Treadmill problems again...

[Edtwozeronine]

I first had issues about 6 months ago with my second hand treadmill tripping the ring part of the way into a session, since then I've sent off my controller board to treadmill doctor co uk. He repaired the board and sent it back after approximately a month.

Since then I've had the a dedicated circuit installed with a 16a RCBO so that if tripping occurs with the treadmill again, it will only effect a dedicated socket and not the ring main as well.

Unfortunately, a month into using the treadmill it's tripping the circuit after about 30 minutes of use. In college I learned of type C and type D RCDs and RCBOs that have different tripping dynamics to usual household type B breakers. Do you think one of these could prevent the tripping problem or is it likely to be something else?

Seems this is fairly wide spread problem having searched the interwebs...

 

[Edtwozeronine]

So far just tested the treadmill with load (AKA me!) on a 3a fuse, it pinged off at the 24 minute mark at the RCBO in the garage. I'm pretty cream crackered after todays garden werk, so I'll try the 5a fuse tomorrow.

Beep tested the 3a fuse at 0.06 ohms, the saga continues!

 

[GeorgeCooke]

The fuse is still OK? So it is earth leakage causing the RCBO to trip.

 

[Silly Sausage]

The fuse is still OK? So it is earth leakage causing the RCBO to trip.

The real question is ... will an aeroplane be able to take off from a treadmill?

 

[marconi]

I noted that the motor turns easily and all rollers, etcetera are moving freely and the belt has been lubricated.

Have you changed the brushes yet?

My hypothesis is that the motor's insulation resistance is decreasing as it warms up, most markedly when the treadmill is on load (and a significant load at that ).

As a result, the earth leakage current of the motor is increasing with time(temperature) and of course is added to the normal earth leakage of the EMI filter. I guess the motor controller is a PWM type since motor is a PM one.

It is observed that the RCBO does not trip when the treadmill is run unloaded - thus much decreased work by the motor, less Ohmic heating heat, less temperature rise, less motor earth leakage....total earth leakage does not then cause the the RCBO to trip.

When run hot or hotter than designed, a motor's insulation resistance can be expected to reduce over time.

By the by, there may be a secondary effect of high temperature causing the demagnetisation over its lifetime of the motor's permanent magnets - the result would be that a higher armature current would be required to create the same torque...thus more Ohmic heating.....

I think you are at the stage of asking a motor specialist to test out the motor.

Temperature winding correction - Electrical Engineering Centre

When we perform insulation resistance tester,temperature winding effected the accuracy of Mega Ohms reading.The basic theory is when temperature increase,the insulation resistance decrease due to physical factor of material for winding. To get a accurate reading for insulation resistance ( Mega...

www.electricneutron.com

 

[DPG]

Has anyone ever seen Marconi and Sherlock Holmes at the same time?

 

[Pete999]

Has anyone ever seen Marconi and Sherlock Holmes at the same time?

No

 

[static zap]

I'm thinking you need some-one local with some "Insulation resistance kit" to investigate your black dust deposits ... "Don't inhale" - it's not good for lungs.
With keen eyesight may have some tracking happening, as currents vary ,and volts spike a bit higher.
(Strange substance found in early telephone microphones)

Marconi's what to check for images - were a good start.

-If 3A fuse survived a Tripping of power incident ,doesn't look like an overload.

Do the lights ever flicker in the building with any correlation to trip event ?

 

[marconi]

DPG: I acknowledge your generous comparison, but I would prefer to be likened to DCI Gene Hunt. If you watched the TV series (Life on Mars and Ashes to Ashes) his deputy was the gorgeous Keeley Hawes, it was the 70s so no PC, he drove an Audi Quattro (when they were cool) and most of all he was consummate with the ad lib one-liners, viz:

10 best Gene Hunt quotes

Detective Chief Inspector Gene Hunt, played by Philip Glenister, first appeared in the seventies-set BBC police drama Life on Mars and its sequel Ashes to Ashes set in the 80s.

www.telegraph.co.uk

 

[DPG]

The game's afoot Watson!

 

[Edtwozeronine]

I managed a whole hour yesterday on the 5a fuse, i was expecting it to trip... What sorcery is this?

 

[Edtwozeronine]

I noted that the motor turns easily and all rollers, etcetera are moving freely and the belt has been lubricated.

Have you changed the brushes yet?

My hypothesis is that the motor's insulation resistance is decreasing as it warms up, most markedly when the treadmill is on load (and a significant load at that ).

As a result, the earth leakage current of the motor is increasing with time(temperature) and of course is added to the normal earth leakage of the EMI filter. I guess the motor controller is a PWM type since motor is a PM one.

It is observed that the RCBO does not trip when the treadmill is run unloaded - thus much decreased work by the motor, less Ohmic heating heat, less temperature rise, less motor earth leakage....total earth leakage does not then cause the the RCBO to trip.

When run hot or hotter than designed, a motor's insulation resistance can be expected to reduce over time.

By the by, there may be a secondary effect of high temperature causing the demagnetisation over its lifetime of the motor's permanent magnets - the result would be that a higher armature current would be required to create the same torque...thus more Ohmic heating.....

I think you are at the stage of asking a motor specialist to test out the motor.

Temperature winding correction - Electrical Engineering Centre

When we perform insulation resistance tester,temperature winding effected the accuracy of Mega Ohms reading.The basic theory is when temperature increase,the insulation resistance decrease due to physical factor of material for winding. To get a accurate reading for insulation resistance ( Mega...

www.electricneutron.com

Not yet changed the brushes governor! It's finding the right size that's the problem.17mm W by 6mm D by 14mm L the length being what it is worn down to, so no idea about the original length.

Guess I'll hacksaw off the earth pin if that's the boy giving trouble!

 

[marconi]

So, for the 5A fuse at least another 4 one hour sessions. And the same for the 3A fuse. Remember to run it first for an hour 'off load' before each session of running.

Alas, I am not infallible so could be completely off the mark.

Static Zap makes some good remarks on possible causes. It would helpful if you could look at the commutator and brushes and compare them to the guide I pointed you to.

I admire your willpower to use a treadmill - I found them mind numbing.

 

[GeorgeCooke]

Guess I'll hacksaw off the earth pin if that's the boy giving trouble!

DON'T DO THAT. It is a safety feature to protect you. Anyway if you did the plug would not go into a socket. (except some MKs).

 

[DPG]

DON'T DO THAT. It is a safety feature to protect you. Anyway if you did the plug would not go into a socket. (except some MKs).

I think he's kidding George. I'm sure he'll leave the plugtop alone.

 

[Edtwozeronine]

I'm thinking you need some-one local with some "Insulation resistance kit" to investigate your black dust deposits ... "Don't inhale" - it's not good for lungs.
With keen eyesight may have some tracking happening, as currents vary ,and volts spike a bit higher.
(Strange substance found in early telephone microphones)

Marconi's what to check for images - were a good start.

-If 3A fuse survived a Tripping of power incident ,doesn't look like an overload.

Do the lights ever flicker in the building with any correlation to trip event ?

I think the dust was just a bit of carbon brush wear and tear, since the treadmill has it's own circuit - it's the only thing to trip these days! It used to be on the ring on a 32a rcbo, one of the reasons I wanted it to have it's own circuit. No more TVs, Computers or Sound Systems all going off without a moments notice.