contactor/overload

[mackos]

Hi is it poss to get single phase all in one contactor/overload for small induction motors 1-2 Kw.We have lots of small motors for swimming pools & they all have 3 phase contactors with the overload slung underneath most of them 40 amp which seems a bit overkill.any suggestions anyone.Thanks Mack.

 

[thepurple1]

A simple answer to your question is no

 

[pmac10]

you can get 3 phase all in ones, your set up sounds well strange, wanna elaborate?? maybe i could point you in the right direction

 

[lewlec]

Hi

what is actually controlling these contactors? Are they d.o.l with start stop on the front? If so is that what you are looking for? Or are you looking for stand alone overload?

Regards
gary

 

[mackos]

Hi the contactor is controlled by a time switch to bring the pump on at various times in the day.all these pumps are under 2 kw drawing 4-8 amps.I just thought that a 40 amp 3 phase contactor & 3 phase overload screwed underneath was a bit much,that's why I wondered if there was a smaller & cheaper all in one alternative.thanks Mack.

 

[lewlec]

Hi there

you will need a contactor and overload for the way they are being controlled and they are available in single phase, maybe it is possible for you to use the existing contactors and just change the overload to the appropriate rating. Also two of the poles will need to wired in series for single phase to balance the overload. Hope this is of use to you.

Regards
gary

 

[mackos]

Thanks for the reply.The main reason I was asking about a smaller all in one version is I am coming back to England in a couple of weeks & could stock up on said item if it was available I know it isn't out here.I think I've read your post before about wiring up two of the contacts in series before i'm sure the theory is sound but I must have looked at 50 of these pumps & all have been wired singularly L & N with the NC contacts on the overload going through the auto/manual switch.Haven't had a problem with them tripping YET.thanks again Mack.

 

[johnboy6083]

i used to wire plantrooms for water feautres and irrigation systems, and i was taught to loop the live through the contacts to balance the overloadas gary has said. As per the configuration, we used to use ABB thermal magnetic overloads, and the contactor would either be bolted underneath, or wired after the overload. The motor starters can be bought in a variety of loadings.

 

[sappaazz]

do we have single phase overloads now...??

 

[Marvo]

The thermal overloads that attach to the contactor are for 3-phase but as already stated they can be wired with the live looped through them if it's a single phase motor. The 40A contactor and overload is a tad on the large side for a single phase pump that's <1kW. You could use the contactor although it's unnecessarily expensive but the overload will be useless.

Very small motors can be protected with a small thermal breaker like this one which would usually be installed in the motor terminal box.


These things trip in < 30secs at a current 150% of their rated value.

Alternatively you could just sourcea lower value thermal overload that fits the contactor, they're generally available down to 0.2 amps for standard contactors.

 

[sappaazz]

thanks marvo

 

[Engineer54]

Do as has been suggested, looping the contacts! The contactor size (Amps) is just the max current that the contacts can safely carry. The overload unit however, should always be sized to the motor it's controlling, these modules can be very easily interchanged. I'm sure we don't need to tell you what overload size and setting to use for these 1 to 2 KW motors!! lol!!

Most swimming pool filtration pumps of pools between 7 X 3m to 10 X 4m will have a pump of between 1.5 to 2HP...

 

[Darkwood]

Ruddy nora ... this is raiding the archives -july 2010..... might have been better started as a new thread, think if threads dont have sticky then should have an expiry date possibly one yr.... ive recently twice had ppl suggesting alternative solution on posts from yrs ago where the replies were relevent for the time of print but differ now.

 

[Engineer54]

I didn't notice either!! lol!!

 

[Marvo]

I noticed but with him being a fellow African I didn't make a big deal of it Sometimes Google searches on a subject will throw up old threads but if it's a relevant question it's fine if they get added to much later.

 

[Robotstar5]

Ruddy nora ... this is raiding the archives -july 2010..... might have been better started as a new thread, think if threads dont have sticky then should have an expiry date possibly one yr.... ive recently twice had ppl suggesting alternative solution on posts from yrs ago where the replies were relevent for the time of print but differ now.

One forum I use locks the threads when they reach a certain age, allows the info to be searchable but not "resurrected"

 

[Darkwood]

One forum I use locks the threads when they reach a certain age, allows the info to be searchable but not "resurrected"

I only put that because i was recently quoted about under unit lighting and was suggested led would be better than my suggestion.... i replied that had they been available at the time of post 4yrs ago im pretty sure that would of also been my recommendation.... its not a issue really most of the time but when advice starts to span different editions of the regs then brings 4-5yr old threads up will just get the new sparkies all dizzy.

 

[Marvo]

Yep, I can see with changing regs over the years there could be confusion but the date of every thread is given on the main index page and every post also has the age on it so there shouldn't really be confusion. Lock/don't lock, swings and roundabouts I suppose.

 

[Knobhead]

I'm a member of a few Urbex sites. They all lock threads after 6 months to everyone except the OP. If the OP has new information the thread is reopened to everyone.

 

[Brightspark2]

These thread resurrections are annoying, they should be locked...

I only put that because i was recently quoted about under unit lighting and was suggested led would be better than my suggestion.... i replied that had they been available at the time of post 4yrs ago im pretty sure that would of also been my recommendation....

Ha ha that is funny...