3 phase contactor advice

[adslev]

http://www.google.co.uk/url?sa=t&so...Y5S4ff4NH5pr4cjgA&sig2=tmfhq_cIxswjcGkDdCeIgw
This is the model of contractor causing me problems


Has anyone had any experience with these schneider dol stop start contractors before.?
Basically I'm trying to supply a three phase motor via a timeclock
This works no problem switching the coil of the contractor however the
start button does not hold the coil in to override the timeclock, you have to manually hold
the button on, also the stop button does not break the coil when the timeclock is running.
It's should be straight forward to do this but I seem to be going round in circles!
More experienced in single phase contractors than these!
Any help or advice would be brilliant

 

[plugsandsparks]

What type of time clock are you using and how is it wired into the start / stop cct ? - I would expect the time clock to give a short pulse if you are going to simulate the start button, wired in parallel to the start button.

 

[Darkwood]

You may have disconnected your retaining contact, i assume the timer puts supply to the coil it pulls in until timing end via a relay on timer, you need to pick your timing to break your retaining link as well as power your coil, also you need to choose a timer that that has resets on power down and have the Stop circuit supply the power to the timeclock.... this may not be as straight forward as you may think.

Really need more info to exactly how you want all this arrangement to work i.e will the start button override the timer function, does the stop reset the timer or does it restart from where it left off, do you need extra controls to initiate timer.... with such little info its hard to guide you.

Or i it is as simple as just using a timer to auto start at a pre set time then you need to 'as plugs has already said' use a pulse signal to the coil then the retaining link will hold it in.

 

[Knobhead]

A pulse time and a latching relay should do.

 

[adslev]

Or i it is as simple as just using a timer to auto start at a pre set time then you need to 'as plugs has already said' use a pulse signal to the coil then the retaining link will hold it in.

Cheers for the replies.
The method above is exactly what I'm trying to achieve.
The Time Clock is switching the coil perfectly bringing it on and off
But the manual stay button will not hold the coil in and the stop button will not break the contact
The schematics provided by schneider have not been helpful.
Can this method be achieved without use of a relay because trying to get a wholesaler open today would be slim

 

[Darkwood]

If you want a time clock to bring the motor on this is a simple task if you want it to also stop it this too is simple all you do is remove the retaining link and the time clock relay becomes the retained supply.

Now if you require manual control as well i.e. a stop, start control then it start to get complicated because you need to list exactly what you want each button to do in each scenario and also what will happen if timeclock is calling for motor run and you wish to somehow cancel it.

You need to ensure the set-up is functional and safe to boot - i.e. that the Stop button has priority and that the motor won't re-energise if the timeclock is still calling when you let go of stop.


The usual simple solution is to have a selection switch that chooses your command options (Manual/Auto) but dependent on safety assessment you may need to have a E-stop system that will give a means to over-ride the time-clock.
Choosing the correct timeclock is key which has a cancel function ...personally id fit a PLC and write the software using a POT' to set delay on time and another POT' to select duration of timer, these can all be overridden or cancelled in the manor you choose.

 

[D Skelton]

Anything wrong with using a two channel time clock?? One channel pulsing start, the other pulsing stop? Seems by far the simplest solution to me given the OPs scenario. This may or may not be the safest method however (little disclaimer there).

If this solution is unsuitable then I'm with DW, a PLC would be ideal.

 

[Knobhead]

Have a look at this. Two chanel pulsed O/P Standard DIN 23162 2 Channel Weekly Timer with Key & Pulse Programming

Set channel one as normaly closed with pulsed open for the stop
Channel two as N/O with plused close for start

The override P/B's can easily be wired in.

PLC? Why?

 

[D Skelton]

Just remember to wire the stop and the n/c contact on the timer in series!

As for the PLC, we have no idea of this motor's application. It may need to be safer than just a timer turning it on and turning it off? Also, far more choice of override settings, what happens if the human needs priority over the machine? What if the machines task for the day has been manually controlled and therefore needs no more operation for that day but the timer is set to operate it anyway? Sure you could use further switches and relays but it might work out more cost effecive to sling a cheap PLC in.

 

[Darkwood]

Have a look at this. Two chanel pulsed O/P Standard DIN 23162 2 Channel Weekly Timer with Key & Pulse Programming

Set channel one as normaly closed with pulsed open for the stop
Channel two as N/O with plused close for start

The override P/B's can easily be wired in.

PLC? Why?

PLC- Because its a lot cheaper, more versatile and easier - simpler to set up by the user, we don't know what this motor is doing at all but having it auto start would probably require a risk assessment and additional control options and/or warning set-up if not E-stop interlock to ensure access to the motor etc operates the E-stop (which again we don't know if it has one).

Although for the OP your link is the simplest form to achieve the basics of what he wants (and the fact i couldn't find this timer when i looked ) i would be very cautious to simply installing it i can't see this would comply unless the set-up is such that auto starting of the motor is not a safety issue for both user and maintenance.

 

[Knobhead]

We’re in the usual situation. Not enough information.

Unless the OP gives some details we may as well give up.

 

[adslev]

Sorry for not updating this yet. Haven't got the chance to get back to it yet.
The motor is to turn an auger for a feeder in a piggery. Their is also a hopper to incorporated into this system
which will has a sensor on it acting as an emergency stop.
Not sure whether or not I want to get involved in this as it is a little out of my comfort zone.
I appreciate all the advice

 

[D Skelton]

Simple answer to your predicament then...

PLC it is

 

[Knobhead]

I still can't see why you're insisting on a PLC. It's a basic circuit.

 

[D Skelton]

For less than the cost of a two channel timer and a couple of relays for the safety circuits you could get a cheap 'n cheerful PLC, especially if you want to be able to manually override the circuit without compromising safety. As soon as you start incorporating numurous timers, relays, sensors and safety circuits is it not just easier to use a PLC?

 

[Darkwood]

Now we know a little bit more got to agree can be achieved with simple control circuit but still have lack of info as to how exactly the Hopper set up will work ie... auto-fill, level sensors etc and as the OP is a little out of his area i not sure he will be able to provide all the info we would require.

My advice is get a competent person in knowledge in these set-ups and also fluent in BS7671 - specifically section 705.