Machine only runs when the start button is kept pressed down

[Blobber]

Would be worth checking the limit switch as well, I think that o/l in the motor is just an over temperature thing

 

[daleyd]

Would be worth checking the limit switch as well, I think that o/l in the motor is just an over temperature thing

I think with the limit switch not made even with the button pushed the coil wouldn’t pull in as it’s in series with the coil if you see what I mean?

 

[Blobber]

I think with the limit switch not made even with the button pushed the coil wouldn’t pull in as it’s in series with the coil if you see what I mean?

Your correct but I was thinking more of it being made when the machine is off and as soon as its started the vibration is causing a break somewhere? what does the limit switch do? shame 5mins with a multimeter and it would be a doddle to sort

 

[daleyd]

Your correct but I was thinking more of it being made when the machine is off and as soon as its started the vibration is causing a break somewhere? what does the limit switch do? shame 5mins with a multimeter and it would be a doddle to sort

Ah maybe, yeah a multimeter would find it pretty sharpish.

 

[James Paul]

I put the bridging wire across the black and brown wires and the planer ran normally again. I then took the motor out of the machine which gave me a better look inside the box with the wires in (see photo). Is this the overload device?

 

[Ubique]

Looks like a thermal fuse, not anything self-resetting though, they are typically bi-metallic. It looks like one end goes to the black wire, if the other end goes to a brown wire, then that is the cause of the issue.

 

[Ubique]

May be worth contacting http://www.ottercontrols.co.uk/cutouts.html#gsc.tab=0 and giving them a copy of the circuit diagram and motor rating etc. to see what they recommend you replace it with and crucially where to locate it. shouldn't be expensive but you definitely need some form of overload protection, most 'modern' contactors (I remember them from the '80's at least!) had an overload cut-out device connected in series, I'm not sure if you would be able to accommodate that type in your control enclosure.

 

[James Paul]

is that thermal fuse likely to be the only protection? I have attached another photo. I joined the 2 broken wires to see if there would be continuity between the black and brown wires in the connector on the right of the photo - there wasn’t any. Should there be continuity there.
Is there a way to confirm that this blown fuse was why the machine wasn’t running, before I put the motor back in.
I will contact otter controls. Thanks.

 

[Ubique]

There is the device marked 'n' next to C2, it's possible that is the thermal fuse but it's not a symbol i'm familiar with. you need to be following wires to get to the bottom of things, although the thermal fuse you've bridged out has definitely failed! The motor is an induction type so there won't be any brushes etc. pinging out if you take the end caps off to have a look inside.

 

[James Paul]

It’s definitely worth having a look while I have the motor out. I’ll post here again when I know more.

 

[Ubique]

Looking at the photo again, it could be a wirewound resistor, I'm not too familiar with the in's and out's of dual capacitor induction motors so I wouldn't have a clue if it is, or what value it'd be.

 

[skotl]

There is the device marked 'n' next to C2, it's possible that is the thermal fuse but it's not a symbol i'm familiar with. you need to be following wires to get to the bottom of things, although the thermal fuse you've bridged out has definitely failed! The motor is an induction type so there won't be any brushes etc. pinging out if you take the end caps off to have a look inside.

That is a funny looking thing. I presume that C2 is definitely a capacitor in which case it reads to me that a combination of C1 and C2 keep the coil energised at switch on through a potentially long or intermittent feed from the switch.
I'm not sure why anything around C2 would stop it latching

I might be missing something, but where is the burnt out component in the circuit diagram?

 

[Alan Reynolds]

Thermal fuses are usually mounted in contact with something like the transformer windings. The fact that the heatproof sleeving is burnt suggests that the device might be a resistor.

 

[Ubique]

I'm guessing it is 'n' - purely from the photo's and particularly the one of the thinner black wire disappearing inside the motor housing.
And it wouldn't stop the coil latching - only the device between the black wire and the brown wire marked 'ol' would do that.

 

[skotl]

Am I the only person thinking "rip the whole kit and caboodle out and replace it with a £12 15A NVR"?

 

[Alan Reynolds]

Could it be an inrush resistor? That would be around 10 ohms. Sometimes in series with the fuse.

 

[Ubique]

It's possible one is acting as a run capacitor and the other as a start capacitor, It could be that one of the capacitors is failing and causing excess current through the resistor - replacing the control circuit with a NVR won't fix that.
@James Paul are both capacitors the same rating & value?

 

[daleyd]

Looking at the diagram I reckon “n” is a centrifugal switch.

If you zoom in you can see it drawn as acting on a normally closed contact

 

[James Paul]

Here’s a picture of the capacitors

 

[awemawson]

n being an indication of speed sensitivity - n revs per min - perhaps