2 post ramp wiring 3 phase to single phase

[gaz-c]

hi, i am in need of some advice on wiring for a 2 post ramp, the ramp is a Bradbury electro mechanical that was 3 phase i have replaced the motor with a 3kw single phase capacitor start capacitor run motor, what i need to know is can i run the motor from the original drum switch and contactors, if so is it a easy set up, i cant post pictures at the moment due to not having enough posts, thanks in advance, Gaz.

 

[Deleted member 26818]

If you are using the original 3phase contactor, then you would need to link the single phase across all the 3 phases, otherwise the contactor will not pull in correctly.
Connect your feed to the first terminal, link out to the second and on to the third.
Do the same on the out going side.
Failing that, replace the 3phase contactor with a single phase item.
The rotary switch is fine to be used on single phase.

 

[Darkwood]

Why wont the contactor pull in properly Spin?
Your methods are only needed if an overload is fitted as some require a balanced load across all three lines and motor overload protection could be provided before the contactor in some cases, although it wont do any harm looping single phase through all lines.

 

[telectrix]

also check the coil voltage of the contactor. if it's 415V, it will need replacing for one with a 240V coil.

 

[Darkwood]

Think this really is a case of 'we need to see the wiring plan' as it could be a simple change over or a complicated (if you not up on controls) rewiring of the control system and changing of the control gear, i would have looked at alternative options before replacing the motor personally.

 

[Bobster]

Have you got a neutral?

 

[pottymotty]

More info is required about the ramps method of up and down . Is it hydraulic or pulley and wire .did the motor run opposite direction to take it down or was it by gravity .single phase motors can be wired for forward and reverse .bit more complex than 3 phase but can be done .as a single phase motor would generally have to be much bigger and greedier on amps to give the same starting totque i would recommend altrring the pulley ratio to increase torque and keep the motor size sensible the knock on effect is a slower up speed but its rarely important whether it takes half a minute longer to lift

 

[gaz-c]

also check the coil voltage of the contactor. if it's 415V, it will need replacing for one with a 240V coil.

hi i will upload a picture of the info on the contactor tomorrow.

 

[gaz-c]

Think this really is a case of 'we need to see the wiring plan' as it could be a simple change over or a complicated (if you not up on controls) rewiring of the control system and changing of the control gear, i would have looked at alternative options before replacing the motor personally.

i have a copy of the original schematics i can scan and upload tomorrow, the reason for going single phase motor was the cost of the inverter £400-£600 and nor guarantee it would work properly

 

[gaz-c]

More info is required about the ramps method of up and down . Is it hydraulic or pulley and wire .did the motor run opposite direction to take it down or was it by gravity .single phase motors can be wired for forward and reverse .bit more complex than 3 phase but can be done .as a single phase motor would generally have to be much bigger and greedier on amps to give the same starting totque i would recommend altrring the pulley ratio to increase torque and keep the motor size sensible the knock on effect is a slower up speed but its rarely important whether it takes half a minute longer to lift

hi the ramp is a electro mechanical twin screw type with the chain running across the bottom the motor needs to run in both directions to raise it up and down, the motor came with basic wiring diagram.

 

[SAILOR48]

If as you say it is a electro mechanical it may be gravity down, or driven if it is driven it will need to be reversed.
Also take into consideration the extra starting loads when starting with the load off of the floor( IE some way up) If you have changed a 3 hp 3 phase for a single of the same size, this could be a problem.
I have known this to happen particularly when the lift is worn.
The supply cable, protection device( if MCB be changed to a single phase) and isolator, should be checked to ensure they are of sufficient sizes.
The pulley idea is OK you will have to change the belts so you can get the tension right.
Above all don’t get the direction wrong when you first start it, if the arms are on the ground it will unscrew and mess the lift right up.
Always press the down to try it can only go up if wrong.
Another common happening is that when these lifts are moved the chain has to be re tensioned
There is a switch underneath that detects loose or broken chain

 

[gaz-c]

here is the wiring diagram and the picture i hope you can make some sense of them, thanks.

 

[Darkwood]

Its a 400v coil on the contactors, you will need to source either a replacement coil for existing contactors or replace the full contactor assembly on all contactors/relays as i said before there were other methods available to adapt a 400 volt motor to single phase and i would have thought they may have been cheaper in the long run.

 

[Knobhead]

You can use the drum switch but it's not a simple matter. The overloads will need uprating and rewiring.

 

[vaughant]

Its a 400v coil on the contactors, you will need to source either a replacement coil for existing contactors or replace the full contactor assembly on all contactors/relays as i said before there were other methods available to adapt a 400 volt motor to single phase and i would have thought they may have been cheaper in the long run.

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!!!!

 

[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.

 

[paulr57]

Sorry, Navy didn't do apprenticeships or issue little red bibles. I'll try Antiques Roadshow.

How about getting back to the point?

 

[Deleted member 26818]

I seem to remember something given away by a company called Brook Compton.

 

[Knobhead]

That's the one. Mines within arms reach at the moment. It's getting a bit like me though, a bit frayed at the edges.

 

[gaz-c]

hi all, sorry for lack of updates, with a house move and lack of time things had to put on the back burner, i haven really got any where yet with this, what would be the best way to get this working can the original drum switch still be used but with new contactors?, i have seen this on ebay but i would be concerned about how it would handle the load and the fact it can be used with limit switches, any help would be much appreciated, thanks. ROTARY SWITCH SPRING RETURN TO OFF CAR LIFT REVERSER CHURCHILL UP DOWN RAMP 20A | eBay

 

[gaz-c]

anyone?

 

[Knobhead]

Who are you?

 

[gaz-c]

Who are you?

Tony i understand what you asking, im just not sure what you are getting at? i am only asking for advice, if i have offended yourself or anyone else please feel free to let me know.