Terjem

L1---• •---_| (NO pushbutton to start)
L1---] [---^|---• •---( )---L2 (Relay contact, NC pushbutton to stop, relay coil)

Just Google latching relays. There's plenty to pick from.

Thanks I have tried to google, nearly all answers include two switches one for on and one for off. I only have one spring switch either push to make or push to break. Cheers

Then more switches/pushbuttons are needed. A push-to-break contact is necessary to switch everything off.

Have a look for Telemecanique latching relays. Single button operation.

Are you talking about using the same N/O push button for both latch and release, or separate ones?

Thanks for reply I am looking to use the same switch N/O push to make switch for latching & release Thanks

Don't go there. A circuit that needs power to disconnect itself is just asking for trouble.

Have you purchased the switches?

What type of switches do you have or thinking of purchasing? Can you post pictures or a link to the manufacturers data sheet?

I'm assuming the ones you have or are thinking of purchasing are of the momentary type. Can you purchase a switch that is latching?

Why do you specifically need a pushbutton type switch, wouldn't a standard toggle light switch do the job?

You haven't given us much information to go on.

Yes i have momentary switches. I would like to control contactor with one push i.e push to make then have same switch push again to de activate contactor/supply.

I need this application so lights are not left on, and i dont want switches energised continuous as this is a hazardous area. The switches i have are single pole make break. I do have three wires at each switch.

Is this enough info?

Electrical equipment correctly installed can remain energised permamently in a hazardous area.

In order to achieve the installation as described, a supplementary relays are required.

Why not just use a simple on/off switch instead?

Well you've just taken it to a whole new level, by stating it's a hazardous area. And when you say you don't want the switches energised continously because of this, starts to ring alarm bells. This says to me that the switches aren't suitable for this hazardous area. It's not the steady state condition of these switches you need to worry about. You need to worry when you're changing the state of these switches. When you're making and breaking the contacts, an arc will be produced i.e. a point of possible ignition.

At this point I can't offer anymore advice and, please disregard anything I have previously posted. As it's not appropriate for hazardous areas.

I will say one last thing and, that is the decisions and actions you take from this point forward, could put your life and the life of others in danger. You don't sound as if you have a full appreciation of the area of danger you're heading toward and, the possible consequences. I may be wrong, but please be honest with yourself and, if you don't feel competent enough get somebody in who is, to help you. Be safe.

Define Hazardous Area. If the switch is not EXE approved or marked you have a problem Huston. If it is only IP rated you have a problem Huston.

Where are your contactors being installed. Inside the hazardous area or outside? Your switch will always have a side energised. Any advice you gain here is at your own risk.

If you want helpful advice, offer full details. Adviser beware.

There seems to be some fundamental design concepts missing from the skills catalogue here. To work on circuits for a hazardous area withouth having received and completed appropriate training on the subject might be described as foolhardy or reckless. The forum has been waiting on answers to a number of questions, which have been ignored, suggesting a lack of knowledge or skills with which to consider the implications and determine the correct answer.

So the correct approach is to stop work on the project, and hand over the detailed design to a qualified, experienced Electrical Designer.

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Here's a circuit that will do the job, sorry about the rough sketch but my usual computer is being tweaked, and this one has not got the facilities that I would like.

Basically, first press of the button will energise R2 which will remain latched until you press the button a second time whereupon it will release.

You could do it also with a Mosfet, but that will require voltage reduction etc, this one can use whatever voltage is compatible with the switchgear, and will work on either AC or DC.

The relays will be energised one off, but must be able to hold whilst connected in series.

This should not present a problem as most would fit that criteria. Hope it helps.

Thanks very much i will try that thanks again for keeping it real.

I'm not totally sure as to what your looking to achieve. Is this a domestic or industrial installation.

Take a look at this catalogue from Schneider Electric (other manufacturers will probably have exactly the same kit). I think you need to be looking at something they call an impulse relays. You'll find them in Section 5 starting on page 5/28 (168).

http://www.downloads.schneider-electric.com/sites/oreo/gb/document-detail.page?p_docId=25771917&p_Conf=i#http://www.schneider-electric.co.uk#http://www.schneider-electric.co.uk

Hope this helps.

Very few domestic installations involve electrical equipment in hazardous areas, so one may assume that it is an industrial setting.

It's getting very close to a recommendation that the original poster needs to consult a qualified Electrical Designer locally.

Thanks very much for your help

I will try the catalogue

Please read my Comment #14 above.

I feel you could be heading for a very dangerous conclusion.

Hi Terjem, Finder have a latching relay Type 20.23 C/W 16amp Contact

It is very to use, Pushing the button first latches the relay, the second push unlatches the relay. You could have as many push buttons as you want as long as they are wired in parallel.

The drawing below is only a wiring diagram, the internals of the relay do the job of latching and unlatching.

It also had manual button on the relay, to latch or unlatch.

It is a nice modular unit about the size of a domestic cb.

Thanks thats exactly what i'm looking for

Locking Latching OFF- ON Push ButtonSwitches like this come in all sizes.Push once it's On push again its Off. Get one rated to carry the current of the relay coil.

No good if you want to have multiple push buttons