Wiring a 240v motor to a push button on/off switch?

[Harddisk25]

Hi, I've got a 1950's motor that i would like to wire to a push button on/off switch.

Is the a push button switch on the market to do what i want in the diagram or a way of wiring one as i can not find any on ebay? The only ones i can find that is a close match is the 3 phase switches like this one (ebay No. 290930766073).

 

[Marvo]

What type of motor is it? What size motor? Why not just use a DOL starter and you're protecting the motor as well that way?

 

[Harddisk25]

I thought about using a dol starter but they to big and cost to much. The motor is a 1/4hp

 

[Marvo]

Yeah, 1/4 HP is very small, the DOL starter would probably cost double what the motor costs.

How are you going to mount the switch? You just need a 5 Amp, 230v 2-pole switch. You can use a single button latching switch, press once for on and press again for off.

 

[Pete999]

ffs ???????????????/

 

[Marvo]

Cut him some slack Pete, I'm guessing he's a DIY'er.

 

[Harddisk25]

The motor is mounted on a trolly running a small compressor that runs model engines. The switch will be screwed to the trolly.

 

[Darkwood]

What is the motor doing would it pose a risk if power failed and was re-established causing the motor to start without warning?... if so then you will need a device that will drop out with power loss and stop the motor starting up again on power up without a deliberate action.

Edit ... your last response just answered half my query...but i was writing when you posted.

 

[nickblake]

its relatively easy you can just use an on off switch or you can use a non latching switches with a relay so as your picture what you need is two two way push switches with normally open and normally closed contacts and a relay its not easy to explain how to do it let me have your email and ill do you a diagram should be able to do it for less than £10

 

[Marvo]

So you'll need a switch with it's own enclosure at the back to contain the connections. Have a look at your local electronics shop or Maplins maybe for a small project box and a 2-pole 230v 5 Amp switch that will mount in it. You'll also need a couple of 20mm glands for the cable entries.

 

[nickblake]

Little drawing of circuit for it parts you can get from ebay CPC or maplin

 

[Darkwood]

View attachment 25903Little drawing of circuit for it parts you can get from ebay CPC or maplin

Its functional nick but Electrically poor design, your stop button should have priority over the start not the other way around.

 

[Lucien Nunes]

The other problem with that arrangement is that the start pushbutton will have to make the motor inrush current instead of just the relay coil current and if it is immediately released before the relay has latched, break it as well. Separate contacts should be used for the motor and holding circuit.

But for a compressor I can't see why you would need no-volt release, after all when the pressure switch closes the motor will start by itself anyway. Talking of which, where is the pressure switch?

 

[nickblake]

Your right dark wood my error what happens when you do it in a rush

 

[nickblake]

The other problem with that arrangement is that the start pushbutton will have to make the motor inrush current instead of just the relay coil current and if it is immediately released before the relay has latched, break it as well. Separate contacts should be used for the motor and holding circuit.

But for a compressor I can't see why you would need no-volt release, after all when the pressure switch closes the motor will start by itself anyway. Talking of which, where is the pressure switch?

Sorry incorrect motor is not connected to the switch the supply for that comes through the relay , pressure switch ??? its just an on off switch, the pressure switch would be built into the compressor , no volt release , with this type of switch you have to have a release or youll never switch it off unless you turn the power off , its like any DOL starter once the relay or contactor is energized the power on the out going of the relay is the fed back through the stop switch and overload so if either is operated it switches off the relay or contactor

 

[Lucien Nunes]

motor is not connected to the switch

Oh yes it is! Except for when you are pressing the stop button, the motor and relay coil are in parallel; you can't energise one without the other. The start and stop buttons will carry the motor current until the relay operates. Unless you have special electricity that knows only to flow from left to right!

My point about the pressure switch was this: Any decent manual switch will start a 1/4hp motor, it doesn't specifically need a relay/contactor/starter. The advantage the relay provides is no-volt release, i.e. freedom from unexpected starts. But a compressor motor controlled by a pressure switch starts without warning anyway, largely negating the advantage of the NVR. Therefore, unless the relay is used to relieve the motor load from the pressure switch, there's little point in using one, an ordinary switch will suffice.

And yes, I do realise that one relay can't both latch the buttons and relieve the pressure switch!

 

[aesmith]

Unless I'm missing something, then something like this ought to do the job, and is available ready made. I'm sure other similar are available, this just happens to be the type I use on my router table (where I definitely don't want it restarting when power's restored).
http://www.axminster.co.uk/axminster-light-duty-nvr-switch

 

[Harddisk25]

Thanks aesmith that's what I've been searching for.