electrics

[sue denim]

Hello

I have recently acquired a three phase planer thicknesser which is wonderful. Problem is this. After a few minutes operating it trips out the 30ma trip.

Any ideas why ?

'Sue'

 

[MMUK]

What's the motor current rating? What's the trip rating? Trip curve? Are you running from a 3 phase supply or an inverter?

 

[Myfordman]

If the trip is 30mA then it is an RCD. and nothing to do with the motor load current etc
The cause of the trip is a leakage to earth. Either caused by the machine or the sum of total leaks in the system has exceeded 30mA.

MM

 

[sue denim]

sounds expensive...

 

[ColeyS1]

Could just need a different rcd. 10-20 quid was all it took to stop our compressor throwing a wobbler

Sent from my GT-I9300 using Tapatalk

 

[sue denim]

A replacement rcd was suggested unfortunately it's not 20 quid....it's 120 euros !

I am cautious spending 120 if it doesn't solve the problem.

Thanks so far

'Sue'

 

[Paddywack]

I know this might sound a daft question but have you got enough electricity coming in?

 

[CHJ]

Can you take a drive belt off and see if the motor starts and runs without a load?

That will at least prove the problem is not a short circuit in windings or to machine case.

 

[MMUK]

If the trip is 30mA then it is an RCD. and nothing to do with the motor load current etc
The cause of the trip is a leakage to earth. Either caused by the machine or the sum of total leaks in the system has exceeded 30mA.

MM

All of my questions are perfectly valid in trying to determine cause. I was fully aware of the fact that it is a 30mA rcd but there's more to it than just saying "earth leakage. Replace the trip". Knowing the supply and motor characteristics make a great deal of difference.

Sue, what rcd have you been quoted for? 120€ is damned expensive!

 

[sue denim]

For mmuk

Errr...... It has a switch and a huge beast of a three phase motor...

3kw or 4.5 depending on something....not sure what but the planer does have two speeds 3000 rpm or 6000 rpm.

It is 5hp and doesn't have a step up starter.

The rest is a mystery to me.

I should have enough electric coming in.

It is real three phase, not an inverter..

There you go that is everything I know. 'Sue'

 

[Myfordman]

If the trip is 30mA then it is an RCD. and nothing to do with the motor load current etc
The cause of the trip is a leakage to earth. Either caused by the machine or the sum of total leaks in the system has exceeded 30mA.

MM

All of my questions are perfectly valid in trying to determine cause. I was fully aware of the fact that it is a 30mA rcd but there's more to it than just saying "earth leakage. Replace the trip". Knowing the supply and motor characteristics make a great deal of difference.

Sue, what rcd have you been quoted for? 120€ is damned expensive!

I was not the one suggesting replace the trip as it happens. Analysis is what is needed before shelling out cash.

Sue is based in France where there is generally little price competition encouraged. My 2007 French catalogue from a DIY shed shows Legrand 3 phase RCD at 157 Euro.
Getting a tradesman with the right analytical skills can be very difficult in France let alone actually getting them to turn up quickly.

I'll leave this one to MMUK who clearly has superior skills in this field.

 

[sue denim]

thankfully I have a tame French electrician....

 

[Deejay]

Afternoon Sue

I don't want to tread on anyones toes, and I don't know much about motors, but I know a man who does.

Post on The Wood Haven and Bob (9fingers) will probably be able to help.

Cheers

Dave

 

[woodfarmer]

A replacement rcd was suggested unfortunately it's not 20 quid....it's 120 euros !

I am cautious spending 120 if it doesn't solve the problem.

Thanks so far

'Sue'

Go to your nearest Brico Depot. they are usually the cheapest about.

But I suspect it likely you have an earth leak somewhere. The other thing is the starter may be the problem. or if the motor is run star connected there may be an imbalance in the windings causing the system to trip.

 

[MMUK]

Ok. What's the current rating of the trip? Start up current dictates you need a 16A trip, obviously a 3 pole one. I would recommend preferably a D curve trip as they aren't as sensitive, however a C curve should do. If this is what you already have then we need to look a little deeper into it, such as how the motor is wired.