The Shop > Tools
X3 Milling machine Motor Overheating and tripping house RCD
raynerd:
Stuart - thanks for the advice.
The motor is REALLY hot. It was only running for about 2/3 minutes on a very slow speed before it tripped and it is so hot you can not put your hand on it. This surely isn`t normal. I can`t smell any burning but it can`t be far off.
I`m not too sure with regards to a mains filter - there are three fused trip switches in my garage which are NOT blowing and it is blowing the house main trip switch and killing all the house electricity (it is not even tripping the "garage" fuse on the main board).
Sid & Kjelle - thanks also for your input. The googling I did last night also suggested a leak to ground with others having a similar issue. I`ve only a basic understanding of the DC motor as I`ve never opened one. What exactly am I looking for and is there any way to test the motor is leaking to Earth? Could the brushes be the issue?
I know there are lots of posts about the boards going dead and killing the machine - I presume if the board was dead my motor would not run at all or could it still be a board issue?
I`ve not much experience with motors and I`ve come on here for help but the more I think about how stupidly hot it was, the more I can`t help think that that is the issue. Could a leaky motor also cause the heat issue.
Any more advice as to what I could do tonight when I get home to test and check everything would be much appreciated!
Chris
lordedmond:
Chris
The filter if present will be in the mills elect box small shiny thing
Small earh leaks will not trip/blow a MCB/fuse but a small leak will do the RCd
If it's that hot and the magic smoke is still in , then you need to isolate the problem
Is this a old style one you can see the brush holders on the motor , it will only have two wires going to the motor or is it a new style one with a brushless DC motor, these have more than two wires because of the feed back Hall effect devices ,a quick squint at ark's site may help
Slip off the belt and run it off load see how it goes it should spin very freely
If you have a brushed motor you can ( turn off and unplug) take th out for inspection , but do not remove the end cap unless you mark its position very carfully as its rotation position is critical for the brush magnet relationship
If it's a brushless one you can do the same off load test but I have no knowledge of these ( I know how it works but not had my mitts on the insides of one
As you know diagnostic of the web is difficult but the off load test should split the problem from electrical/mechanical source
A note I had a early X3 not from ark that got hot and released the magic smoke and that was a duff motor
Stuart
raynerd:
It is a brushed motor.
I`m sorry for such a basic question but what exactly can I 'inspect' on the motor? I.e would would be your process?
So I can easily remove the belt and pull the motor assembly out of position. I can remove the bushes and check those - I`ve never actually checked brushes before so do they wear down. A new one is apparently 6x12x18 so I guess if it is worn it could be an issue? If the brushes look good - then what should I do. I`ve never removed the end cap so do I mark it position on the outside in relation to the lower main body section?
Sorry - I`d just rather know what I`m looking for. It hasn`t smoked yet so I`m guess it can still be rescued or is the best bet to just replace the entire motor?
EDIT - I may be totally wrong but I can`t help thinking it all tripped when I touch the machine itself! It was running OK when I was only touching the hand wheels - it could be my imagination. I`ll try and assess tonight!
lordedmond:
Chris
You have me worried
It tripled the RCd when I touched it .
Ok let's go though it one step at a time
Make sure the earth lead ( machine to 13 a plug ) is sound test with meter by thi I mean test from the metal parts of the mill to the earth pin .
If that's ok the you need to check or have checked the earth conductor in the socket , back though to the house consumer unit , because it sounds to me that it's not correct .
The above is very important and needs to be done
Now on to the brushes you remove the plastic cap and the brush should just pull out nicely , quite free as you know the new size you can make an assessment on that , they should not be chipped but look like they fit the commutator nicely
Chris take care
Your situation is why I am of the old school with bonding , I have a 10 MM. earth conductor connected to all the machines independent from the power cables an this is bonded back to a 2 metre earth rod that is also bonded back to the consumer unit in the workshop , this is then bonded back to the house consumer unit and then to another earth rod
As I had acces to the test gear to prove all this I know it's ok the reason for all this is to make sure that all the metal you can touch with both hands ( eg across your heart ) is at the same potitential
Run the motor off load and see what happens but until you are sure about the earthing put som marigolds on :D
Stuart
Chris
If you do not have one of these I recommend yo get one they are not expensive
http://www.amazon.co.uk/13-Amp-Plug-Socket-Tester/dp/B004BLPIBK
Other site do have them as well well worth a check round now and then for peace of mind
John Rudd:
Chris,
You can disconnect the motor altogether from the controller and in its place wire a 100watt domestic light bulb....if the rcd/breaker stops tripping, my money is on a leaky winding on the motor to earth.
This can be checked with a megger/insulation tester, ( but I doubt you will own one... :lol: )
A new motor I'm afraid....
Stuarts advice on wearing rubbers is good, you could also stand on a rubber mat too if you have...
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