I think I have a burned out relay

[Eremius]

I am duplicating this post as I believe this is the proper place for it rather than the original post.

Unfortunately I have run into an issue with the controls. When the start button is pushed the motor will start, run for a few seconds and turn back off. This running period has been getting shorter and shorter.

It is a momentary button push start system with the start button being NO and the stop button being NC.

I *believe* the cause may be a failing relay (M relay on the diagram)

but I have no idea where this little gem is located.

The control circuit is 120v and the power is 220v 3ph.

I know the orange wires go to the start/stop switches. The red/white/black are line 1,2,3.

I am willing and able to provide any additional information as requested.

I am also willing to replace for newer components. This isn't a resto.

 

[den-den]

It looks like you have a 4 pole contactor with the far right pole (lowest picture) most likely being the "M" contact (blue wires).

 

[markba633csi]

The coil is probably going open circuit as it heats- OR one of the other connections is flaky and doing the same. I would first go around and clean/tighten as many of the screw connections as possible and replace any crimps that look iffy- with power off of course
Use an ac voltmeter and check for voltage at the coil when it fails- that would tell you everything. If the voltage is steady then the coil is failing- if not then it's something other than the coil- like the transformer or connections to
-Mark
ps looking closer I do see something funny on the coil like a overheated area or fishpaper coming loose- check that out.

 

[benmychree]

Surely not the overload relays tripping, since they have been jumped with a piece of bare wire ---

 

[Eremius]

The red box or the green box?

 

[Eremius]

The coil is probably going open circuit as it heats- OR one of the other connections is flaky and doing the same. I would first go around and clean/tighten as many of the screw connections as possible and replace any crimps that look iffy- with power off of course
Use an ac voltmeter and check for voltage at the coil when it fails- that would tell you everything. If the voltage is steady then the coil is failing- if not then it's something other than the coil- like the transformer or connections to
-Mark
ps looking closer I do see something funny on the coil like a overheated area or fishpaper coming loose- check that out.

That was my thought as well but I have taken this out, hooked 110 directly to the coil and it locks up.

I greatly appreciate the brainstorming!

 

[Eremius]

Use an ac voltmeter and check for voltage at the coil when it fails- that would tell you everything. If the voltage is steady then the coil is failing- if not then it's something other than the coil- like the transformer or connections to
-Mark

I put my meter on it hit the start button and it started up. The voltage to the coil was jumping all over the place and the coil was dropping out/coming on quickly for a few seconds (15-30 ish) then the voltage straightened up at 127v and no more coil chatter.

Next stop, metering out the transformer?

 

[sdelivery]

Where were your meter leads?
You can put meter leads in many places and achieve many readings.
Looking at this picture I am reminded that there is a color code for wiring for a reason.
If the coil is not maintained when releasing the PB then it's the latch circuit. Poor connections are usually the cause of chattering.

 

[Eremius]

Where were your meter leads?
You can put meter leads in many places and achieve many readings.
Looking at this picture I am reminded that there is a color code for wiring for a reason.
If the coil is not maintained when releasing the PB then it's the latch circuit. Poor connections are usually the cause of chattering.

 

[talvare]

Surely not the overload relays tripping, since they have been jumped with a piece of bare wire ---

I'm sure those are precisely engineered fuseable links

Ted