Contactor not latching

An Buachaillín Bán · Thursday at 6:03 PM

Hi all.

Is it too early to wish everyone a happy Christmas?

Looking for a little bit of help regarding a contactor.

I got a call to look at a 230v heavy duty mixer/blender in a busy hospital kitchen. It has stop/start buttons and a contactor within the appliance itself. Contactor is a Teco, 3 pole normally open. When I arrived I assumed it was the contactor. Start button wasn't energising the coil. It just seemed the start button wasn't working. I checked it for continuity by pressing it and testing the contactor. All was good in that respect with the start button and also the stop button. When I manually engaged the contactor the appliance ran away fine.

I replaced the contactor, but still nothing. The power side of the contactor seems OK. I have voltage. Just wondering if anyone knows what the issue could be. I replaced the wiring like for like to the née contactor. And the appliance was operating fine all along, with me being the first person to open it up.

I've attached a picture. Not sure it'll help. I have control cables at no.22 of my NC end but nothing in no.21 NC. Is that normal?

Thanks in advance.

James · Thursday at 6:47 PM

are you getting voltage to the coil when you press the start button?

also, it would be normal to use a N/O contact for the hold in loop, are you sure the contactor is a direct replacement?

An Buachaillín Bán · Thursday at 10:05 PM

James said:
are you getting voltage to the coil when you press the start button?

also, it would be normal to use a N/O contact for the hold in loop, are you sure the contactor is a direct replacement?

Thanks for the reply. I tested across.my A1 and A2 and didn't get voltage reading there when pressing start button.

I also thought that it would've been a normally open contact, but as sure as day it was a NO contactor that I removed. Exact replacement.

James · Thursday at 10:18 PM

An Buachaillín Bán said:
Thanks for the reply. I tested across.my A1 and A2 and didn't get voltage reading there when pressing start button.

I also thought that it would've been a normally open contact, but as sure as day it was a NO contactor that I removed. Exact replacement.

But you have put a n/c contactor in. (1 contact only)

westward10 · Thursday at 10:26 PM

You need to check the control circuit, is the stop button showing closed?

An Buachaillín Bán · Thursday at 10:30 PM

James said:
But you have put a n/c contactor in. (1 contact only)

My apologies, meant to say it was 100% a NC one I removed.

An Buachaillín Bán · Thursday at 10:33 PM

westward10 said:
You need to check the control circuit, is the stop button showing closed?

Thanks for the reply.

Yes, I had tested both buttons. Start was open until I pressed it, and contacts closed. I proved this through a continuity test.
Stop button was showing closed yes.

westward10 · Thursday at 10:37 PM

This is single phase?

westward10 · Thursday at 10:48 PM

21 and 22 is NC that wouldn't normally be the case for DOL control. Are you sure someone else hasn't fiddled with it.
What would happen if it is NC instead of NO it would be permanently on but you say there is nothing in 21.

An Buachaillín Bán · Thursday at 11:03 PM

westward10 said:
This is single phase?

It is.

An Buachaillín Bán · Thursday at 11:08 PM

westward10 said:
21 and 22 is NC that wouldn't normally be the case for DOL control. Are you sure someone else hasn't fiddled with it.
What would happen if it is NC instead of NO it would be permanently on but you say there is nothing in 21.

Yes that's right, nothing in 21. I'll add that there was a second heavy duty mixer/blender right next to this one, which is working fine. So I decided to open it up to check if contactor was NC also, but it wasn't! That's why I'm so confused.

I asked the chef if anyone had been in to repair it. And he categorically stated no. I asked the head of facilitates also, and he didn't organise for anyone else to call in. The had a temporary power cut one day about 2 weeks ago, and the blender never worked after that.

westward10 · Friday at 8:13 AM

I assume the other contactor has terminals 13 and 14 for the auxiliary which would be NO. If the machines are identical including the starter someone has almost certainly messed with it so either suggest you match the contactor from the other machine and copy how it was wired or switch the contactor to try it in the non working machine to test it.

snowhead · Friday at 8:41 AM

If it's a commercial mixer there will almost certainly be a safety interlock on the head, if it hinges or on the bowl guard if there is one.
The interlock will be in the control circuit for the contactor.
What you shouldn't be able to do is get your hands / fingers anywhere near any moving parts when it's running.

An Buachaillín Bán · Friday at 2:21 PM

westward10 said:
I assume the other contactor has terminals 13 and 14 for the auxiliary which would be NO. If the machines are identical including the starter someone has almost certainly messed with it so either suggest you match the contactor from the other machine and copy how it was wired or switch the contactor to try it in the non working machine to test it.

Yes I just checked the auxiliary terminals and they are 13 and 14, NO. Machines arent identical but this 2nd one has a stop and start button. I'm going to try a NO contactor and will let you all know how it goes.

An Buachaillín Bán · Friday at 3:27 PM

snowhead said:
If it's a commercial mixer there will almost certainly be a safety interlock on the head, if it hinges or on the bowl guard if there is one.
The interlock will be in the control circuit for the contactor.
What you shouldn't be able to do is get your hands / fingers anywhere near any moving parts when it's running.

Ok, sorry if I'm confusing matters.

I'm getting 152v across 1L1 to 2T1,
1L1 to 4T2 and 1L1 to 6T3.

Should I not be getting voltage across the respective contacts, ie 1L1 to T1, 3L2 to T2, L3 to T3?