Three Phase Momentary Switch

[><(((º>]

Hello all,
I'm looking for a 3 phase momentary switch to operate a hydraulic lift, basically I want a green button to press to run and it stops when I let go. They are easy enough to find for single phase but not 3 phase. Because they don't seem to be available I'm getting the idea that I'm not searching for the right thing. Any pointers would be a great help Thanks

 

[pete01]

Make the green button activate a contactor?

 

[Highway Man]

You would want a stop button too in case of failure of the start switch or of the contactor.

 

[morqthana]

How come this lift didn't come with all the controls it needs?

 

[jj4091]

What is the electrical loading of the hydraulic pump ( how many amps does it draw ). Do you need it to go up and down or just up.

 

[Highway Man]

How does it know when to stop? Does it have limit switches so that it knows when it has reached its height or ground will it rely on you taking your finger off the button? It all sounds a bit in the air and not quite right as you have described it. More info is definately required as there could be some serious dangers you may have overlooked.

 

[><(((º>]

Sorry if I wasn't clear enough. The current situation is that there is a start button and a stop button. When you press start it runs (Raising the lift) until you press stop. There may be limit switches, but I am always careful to switch off before it gets too high. Lowering is achieved by manually opening a valve. I want the lift to stop when the go button is released rather than press the stop button. (It could be an additional button, which would mean press 1 button and hold a second button)

 

[pete01]

You can probably remove a link on the starter, I've done it before for roller shutter doors.

Dont think I'd mess with a lift control system though.

 

[Highway Man]

Sorry if I wasn't clear enough. The current situation is that there is a start button and a stop button. When you press start it runs (Raising the lift) until you press stop. There may be limit switches, but I am always careful to switch off before it gets too high. Lowering is achieved by manually opening a valve. I want the lift to stop when the go button is released rather than press the stop button. (It could be an additional button, which would mean press 1 button and hold a second button)

OK that all sounds to be good, I took it you were relying on taking your finger off the start button to stop it. So you need a latching circuit where one press of the start button starts and runs the lift until you stop it by the means of the stop button, give us the ratings of the pump and I will point you to the control you need.

 

[Highway Man]

You can probably remove a link on the starter, I've done it before for roller shutter doors.

Dont think I'd mess with a lift control system though.

I have had to sort out lots of rapid and rollerr doors out in my time, a real pain when they skip the limit switches. Most now are all pcb controllers where the pure electrical circuits with relays were the best ones to fudge

 

[><(((º>]

OK that all sounds to be good, I took it you were relying on taking your finger off the start button to stop it. So you need a latching circuit where one press of the start button starts and runs the lift until you stop it by the means of the stop button, give us the ratings of the pump and I will point you to the control you need.

Yes, I want taking my finger off the start button to stop it, a dead man switch. It already runs until I press the stop button

 

[trojanhawrs]

Yes, I want taking my finger off the start button to stop it, a dead man switch. It already runs until I press the stop button

Likely it's through a contactor and you have a hold on contact keeping the motor energised until broken with the stop. You can rewire it without the hold on contact.

 

[Highway Man]

Likely it's through a contactor and you have a hold on contact keeping the motor energised until broken with the stop. You can rewire it without the hold on contact.

Whats the benefit to that?

 

[trojanhawrs]

Whats the benefit to that?

It makes it a "momentary" switch. Easier to inch the lift

 

[333rocky333]

Your existing green button is likely a 2 contact momentory switch or manually pushing on the starter contacter, same used whether single or 3 phase.
As above its the hold in contacts that are latching the contacter, bypassing them will change the start button to a jog button