Contactor/overload wiring help pls...

[Colin33]

Hi all, never had to wire a domestic sewerage pump before so not my usual line of work. Was told I need a thermal overload for the pump (1.1kw) and this came with a contactor (not sure why it needs a contactor, but it appears that the overload unit need one to plug into. Can anyone please advise on how to wire this? The enclosure has an earth and Neutral link inside.

 

[LankyWill]

Colin where abouts are you? Without sounding rude, we're here to advise not step by step tell you. Any spark should be able to figure out that sort of control panel anyway, they're basic compared to others.

 

[telectrix]

@ OP whereabouts are you? it's not a big job for one of us who may be close to you.

 

[Colin33]

Sorry, don't have a pic of the cover. It has a blue reset button which sits over the contactor. Not sure why, because the thermal overload has it's own reset button.

 

[davesparks]

Something like this...

View attachment 36905

From what the op has said I think the float switch is already connected directly to the pump and doesn't need including in the control circuit of the starter.

 

[Colin33]

Location- West Cornwall...

 

[davesparks]

Couldn't find anyone close by willing/able to do it. I wired it up temporarily so that it could be used and decided to ask for help here. If you don't wish to help Dave then why even reply?

I do wish to help, but if you already have the wiring diagram but can't read it then there's nothing I can do except recommend getting an electrician to do it.

 

[westward10]

From what the op has said I think the float switch is already connected directly to the pump and doesn't need including in the control circuit of the starter.

Ah yes you are probably correct so they are just suggesting the thermal overload and not a contactor.

 

[davesparks]

Ah yes you are probably correct so they are just suggesting the thermal overload and not a contactor.

Yes, I think a motor protection circuit breaker would have been more suitable than a whole DOL starter.

 

[westward10]

Yes, I think a motor protection circuit breaker would have been more suitable than a whole DOL starter.

I am with you on that just wire in and out, easy.

 

[Colin33]

I do wish to help, but if you already have the wiring diagram but can't read it then there's nothing I can do except recommend getting an electrician to do it.

If you knew how to do it then why not just tell me which connections (they're all marked on the unit in the pic) to put the L/N feed into and which connections to put the L/N pump wires into and which (if any) to link together. Thought that's a pretty straight forward request for someone who is familiar with these?

 

[westward10]

If you knew how to do it then why not just tell me which connections (they're all marked on the unit in the pic) to put the L/N feed into and which connections to put the L/N pump wires into and which (if any) to link together. Thought that's a pretty straight forward request for someone who is familiar with these?

You are asking for advice here not sure this is the way to achieve that.

 

[Colin33]

No need for that Dave is quite rightly thinking you may have the wrong device for the job.

Yes I agree, the client had a company come and install the pump but they didn't do the electrics. I asked what's needed to control the pump and they supplied me the gear as in photo. Seems over the top to me, but that's what I have. I see no reason for the contactor, but assumed it's needed just to house the overload because the overload is not din mountable....

 

[davesparks]

If you knew how to do it then why not just tell me which connections (they're all marked on the unit in the pic) to put the L/N feed into and which connections to put the L/N pump wires into and which (if any) to link together. Thought that's a pretty straight forward request for someone who is familiar with these?

To start with I think you have the wrong device for the job.
What you have there can be made to do the job but it seems like an over the top solution.
I can tell you exactly where to put the connections, though a simple diagram has already been posted by someone else.
L and N in to the top of the contactor, L and N out from the bottom of the overload.
The start button needs to be in parallel with the hold in contact
The stop button (if present) and overload terminals 95 and 96 need to be in series with each other and in series with the hold in contact.
You need to loop one of the outgoing connections through the third pole of the contractor and overload to avoid unbalancing the load through it.

I don't know the flc of the motor so cannot tell you where to set the overload trip, you'll have to do that for yourself after reading the data plate.

 

[Andy-1960]

The overload itself will not disconnect the power in the event of an overload, it purely detects, this is why you need the contactor, the normally closed auxiliary contact on the overload will open and de-energise the contactor in the event of an overload.
If this is to be used just to provide a feed to the pump with a prewired float sw, wire it as my diagram above but ignore the float switch, take the live straight to the overload (terminal 95)

 

[davesparks]

Yes I agree, the client had a company come and install the pump but they didn't do the electrics. I asked what's needed to control the pump and they supplied me the gear as in photo. Seems over the top to me, but that's what I have. I see no reason for the contactor, but assumed it's needed just to house the overload because the overload is not din mountable....

It's not just the mounting of the overload that requires the contactor.
An overload trip is just a sensing element, it sends a signal via the contacts 95 and 96 to another device (in your case the contactor) which actually breaks the flow of current to the motor.