Thread: Breaker trip

Ahh, yes! Had a similar problem with my belt and disc sander, which led to the contact supports in the switch being annealed. No easy way back from there, just throw it out!

Hi Everyone,

I know this thread is getting on a bit, but I have a similar thing happening with my DC (Jet DC 1200). Quite some time ago I noticed that the DC would very occasionally trip the RCD on the switchboard when it was switching off. But within the last few months it has been tripping the RCD unit when I switch it on, once again very occasionally. After I reset the RCD it will start ok. I should point out that it only ever tripped the RCD but not the associated circuit breakers.

Up until recently, the said RCD had 2 light circuits + 2 power circuits connected to it. The 2 power circuits connected were as follows
Circuit 1. powers all of the 10A power points in the shed.

Circuit 2. powers only the DC.

Last week I had my electrician remove the RCD & install 4 separate RCBOs. One for each of the light & power circuits to try to eliminate where the fault was as well as stopping the lights being thrown as well as power. However now I find that the DC trips the respective RCBO almost every time no matter which power circuit I plug it in to. So I guess that the fault lies within the DC.

The JET DC has a 2HP motor, 8A rating.

I have been following all of the above threads as well as other threads for a long time but have not found a solution as yet. I have also given the information to my electrician for a read and he's coming back next week to check the DC motor & take some readings. I've checked inside the DC switchbox & everything seems to be in order.

Any suggestions or help would be very welcome.

Regards

Alan

There are various time based sensitivity RCBO's - if he has selected breakers of a type that are too time sensitive then they turn off too quickly then the start up current required by a 2HP DC (>30A for a couple of seconds) will trip these units. Ask the sparkie what type or class the overcurrent rating is for the RCBO. If they are type/class B then maybe go for a Type C.

On the DC another source of problems is the centrifugal switch inside the motor.

BobL
Thanks for the quick reply. Yes I will check with him this week re. the RCBO's.

I did replace the RUN capacitor last year as it was tested as faulty. The top was cracked open.

Regards

Alan

BobL

My electrician came yesterday & installed a Double Pole Power Point on one of the 10A circuits.
1. plugged DC into DPPP switched on - Tripped RCBO
2. plugged DC into SPPP on same circuit & switched on - Tripped RCBO
3. plugged DC into dedicated 10A DC circuit & switched on - Tripped RCBO

This is only happening intermittently - It may switch on ok for 3 or 4 times & then for the next couple of times it trips the RCBO. (I don't normally keep switching the DC ON & OFF repeatedly).

We plugged the DC into a 15A circuit with a 20A circuit breaker (NOT RCD PROTECTED) & didn't have any problems.

The RCBOs installed are HAGER ADC 320T C20 - 20A "C" curve. My electrician followed up on your suggestion of a different time based RCBO with the electrical wholesaler with the result of

1. They would have to source them as they have had very little requests for them in the past.
2. They didn't give a price but suggested that they could be very, very, expensive.

The motor test results are

1. START current - 36A for about 2 seconds
2. RUN current - 7.4 A

My next step is to replace the START capacitor so as to eliminate it as a problem even though it was tested as ok last year.

Bob, it seems strange that with such a large number of these units in use, no one else has mentioned having similar problems to mine.

I would be interested to hear from other owners of this unit (JET DC 1200 C - 2007) whether or not they have it connected to a circuit that is RCD / RCBO protected, & if they have experienced any issues.

Thanks in advance for your help.

Regards

Alan

Originally Posted by Little Boxes

This is only happening intermittently - It may switch on ok for 3 or 4 times & then for the next couple of times it trips the RCBO. (I don't normally keep switching the DC ON & OFF repeatedly).

Alan

Welcome to my world, I have exactly the same issue when I turn on my three phase VFD that drives the cyclone and I can't find the problem and sometimes it does not happen for weeks.

Originally Posted by Little Boxes

BobL

My electrician came yesterday & installed a Double Pole Power Point on one of the 10A circuits.
1. plugged DC into DPPP switched on - Tripped RCBO
2. plugged DC into SPPP on same circuit & switched on - Tripped RCBO
3. plugged DC into dedicated 10A DC circuit & switched on - Tripped RCBO

This is only happening intermittently - It may switch on ok for 3 or 4 times & then for the next couple of times it trips the RCBO. (I don't normally keep switching the DC ON & OFF repeatedly).

We plugged the DC into a 15A circuit with a 20A circuit breaker (NOT RCD PROTECTED) & didn't have any problems.

The RCBOs installed are HAGER ADC 320T C20 - 20A "C" curve.

In that case its not the breaker but the RCD side that's the problem
I know your sparky won't like it but I would be trying a different brand of RCBO.

Bob, it seems strange that with such a large number of these units in use, no one else has mentioned having similar problems to mine.
I would be interested to hear from other owners of this unit (JET DC 1200 C - 2007) whether or not they have it connected to a circuit that is RCD / RCBO protected, & if they have experienced any issues.

That's why I suggest trying a different brand of RCBO.

Something else to look at is this website.
Marc's Technical Pages: Power Quality Symptoms and Solutions - Nuisance Tripping

CHRIS & BOB L

GOOD NEWS - Hopefully, the problem is solved.

I spoke to a motor rewind electrician last week & he has found that these faults often result from the CS contacts arcing across to the motor casting.

So I removed the 1. Fan Casing 2. Fan 3. CS protection cover 4. CS & contacts.

This revealed that the CS contacts had been arcing across to the motor casting causing the RCBO to trip. You can see the burn marks in the photos. ( Soon )
This happens when the contacts switch from CLOSED to OPEN, as there is a quite a BIG spark happening then.

His suggestion was to place a piece of insulation material between the contacts & motor casting.
Firstly I used a piece of gasket material which did not work, but then obtained a piece of proper insulating material from him which has fixed the problem.

I have been using the DC every day for about a week now without any problems.
Hopefully this has been the solution.

Would someone be able advise me on how to resize photos for posting ?


Regards

Alan

Good news with the tripping problem, one day I will find the problem that is causing my earth leak detector to trip.

Photos can be re-sized in paint if you are using Windows, if on a Mac I have no idea. Open the photo in Paint and there is a re-size menu icon in the tool bar, click that and you have two choices, pixels or percentage, choose pixels. resize to about 800 pixels in the first box and the second will scale to size automatically. Save the image and upload that to the forum and it will be a small thumb nail. Be aware that saving the image changes the original image so if you want to save the original image make a copy and re-size that. If you find the image size too small just increase it gradually to what suits you.

Originally Posted by Little Boxes

His suggestion was to place a piece of insulation material between the contacts & motor casting.
Firstly I used a piece of gasket material which did not work, but then obtained a piece of proper insulating material from him which has fixed the problem.

Glad to hear it has been sorted and its something else to stash away i the possible fault list.
A HV megger test would probably have picked up this up.

CHRIS & BOB L

Thanks for your help. Here are the photo's

Dust collector 022.jpg Dust collector 021.jpg Dust collector 020.jpg Dust collector 019.jpg Dust collector 018.jpg Dust collector 017.jpg Dust collector 016.jpg


Regards

Alan

Alan, were these taken with a phone?

Thanks for the pics.

Most of the Centrifugal switches I have seen have been as "intimate" with the motor casing as this one.

I take it you replaced the "Grey insulating material" with something better?

Another reason why 3P motors are better than SP motors.

CHRIS
Yes I took them with my Samsung Note 4 phone.

BOB L
Yes, I replaced the "grey gasket material" with "proper semi-transparent hard plastic insulating material" that the motor rewind electrician gave me, as the grey gasket material didn't work.

Not sure what the name of this material is.

Regards

Alan