3 phase contactor

[rorie]

Following advice on a different post, i now have a Clarke 3 phase converter, and a contractor from Screwfix to run my 3phase motors.

The converter provides a 4 pin socket (3 phase and earth) and my motors all have 3 phase and earth.

But my contractor has the wiring diagram below, suggesting i need a neutral as part of the 'hold on' circuit?

The text at the top says
230/240v col, phase to neutral
400/415v coil, phase to phase

But the wiring diagram is the same!

So, in idiots words, what to i do?

 

[MattH]

Which coil have you bought, 230v or 415v?

 

[WorkshopChris]

Providing your coil is 415v then you connect between any 2 phases. Transwave converters normally work best with the coil operation between L1 & L3.
So in the diagram above the N terminal becomes L3.
http://www.powercapacitors.co.uk/wp-content/uploads/2013/10/MT-OI.pdf

 

[rorie]

ah, and here we have the problem then - the contractor is a 240v coil!

I have a normal 13 amp socket feeding 240v to the converter. Can i just tap into the neutral (probably inside the converter if i can) and use that as my control for the coil?

 

[WorkshopChris]

Have a look and see if the converter has a neutral connected to the front socket if so you should be able to take a N & L1 feed.

 

[MattH]

Just a thought, return the 230v contactor and get a 415v unit.

 

[rorie]

Not sure i understand what you mean about a neutral to the front socket? Its a 4 pin socket on the front - 3 live and earth.

MattH - yes, that would have made my life easier, but had these contactors for a while now and can't return them

 

[MattH]

But... The only way to do this properly is to use the correct starter. Using the 230V Single phase incomer to the converter is a bodge at best.

For £30 just grab one of these rated to suit your motor (this will give you overload protection as well which the one you have doesn't):
http://www.ebay.co.uk/itm/DOL-3-Pha...hash=item3f203ddcea:m:moRb6uhQ0kSq1n_-hy4_fHg

 

[rorie]

Why would it be a bodge job? Surly all the unit needs is a 240v neutral feed... then L1 is 450V as per the wiring diagram?

 

[WorkshopChris]

Not sure i understand what you mean about a neutral to the front socket? Its a 4 pin socket on the front - 3 live and earth.

Ok some have 4 some 5 pin all depends on the model and spec.

In that case just run the 3 phase straight in and out and put all the control wiring on a 13a plug with a 3a fuse.

 

[rorie]

Ok some have 4 some 5 pin all depends on the model and spec.

In that case just run the 3 phase straight in and out and put all the control wiring on a 13a plug with a 3a fuse.

So L1 shouldn't be the control live (given its 450v)?

 

[MattH]

Why would it be a bodge job? Surly all the unit needs is a 240v neutral feed... then L1 is 450V as per the wiring diagram?

Mixing pre-converter single phase and post-converter 3 phase within the same contactor. Ignore me I'm sure it's green book all the way.

 

[rorie]

I'm just trying to understand the best way to use what i currently have given the wiring diagram seems to suggest i use L1 and neural....

So i should take live feed and neutral from a 3 phase socket as suggested above?

 

[WorkshopChris]

So L1 shouldn't be the control live (given its 450v)?

i would not introduce a neutral from outside of the converter, if its not on the front panel outlet.
Either a separate control circuit or a get a 415v coil.

 

[MattH]

i would not introduce a neutral from outside of the converter, if its not on the front panel outlet.
Either a separate control circuit or a get a 415v coil.

This.

 

[brightspark]

Have a look and see if the converter has a neutral connected to the front socket if so you should be able to take a N & L1 feed.[/QUOTE it should have a neutral on the output socket and as u say if it has 240v coil connect to l1 and n

 

[brightspark]

I'm just trying to understand the best way to use what i currently have given the wiring diagram seems to suggest i use L1 and neural....

So i should take live feed and neutral from a 3 phase socket as suggested above?

from the output 3phase socket yes

 

[Turbo]

I don't think it would be wise to take your neutral from your single phase feed, it would need to be from the output of your converter. To get 240v from a 3 phase supply you connect between any one of the 3 phases & the neutral.

If there is no neutral your best bet would be to change the coil in the contactor to a 415v one, should work out cheaper than buying a complete contactor.

 

[henry Kadzielski]

Good morning gents.
All contactors have replaceable coils. With the contactor number go to your electrical wholesaler who can provide you with a 415v (not 450v) version. Don't mix pre and post convertor voltages

 

[rorie]

Ok, so i managed to return the contactor with 240v control, so i purchased one with a 440v control and installed i tonight. All works well!

My two motors are 1/2 horse power (i'll only be running one at a time). I need to get an extension cable to hook up my converter to the machines, but the pre-made extension cables are pretty expensive. As i am pulling such small loads, i am wondering if i could just make up a cable myself using flex. Would 2.5mm flex be sufficient? Or could i get away with smaller?!