I've got a 3 phase lathe and its tripping when you turn it on. There's a bright blue flash/spark coming from the switch wiring. I've done the general checks on the wiring to see if any of it is bare but all looks ok. Anyone clued up on these types of thing? Can I bypass the switch to see if it's the actual switch?
I'm sure there are many specialist electricians on here who'll be along shortly, from my experience you are right to suspect the switch itself as worn or "dirty" contacts will produce a flash for certain.
Sounds like you may have a short across phases or the earth in the wiring or motor. Disconnect the motor at the connection box, take a photo of which leads connect to each terminal. Before removing, tape up the tail ends and try the switch if it still sparks the problem is in the lead. Use a multimeter to check the motor continuity.
Isolate, have a look for anything obvious, get a qualified man in. When was it last used? Have a smell at the motor, if it's burnt out it will tell you.
All good advice, the best being "get a man in". 3-phase is 600Vac peak to peak and will throw you across a room. If you are a young man you may survive (as I know). Q. Was it working recently? Q. Has it been rewired/moved? Once isolated check each motor phase to earth and then each phase to each other. All should be 100% open circuit. Q. Are all three phases present? Quite common to loose a phase, like a one third power cut. Check you have 240Vac between each phase and earth, then 415Vac RMS between each phase to each other.
Thank you all for advice. I'm quite a sensible chap, so advice on getting shocks etc are not necessary... but thank you for caring @AirCon All good advice, the best being "get a man in". I'm not a fan of getting a man in straight away, as it could be something very simple 3-phase is 600Vac peak to peak and will throw you across a room. If you are a young man you may survive (as I know). As above, not necessary to point this out as I'm fully aware of the dangers etc, and frankly, not that bothered, if it's my time, it's welcomed. Q. Was it working recently? I bought it from a place that had been using it and when I got there, the guy was very apologetic and saying he went to try it and it wasn't working Q. Has it been rewired/moved? It has been rewired and tested/certified and the guy doesn't know why it isn't working... or isn't telling me Once isolated check each motor phase to earth and then each phase to each other. All should be 100% open circuit. Tested and all are fully open circuit Q. Are all three phases present? All three phases present and correct Quite common to loose a phase, like a one third power cut. Mo phasing occuring Check you have 240Vac between each phase and earth, then 415Vac RMS between each phase to each other. I will check this tomorrow Much appreciated for you to take the time to reply
Have you just purchased this lathe And tried to connect to your domestic supply (single phase) or has it been running previously With a three phase supply? For what it’s worth My first lathe was a boxford with a three phase motor. This motor had the facility to change the winding arrangements ( from memory it’s star to delta or something like that- it’s a good few years so you will have to do your homework!) this allows you to run it from a single phase. The next issue is it’s designed to run on 400volts. You now need to buy an inverter which with cleaver electronics allows you to run it from a domestic single phase. About 120 quid from memory. I would suggest model-engineer.co.uk website as I pretty sure this has been covered in some detail. Hope this helps - if not excuse me for getting the wrong end of the stick!!
It's a good big lathe, Chesterfield I think. Was running on 3 phase in previous workshop and on 3 phase in my unit. You'd have to stick a zero on to that price for a good 7hp Transwave inverter now.
Q. Can you manually rotate the motor, say with a spanner? If the phases are swapped then it would ....... answers on a postcard.
"It could be something very simple..." True - but it could also be something very fatal. Get an electrician to look at it.
I’m a spark.....or at least I qualified as one many many years ago so haven’t been in the game for a long time. There will be some form of starter button which activates a contactor - check both sides have supply power and when energised the power is present on the other side. If that’s correct I’m assuming there is some sort of speed controller?
