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Wiring diagram to run a motor both ways

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alan_a_kane

New Member
Hi all,

I am new to this site, it looks very good. I am also new to AC motors, hence this post.

I have a 2.5 ton car lift which I want to put in my workshop at home. This was run originally by a 3 Phase motor, which I dont have. I also dont have a 3 phase supply at home.

I do have a single phase 17 Amp motor, 2.6 Kw I think. This has 2 capacitors so it will run in either direction. The plate on it says that to reverse direction you should change 2 wires labelled T5 and T8. I gave it a supply with these wire connected either way and it works fine.

I also have a selection of 10 amp contacts with push button switches, both normally open and closed. Also 2, 4 pole, normally open, 40 amp contactors with 230v coils.

As I see this, if I use 1 contactor for each direction and wire the contactors to switch from the 10Amp contacts, it should be ok. I am in Ireland and we have a 230v supply.

Can anyone suggest a wiring diagram for this?

Thanks in advance.

Alan.
 

Optikon

New Member
SOunds like you understand how you need the wires & relays to be connected.. You should be all set or are you not sure how to wire relays so you can say flip a switch and it runs one way and flip it the other way and it goes in reverse? Try working out a schematic and post it and we'll make sure it works as you like.
 

Dougal

New Member
Hi Andy,
Why dont you just make yourself a 3 phase converter! It's so easy, and you'll have it there in the workshop to run any other cheap 3 phase machines you come across. This is what I did, I made a 10hp one and it runs a 7hp panel saw and a 5hp spindle moulder.. You'll pick up those old 3 phase motor's in Creameries and places like that..If thats what you wanna do, let me know and I'll tell you how I built mine.
I'm in Rep of Ireland too....
 

Sebi

Active Member
Hi, Dougal

i'm interested Your 3phase converter, i hope, not contains a processor...(i'm not familiar with proc.)
 

Dougal

New Member
Hi Sebi!
It's really quite simple, and though not really suitalble for running high end CNC machines, it will run other 3 phase motors perfectly.

The thing is, a 3 phase motor will RUN on single phase, but will not start
with single phase alone. Put simply, what happens in mine is, because the motor is one of the old heavy types (not new aluminium frame) and because of it's size (10hp) it needs a star/delta start. So, what you can do is, start the motor in star, using the live + neutral and with say 200uf starting capacitor between live and the 3rd leg on the motor. when the motor is up, switch into delta - simultaneously switching out the 200uf cap and switching in smaller ones, say 20/30uf to keep the motor currents balanced. YOu can do all this switching with 3 x 4 pole contactors, and a timer.

You mentioned you dont like processors - well my converter does'nt have any, but I do have plans to fit a PIC to control the star/delta switch over point instead of a timer, the reason for that is, sometimes the motor needs a little longer in star to come up to speed, this usually happens on very cold mornings, or if you're doing alot of stop/starting of the converter it usually does'nt need as long in star before it's up.

With the PIC, and using an optical sensor, my plan is (if it works ha!) is to fit the sensor with a flag on the shaft of the motor, and make the PIC monitor the RPM of the motor shaft and control switch over point on that basis instead of time, which is a bit too rigid.

There's lots on good info about converters on the web, I just figured out all this as I went along, I had many failures before I had success, I also nearly got killed by it! but that was my fault really - long story!


Hope this helps!
Dougal
 

oxygen454

New Member
I am wondering how to make a motor change direction after it has completed its forward cycle. Do you simpliy reverse the polarity of the AC on a standard electric motor?
 

Dougal

New Member
Yeah, well as for 3 phase motors you just swap any two of the phases, but
I don't know why you'd want to do this in a rotary converter?
 

oxygen454

New Member
I am not sure if the motor is 3 phase or not. All I know is I am getting a motor for a gate I am building for a acerage and I have to know how to make it open and then reverse to close as well as how to make it stop at a point of full open and stop at a point of full close.

Thanks for your help so far and in advance!
 

gandmelectrical

New Member
Hi i am busy with a bit of a project, i have stripped out the relay completely and i have installed contactors for a single phase motor, i still have the switching gear. my terminals are marked K1 K2 and M1 M2. the Cap is internally wired. There are 2 windings, how would i reverse the motor? Assistance would be greatly appreciated.
 
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