stop start

AlexGoode · May 9, 2014

As an apprentice, I was learning the other week about stop start wiring through a contactor, can someone please help as basic as possible so I can have a good understanding of it. cheers

davesparks · May 9, 2014

What do you want to know?

AlexGoode · May 9, 2014

Just general wiring and why each cable goes to each terminal number

Darkwood · May 9, 2014

A diagram is the best way to visualise things...

One side of the contactors coil is usually permanently connected and the other side goes through the control circuit first, stop buttons have priority and over any start commands so when you take a supply to the retaining contact it comes of the control circuit after any stop buttons or overloads etc and usually is taken from the input side of the start button.

The output side of the start button goes direct to the coil so pulling the contactor in when you press the button, this would drop back out when you let go so you have a retaining contact that pulls in at same time and the output of this retaining contact also goes to the coil with the startt button output.

Now once the retaining contact is in it is as discussed energised from the control circuit at a point passed all stop commands so pressing any stop button will loose the power through the retaining contact to the coil dropping the contact out.

SirKit Breaker · May 9, 2014

AlexGoode said:
As an apprentice, I was learning the other week about stop start wiring through a contactor, can someone please help as basic as possible so I can have a good understanding of it. cheers

PM me with your email, and i will send you a wiring diagram and explanation. I have problems trying to post stuff like this on here.

Cheers..............Howard

Richard Burns · May 9, 2014

This is a picture I found I had showing a method of switching a contactor as a stop start.
Looking at it, it does not seem to be a very good way of wiring the circuit but it does demonstrate the principle explained by Darkwood above.

This is intended to switch on and latch on a contactor via a start button, this then operates another contactor to operate a 3 phase heater.

Just realised why the circuit looks odd, I drew it!

Marvo · May 9, 2014

I'm not sure why you wouldn't just use a single contactor with a normally open auxiliary contact. Also a mixture of permanent supply and switched supply on the load side of the left hand contactor is a bit unorthodox.

Darkwood · May 9, 2014

question for the OP to think about ..... what is the problem of having the start button before the stop as priority ... how can you check this is not the case on a control panel by pressing the buttons?

Richard Burns · May 9, 2014

Marvo said:
I'm not sure why you wouldn't just use a single contactor with a normally open auxiliary contact. Also a mixture of permanent supply and switched supply on the load side of the left hand contactor is a bit unorthodox.

True..

Richard Burns · May 9, 2014

Is this better and clearer?

Darkwood · May 10, 2014

Richard Burns said:
Is this better and clearer?
View attachment 24638

Now all you need is to stop using switch symbols and use push botton symbols

...:thinking: soz Rich just been annoyingly picky 'whistle~~~~'

Darkwood · May 10, 2014

Richard Burns · May 10, 2014

OK now what can I pick holes in on your diagram?:thinking:
Hmm... yeah OK not bad!
The OP did not say it was for a motor though! (I think I am clutching at straws here)

Knobhead · May 10, 2014

Darkwood · May 10, 2014

Richard Burns said:
OK now what can I pick holes in on your diagram?:thinking:
Hmm... yeah OK not bad!
The OP did not say it was for a motor though! (I think I am clutching at straws here)

I ripped mine off google images so was cheating a little, so far I get 0/10 for effort giving you the winning hand back.

Arrh! Tony's arrived with his famous library of wiring diagrams ....was starting to worry for a minute!