Allen Bradley contactors

[nickelec]

I'm having an issue with this contactor trying to figure out why it's not switching over any one have information on or experience with these things it's a single pole 120v with I believe 120v coil as well

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[MAC702]

The coil does say 115-120V, if I'm seeing that label correctly.

What happens when you apply a known 120V to the coil with a jumper?

 

[Jraef]

It is a 120V coil. Do you have 120V at the coil? If not, why not? We can't tell where those wires go from here.

What are the blue wires for? You realize they are jumping across the contacts, right? Given the extreme size difference, I'd be concerned that they will burn up.

 

[nickelec]

So the way this contactor operates is as follows
It's on a movable platform that when is docked is supplied with a constant 120v via a bus bar after driving away from the dock the contactor is supposed to kick in and pick up 120v power from an on board transformer that's fed via a separate 3phase rail system.

I put the blue jumpers in just to get temp power for a few receptacles and lights on board.

Where should I have 120 is the coil on the front or in the left rear where the Ted wires are landed I do have 120 on the front two wires

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[nickelec]

I have 120 across the red and white

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[Jraef]

I have 120 across the red and white

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If it's the red and white wires going into the front of the coil, under that blue surge suppressor (assuming that's what it is) with the bar code, then the coil should be pulling in. If not, then the coil is bad / open winding and needs replacement.

 

[Besoeker]

I'm having an issue with this contactor trying to figure out why it's not switching over .....

Switching over from what to what?
Or do you mean not pulling in?

 

[nickelec]

Not pulling in

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[LarryFine]

I do have 120 on the front two wires.

You are testing the coil with at least one terminal disconnected from the wiring to isolate it from the control circuit, right?

If you disconnect the reds, you can test it with the same power source that normally activates it with a temporary jumper.

This is a process-of-elimination troubleshoot. It used to work; something has changed. You need to discover what that is.

 

[nickelec]

Those r hooked to an auxiliary contact trying to determine the purpose of it now .they all tie into this

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[LarryFine]

The point is you need to determine whether the problem is that the source is supplying voltage and the coil is open, or that coil works and the source voltage is missing.

The third possibility is that the problem is mechanical, but you would hear quite the hum if the coil was energized and the armature was physically stuck in the deenergized position.

 

[Strathead]

The point is you need to determine whether the problem is that the source is supplying voltage and the coil is open, or that coil works and the source voltage is missing.

The third possibility is that the problem is mechanical, but you would hear quite the hum if the coil was energized and the armature was physically stuck in the deenergized position.

In post #5 he says he has 120 volts from red to white. so if that is true, I would Check turn off power, disconnect either reds of whites from the coil, and check for resistance with a multimeter. Should read resistance greater than zero and less than open.

 

[Jraef]

Those r hooked to an auxiliary contact trying to determine the purpose of it now .they all tie into this

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That is an older model of an A-B Phase Monitor Relay, it is looking at the Line Voltage to make sure the phasing is correct and the voltage is within tolerance.
https://literature.rockwellautomation.com/idc/groups/literature/documents/in/813s-in002_-mu-e.pdf

Again, the two wires on the front of the coil should read 120V when you want the coil to pull in. If they do not, then something is preventing your 120V from getting to the coil. It might be this Phase Monitor Relay, it might be ANYTHING else ANYWHERE in the control circuit. But as suggested, FIRST eliminate the possibility that the coil is bad by removing the red wires from the coil and applying 120V from somewhere that you know is a good 120V source.

When troubleshooting, always start with what you KNOW, moving toward what you DON'T know. Never start in the middle and try a bunch of random stuff, you will just compound your problems.

 

[jumper]

When troubleshooting, always start with what you KNOW, moving toward what you DON'T know. Never start in the middle and try a bunch of random stuff, you will just compound your problems.

Spot on advise.:thumbsup:

I start at source and then do the divide and conquer method.