3 pole contactor trouble. 230 v coil, 50hz. ADVICE PLEASE

[wade88]

Hi guys,

Havnig a small drama here at work trying to re-wire a contactor for a three phase motor. The chap that installed the contactor was firstly NOT an electrician, he was in fact a metal worker....and the job he did certainly worked, but was a little unusual to say the least.

However...i had to take the whole bugger appart because i wanted to clean the contacts as some arcing was occuring and the contactor was failing to open and close causing some rather awkward moments when the motor stopped running consequently causing the mixer to stop working.

And so i have wired the contactor back together, the way it was done initially, and now the MCB wont stay in and i have several *pops* sounding from the isolator switch, the control switch for the motor and the breaker itself...NOT ideal.

I apologise for the epic post here, but just want to set the story straight so im sounding clear. The incoming power is 3 line and earth SY and what looks to be 2.5mm, this has been coupled in with the motor power which is also 2.5mm SY 3 Line and E into the L1,L2 and L3 terminals. the motor control switch (also 2.5mm SY 3L+E) has been terminated into the T1,T2 and T3 ports. But the chap has wired in a strapper from L2 to a port labelled "13" which i belive is the coil power? And there is another strapper going from A2 on the south side of the contactor and i believe that was terminated into one of the "T" ports. So i terminated it into T3 for the sake of argument as the piece of cable was only long enough to be terminated here and everything just went Bang and that was that.

This contactor also has a thermal cut out attachment on it.

Confused. Help. Please

 

[RogertheBodger]

Hi Wade, Difficult to tell what you have there from your description, The supply conductors should go into L1,L2,L3. and the supply to the motor should go into T1,T2,T3. you say you have 3 other conductors and a 230v coil?
What is the motor control switch? just turns the motor on and off?

 

[wade88]

Hi Rodger

Yea excuse my rather fluffy description, its that time of day it would seem!

Yes the motor has been wired to an on and off switch and also a no volt safety switch that has been installed to stop people from lifint ght ecage on the mixer and putting their arms and legs in when its still turning!

So the contactor has been wired as thus;

Main power in- L1,L2,L3
Motor power - L1,L2,L3
Motor switch/no volt safety switch - T1,T2,T3

But the Earth from the motor control switch has been labelled as a live conductor and has been terminated into the "A1" port.

 

[Jurasic Spark]

Are you sure it is not a 400v coil as a 230v would require a N? L1, L2 & L3 feeding the main N/O contacts and the opposite side of these 3 contacts go to the motor. If it is a 400v coil then one of the feeds in links round to 1 side of the coil and the other side of the coil goes throuhgh the auxiliary o/l contact, the stop button and the start button and then to another 1 of the feeds. The start button will have a hold on contact in parallel with it.

 

[benji]

well i think 13 is one side of a aux.contact i also think you should google d.o.l. starter and you should find a wiring diagram

 

[RogertheBodger]

From what you say it sounds like you have 400v across your motor control switch, the marked earth wire could be the neutral for your coil, the 3 conductors connected to L1,L2,L3. going to your switch should be disconnected from L1,L2,L3. I don't know what kind of switching arrangement you have, what you should have, simply put, is 1 live from a phase (L1) going to your switch, from the other side of your switch to the coil A1 and then from the other side of the coil A2 to a neutral and complete the circuit. sounds also like you have an interlock for the bar you mentioned but where the other two conductors go I can't visualize.

 

[Jurasic Spark]

Diagram 400v coil. If you have a 230v coil then feed one side of the coil throught the control circuit as shown and the other side of the coil connects to your Neutral

 

[Knobhead]

I was just going to do a drawing for him but you beat me to it!

 

[wade88]

Thanks for the help chaps, but your going to have to dumb it down a bit for me...Newbie...and trying to read circuit diagrams at the moment is about as easy as reading brail for me so appreciate the thought Jurrassic but out of my league at the moment haha.

The coil is 400v yes, my bad, it just occured to me its being fed by a 3 pole breaker so therefore it must be three phase. what a plum.

And so here it was i have. Power in - terminated at l1, l2, l3, motor power - also terminated at l1,l2,l3 and then another SY 3 core and E labelled control with a 4 pin commando plugged into the switch for the motor, terminated at t1,t2,t3. there is a strap wire terminated in A2 but im sure when to terminate this. and then from the "control" SY cable the earth has been sleeved as live and terminated in the A1 port. this configuaration, caused everything to go pop. and the breaker wont stay in.

 

[johnboy6083]

undo it all mate and start from scratch. use the drawing above to help you. DOL starters aint hard to figure out, and if you follow the drawing it will click.

 

[wade88]

Yea i decided to start from scratch and did some fault finding and after testing the control switch discovered that the switch was actually burnt out...thus throwing the breaker everytime i tried to energise the motor. So, lesson learnt, before faffing for ages trying to make something work that already works...explore all other possible options!

Thanks for the help lads!

 

[wade88]

Sorry i keep aying control switch i mean the DOL. plank!

 

[Knobhead]

You could use the a bit of the plank to wedge the contactor in.
Sorry
BTW it wont be the first time a bit of wood has been used to wedge a contactor in

 

[wade88]

haha doesnt that defeat the purpose of a contactor though once you have "wedged" it in?!

However, tip duely noted

 

[Knobhead]

You get a plant that’s costs £20K an hour shut down it’s surprising what you’ll do