Motor contactor not holding in

[dan.taylor.1]

Hi folks,

My union pedestal grinder is playing up. Basically the contactor isn't staying in, and in fact won't start from the start button at all, it only works when you open the front and manually push the central bit in, at which point the motor fires straight up and runs as should, but as soon as you let go it turns off, am I looking at a new contactor or is it worth pulling apart to have a look?

Pic attached, its quite old and fits inside the machine not on an external box, and would need to be like this again or you couldn't stand at the front of it!

Cheers, Dan

 

[Seadog]

Burnt out coil by the sound of things.

 

[frank horton]

also check the connections....
they can loosen with vibs.....a friend who was a high voltage electricien said check all connection at least once per year.....
that was my job every Booxing day morning....
one of the contactors in my Bridgeport did the same......managed to save it from burning the con/wires.....
it will be rewired v/soon with all new contactors and lighting....

 

[Munkul]

check voltage to the coil when pressing on button, if that's good then the coil is burnt out.

 

[daleyd]

Has it got an overload as well ( looks like on bottom right??) may be that, but a bit of checking with multimeter should point you in right direction. What’s the coil voltage?

 

[brightspark]

apart from knacked coil check for continuity across the white stop switch terminals on the overload. should get it without it being pressed. you will be very lucky to source a coil for that if its knacked

 

[JimmyS]

I take it you have you checked that the overload hasn't tripped - if its on manual reset?

 

[m_c]

As has been said, check for power reaching the coil.
If it's not, you need to chase the power.

Although if the overload can be manually triggered, it's probably worth triggering it a couple times, before digging out the multimeter, as the contacts may have become corroded enough to lose continuity if it's never been tripped for a long time. A few operations can often revive contacts, although it's better done with them under power, as the arcing helps clean them.
Failing that, out with the multimeter and chase the power.

 

[Brad93]

Strip it out. More hassle than they're worth them old contactors