2 post ramp wiring 3 phase to single phase

[Knobhead]

Where can you see that?I could be wrong but it looks like its using a single phase to me off terminal 3 on km1?
Probably not much help either way!!!!

Learn to read a drawing. Control is from L1 & L2 = 400V

 

[Deleted member 26818]

I take it, that the rotary switch is used to make the lift go up and down, rather than individual buttons?

 

[Knobhead]

It's a very old set up Spin. To be honest last time I saw one like it I was an apprentice.

 

[snowhead]

Learn to read a drawing. Control is from L1 & L2 = 400V

And the other (obvious) clue, no neutral at the incomer.

 

[vaughant]

Learn to read a drawing. Control is from L1 & L2 = 400V

Learn a new thing every day.
I can see it now but can honestly say I've never seen that type of wiring system before,always with a neutral.

 

[Knobhead]

Learn a new thing every day.
I can see it now but can honestly say I've never seen that type of wiring system before,always with a neutral.

Running a neutral is just a waste. Think, if it was a tidy sized motor would you want to pay for a 25mm 4 core when you can get away with 3 if you use a 400V coil.
That aside, control shouldn't be above 110V realy.

 

[vaughant]

Running a neutral is just a waste. Think, if it was a tidy sized motor would you want to pay for a 25mm 4 core when you can get away with 3 if you use a 400V coil.
That aside, control shouldn't be above 110V realy.

Yeah not disputing it just pointing out its the first time I've ever seen that set up,I had a 2 post lift myself 3 phase & neutral with control @ 240v from memory, a German tecalmit one,great ramp...






Til a mate ripped me off half the money on it!!!

 

[Darkwood]

400v is common in self contained controls (mainly older) where no cables are exported from the control box but re' OPs situe' he has limit switches and as tony has also expressed it really shouldn't be higher than 110v and better still is my prefered choice is 24v D.C. as a large proportion of the control market has this voltage within their products and gives a wider range to pick and choose from.

 

[paulr57]

Oh dear! Looking at your circuit you have two contactors, one for forward and one for reverse. controlled by the drum switch. As direction is changed, third contactor opens and disconnects (stops) the motor until power is reapplied.

This is the reason a 3 phase arrangement has been used, as it is a simple matter to reverse the motor direction merely by changing over 2 phases.

This is not possible with a single phase motor, and woiuld normally require a mechanical reversing arrangement.

 

[Deleted member 26818]

Reversible single phase motors are very common.
Usually have two lives and one neutral.
One live for one direction, the other live for the other direction.
Can be controlled by a three position switch, or by a switch and contactor arrangement
Used on blinds, roller shutters, awnings, etc.

 

[paulr57]

Yes that's absolutely true, but I have never seen single phase reversible motors in industrial power applications such as a ramp. This is why 3 phase is so widespread in industry; efficient power transfer; reduced cable sizes per kilowatt load and motor simplicity and reliability. In this instance, why not just replace/recon the motor?

 

[Knobhead]

Yes that's absolutely true, but I have never seen single phase reversible motors in industrial power applications such as a ramp. This is why 3 phase is so widespread in industry; efficient power transfer; reduced cable sizes per kilowatt load and motor simplicity and reliability. In this instance, why not just replace/recon the motor?

Maybe before you start pontificating on a subject you know little about you should check you facts. Nearly every single phase motor is reversible.

Out of interest how would reconditioning the motor enable it to run on single phase?

 

[paulr57]

Well I must have been working with the wrong motors for 30 years.

My apologies, I thought this site was for grown-ups.

I'll waste my time elsewhere your lordship.

 

[paulr57]

Yes, most of us know that the motor can be reversed by reversing the connections of the start winding if they are accessible which in a lot of industrial units, they are not.

It's a pity that instead of offering advice in a friendly and amicable manner, some people have to land on a crash of thunder to prove everyone wrong!

 

[Knobhead]

If you've been working with motor for 30 years you should have been issued with Brooks "Installation and Maintenance of Electric Motors" it was issued free to all bone-fide industrial apprentices.
The electrician’s little red bible.

Have a look in you’re copy.