lathe tripping power

[davidbrac]

my vicmarc 100 is pulling the main breaker in the workshop. Not when the lathe is running but when the plug is put into the socket. Tested for a earth to live & earth to neutral fault with a mega meter and there is no short indicating.

The circuit is a ring main with a 32 amp breaker, which is staying put. It the main 80/2/307 RCD that is tripping out.

when the circuit is reset the lathe works as it should

Anyone have any ideas what is happening here

[Bryan Milham]

I'll need to ask you some questions.

Do you have anything else on the circuit, something that might have a RF or other type filter on it (electronics are popular for these).

Have you tried any other item in the same socket, electric kettle, great for taking out RCDs or a dust extractor (something else with a motor in it).

If both of them work you may have a problem with your lathe wiring or motor windings. If either of them also cause a trip, the problem is in your line.

Other questions;

Do you live anywhere near a power line or large substation?

Have you added the RCD recently or has it always been there, it might not be the correct rating for the power you draw.

You have a Mega so I'm assuming you understand electricity - have you tested your Neutral line as well?

[Derwent Woodturning club]

If the lathe is proper variable speed, i.e. using a three phase motor and an inverter, I would suspect the inverter. Many of these have an option to run isolated from the earth but if not, and parts of the inverter make contact with anything earthed, they will trip the RCD, due to earth leakage, not an overcurrent situation.

One other thing, if it is an inverter controlled variable speed, be very wary of using a Mega, as they can wreck the electronics.

As the previous poster has asked, has anything else recently been changed?

[TONY MALIN]

Seems odd to me. Presumably this fault has started recently. Has anyone got a circuit diagram? The fault must be a temporary short ahead of the start switch. The fact that it runs OK after resetting the breaker is OK in one sense, but there is always a possibility the fault becomes permanent and could be dangerous.
Please keep us posted.

[YewTube]

Dave

The obvious answer would be - "Stop unplugging it!", but I suspect your inverter boots up when you plug in to the socket and needs to be unplugged to power down.

Can you plug into a switched socket and power up and down with the switch. Most switch socket are double pole. There is no logical reason why this should work but on the other hand there is no apparent reason why it is tripping. What's to loose?

I had a similar problem and this cured it. No idea why.

Good luck

Bill

[davidbrac]

to answer questions yes there is an inverter, and yes l am using a mega but only on the 240 volt setting and only for checking  earth readings.

Re checked meter readings and when you put the meter between neutral and earth at the plug, you get a very slight reading for less than a second. Its very odd.

Bill agree that l should leave it plugged in, however its my demo lathe and l have a few gigs coming up so would like to get to the bottom of it, as tripping a supply at a show can leave a bit of explaining to the onsite sparky.

I will take off the cover and get the make and model of the inverter and see if l can find a manual online, and move on from there.

thanks for help and suggestions

[Paul Hannaby]

Some questions -

Is the socket turned off when you are plugging in the lathe?
Does this happen when you plug in to any socket?
If yes to both the above try this -
Is it possible to run an extension lead from the house so you can plug the lathe into that? If so, does the lathe trip the RCD in the house?

[John D Smith]

Hi David
              I had the same problem when I set up my new Axminster 1416vs I was advised to bypass one of my RCDs I had one in the house on the

 mains board then one in the Garage then one in the Workshop I bypassed the one in the garage and have never had a problem since. I hope this

makes sense.

                          Regards John

[Eric Harvey]

I have my lathe on its own 32 amp breaker so it doesn`t overload the ring main circuit in my workshop,as lathes can pull 17 amps or more depending on their size of motor and if you have other stuff going at the same time it can easily flip out the trip switch,cheers,

Eric.

[davidbrac]

fault is going to be easier to trace now and what l was worried about happened, lathe stopped working at the Cowal Highland Games during a demonstration/have a go session.

Now just got to get the time to take the lathe apart and trace the fault.

[Graham]

You could pretty much guarantee if it was going to happen it would happen at the worst possible time. I wish you well with it.