another workshop and see if it runs over there

EDIT Just checked, its an induction motor

 

[Mike.J]

Is it fitted with an induction motor, the start up loads on some of these is sufficient to trip a normal RCD/MCB you may need to change one or both for a motor tolerant one i.e. a B curve to a Motor rated C curve.

 

[Sidewinder]

An RCD to IEC 61008 which the OP is suggesting they have, doesn't have a current curve in the sense of, B, C or D.

 

[Rp74]

Is it fitted with an induction motor, the start up loads on some of these is sufficient to trip a normal RCD/MCB you may need to change one or both for a motor tolerant one i.e. a B curve too a D curve.

Cheers Mike

The socket is wired to a HBA B32 breaker which doesn't trip. The incoming feed comes through this RCD which is what's tripping. Would you suggest changing either/both?
Just tried the extractor in another workshop and its working fine so definitely looks like mines the problem.

 

[Luckyboy]

It is most likely the start current, fit a delayed RCD (S type)

 

[Mike.J]

I have a three phase supply in my workshop and had to put a D curve MCB to stop the one phase socket outlets from tripping, this is in France so may be a different designation here in the UK, look for a motor rated MCB: https://www.tlc-direct.co.uk/Products/WYNHXC16.html French MCB's are dual pole, but a single pole one as above should work, please also be aware that you Earthing may not be up to the requirements to ensure a 30ma cut off, I put in a separate Earth rod for the workshop.

 

[Fleeting]

I have a three phase supply in my workshop and had to put a D curve MCB to stop the one phase socket outlets from tripping, this is in France so may be a different designation here in the UK, look for a motor rated MCB: https://www.tlc-direct.co.uk/Products/WYNHXC16.html French MCB's are dual pole, but a single pole one as above should work, please also be aware that you Earthing may not be up to the requirements to ensure a 30ma cut off, I put in a separate Earth rod for the workshop.

The rcd in question has no type characteristics so this is not relevant and not the reason it is tripping. Nothing in this post is relevant to the OP.

 

[Andy™]

It is most likely the start current, fit a delayed RCD (S type)

maybe back to college for you. MCB tripping charastics & RCD tripping are completely different. S type will NOT solve this, and since the RCD is probably there for additional protection, then fitting an S type will not be compliant as its trip times will be too high (and i dont think you can get a 30mA S type anyway since they have no use)

 

[Andy™]

I have a three phase supply in my workshop and had to put a D curve MCB to stop the one phase socket outlets from tripping, this is in France so may be a different designation here in the UK, look for a motor rated MCB: https://www.tlc-direct.co.uk/Products/WYNHXC16.html French MCB's are dual pole, but a single pole one as above should work, please also be aware that you Earthing may not be up to the requirements to ensure a 30ma cut off, I put in a separate Earth rod for the workshop.

its not tripping the MCB. so what use would changing the MCB type be? useless and irrelevant 'advice'. and there's also a fairly good chance that a D type will not meet Zs either

 

[Andy™]

Cheers Mike

Just tried the extractor in another workshop and its working fine so definitely looks like mines the problem.

does the other workshop have the same setup with 30mA RCD on the socket? if not, then youve proved nothing. its also possible that even if it is, there isnt anything else there leaking a little bit to earth that in total at yours is enough to cause it to trip. the only way youre going to find the cause is getting it tested properly with an IR tester. randomly replacing parts as other muppets have said, and taking it for a trip to other places to try plugging it in, isnt going to be much use

 

[Mike.J]

Thanks you Miss Piggy.