Single phase motor wiring - help!

[georgemharris]

Hi folks,

Long time lurker and reader, first time poster.

I've got a new motor for my P/T after the last motor melted its winding.

It's an Axminster model AH106, and Axe sent the replacement motor. But they sent a different type (even though it's got the same part number, and is rated the same, and they have admitted as much, but have also not offered anything different) and are being very reticent in giving me the wiring diagram, probably so they don't have to take responsibility for when it goes wrong.

I've got a pic of the old wiring, and of the new. The new type has a thermal protection circuit (probably an upgrade given what happened with the last one - only 4 years old - . I know that I need to wire the protection circuit in series in some way with the main winding connections, but don't want to randomly assign wires and have a crack at it!

Any help will be welcomed, I'll bring the motor home so I can do things here, where I've got internet over the coming festive period.

Thanks in advance
George

Pic sent me by Axi

 

[Myfordman]

No you absolutely do not want to wire the thermal sensor in series with the motor. If you have an nvr switch on the machine that is designed for a thermal sensor, it connects there and no where else. If in doubt leave it out and just wire power to the blue and brown terminals.

 

[niall Y]

Ideally you need the wiring diagram for the updated machine. I'm surprised that Axminster have not supplied this. Connecting it as before to the blue and brown terminals will give you a working machine, but one just as likely to burn out again.
.No doubt you have paid extra for this new feature in the replacement motor. Surely Axminster should at least give you the courtesy of supplying enough information for you to make use of it.

 

[Spectric]

The new type has a thermal protection circuit

Don't confuse this device with overload protection, normally the thermal protection is a thermistor that is within the windings and is just a sensor that is wired back to a motor protection relay to detect a rise in temperature within the windings and cannot carry the motor load current. As has been said you will be better of to just connect the live and neutral because the machine is probably not designed to interface with the thermistor, to make use of this may require a different NVR and control wiring.

 

[Dabop]

It should be clarified that if the diagram from them is correct, they are NOT talking about either thermal sensing, or overload protection...
They said a reset-able thermal protector (as opposed to the non resetable ones- which basically are a single use device- like a fuse but 'blows' with temperature rather than current)

And yes- if it is one of these, then it needs to be in series with the Active (brown) incoming mains connection...
Self resetting ones are quite common... usually found 'buried' in the windings for those of us that have rewound motors (not one of lifes great joys may I add)

Although it would be nice of them to actually clarify what they provided...
(at worst you could indeed just 'hook it up' without the protection in circuit- but it will likely suffer the same fate- they added thermal protection for a reason lol ie the motor is undersized for the job...)

 

[Spectric]

Well spoted @Dabop yes it says "reset type thermal protector" which is just a bi metalic device that is wired in series..

 

[Dabop]

Done a few (lol) motor and alternator rewinds over the years...
Just a few....
(I used to actually rewind car alternators while watching movies on TV as an apprentice elec fitter for the extra $$$- my wages as a first year apprentice were under $100 a week....)

A dying art these days, practically no-one rewinds things any more

 

[Spectric]

A dying art these days, practically no-one rewinds things any more

Part of the throwaway world unfortunately. I can remember a company who handled all the pumps for Anglian water and performed many a rewind but I dare say they just replace like for like thesedays. Must say I have not heard of anyone rewinding a car alternator, we used to just fit a new stator if needed and this was the same for commercial alternators like the A100 from Butec and rewinding a car stator must have been hard on the old fingers.

I think the only time anything gets wound now is with specialised inductors and ferromagnetic cores for SMPS's and only if they cannot be brought in .

 

[georgemharris]

What an awesome series of replies.

Super impressed with how you guys are on it so quickly, and have offered an absolute wealth of information way over and above what Axminster offered.

I’ll try wiring it without the protection circuit just to get it running, and then I’ll try the protection circuit in series with the brown wire and feedback here with some results.

Thanks once again, report back soon.
George.

 

[Sideways]

On the motor pictured to the right - the new one I take it - the pair of white wires are similar in thickness to the others.
This isn't a guarantee, but thermistor sensor wires are often thinner than the leads to the motor coils because they don't carry any significant current. Thicker wires suggest the white wires are intended to carry a real current.

 

[Sideways]

The other thing is just measure the resistance between the white wires. A resettable bimetal switch should have a resistance of 1 or 2 ohms at most. Ideally less.
A thermistor sensor will have a much higher resistance.

 

[georgemharris]

Hurrah! The machine lives again!

Tested as described above. No resistance in the thermal cutoff circuit. Wired in series with main wiring, turns on, runs, lovely!

 

[cmoops2]

In the last photo, is the capacitor shorted (red link) ?

 

[Dabop]

Part of the throwaway world unfortunately. I can remember a company who handled all the pumps for Anglian water and performed many a rewind but I dare say they just replace like for like thesedays. Must say I have not heard of anyone rewinding a car alternator, we used to just fit a new stator if needed and this was the same for commercial alternators like the A100 from Butec and rewinding a car stator must have been hard on the old fingers.

I think the only time anything gets wound now is with specialised inductors and ferromagnetic cores for SMPS's and only if they cannot be brought in .

It's actually not that hard- depending on the alternator involved, the enameled copper windings in the stator were only around 1mm-1.5mm wire, and they really are easy to do- cut the plastic 'liner' for each slot to size with scissors, rewind like for like (number of turns etc), fit another plastic liner 'cap' and then pin that down with a wooden dowel (think like a matchstick but slightly bigger) tapped in with a small mallet, heat the entire thing up in the oven, and dunk it into a hot pan of winding enamel on a stove burner, then hang to dry overnight...

I would usually do at least two while watching a movie on TV, get $20-$25 each for them (big money when your paypacket was under $100!!!) easy money for a elec fitter apprentice lol

Rotors were harder as you need a press to open the 'claws' up (but easier to actually wind)

 

[Dabop]

In the last photo, is the capacitor shorted (red link) ?

It does look like it doesn't it???
old and new motors from earlier post- they appear to dive into a hole into the housing

At first I thought the same when you said it!!!

but a closer look shows it is two red wires (seriously???) both diving into the sleeve...