Controlling AC motors

[The Master]

Hi. Ive got some 240V AC motors. When they power up they can spin either way and it appears to be random which way they actually spin. Is it possible to make them spin in a certain direction? Could it have something to do with the AC sine wave? Maby the direction depends on where the sinewave is when the motor powers up

[Acetronics2]

didn't you forget the starting capacitor somewhere.... ???

Alain

[The Master]

didn't you forget the starting capacitor somewhere.... ???

Alain

Theres no external capacitors or anything on these motors. Should there be?

[mackrackit]

If the motors are not 3 phase then they will have a starting cap or in small motors could have a starting winding that drops out at a certain speed.

You are correct about the sine wave, that is why the above is needed.

[The Master]

ok. there must be one built into it. does that mean it is or isnt possible to control the direction?

[mackrackit]

ok. there must be one built into it. does that mean it is or isnt possible to control the direction?

Do you have the make and model number of the motor?

[The Master]

They are Rotalink 5025-24050-30B. Google found nothing and i cant find that exact model on their site. shame they dont have a search box

[Acetronics2]

They are Rotalink 5025-24050-30B. Google found nothing and i cant find that exact model on their site. shame they dont have a search box

Decoding their code ...

shows 5024 is a 24 mm thick case and 5025 a 25 mm thick case ...

You'd better send them a mail ... for your problem !

Alain

[The Master]

This is a general question for any motors like that. There are some others that i would like to do the same thing with but i dont know the numbers of those.

It seems like they were designed to move in a random direction. I just want to know what causes the randomness so maby i can make it predictable.

Not sure about these motors but the other ones i have will change direction if you stop them with your hand.

I think i might end up with a simple on/off circuit instead of directional control

[Luciano]

Hi,

What is the number of leads coming out of the motor?

Best regards,

Luciano

[The Master]

Just 2. Its not a stepper motor (shame)

[Luciano]

Hi,

If your AC synchronous motor has only two leads (one winding), then
you cannot control the initial direction unless the motor uses a
mechanical device (anti-return) which is placed on the rotor.

Reversible AC Synchronous Motors have 4 leads or more. (Two windings or more).

* * *

Example of Reversible AC Synchronous Motor:
http://img250.imageshack.us/img250/4906/synmotormd9.png


Best regards,

Luciano

[mackrackit]

As you have probably figured out by now the "B" stands for Bidirectional.

Motors like this are designed to change directions under a certain load or if stopped. (light bar in scanner?)

Like Alain said, contact the manufacturer to find out how they did it in this motor but it is most likely like Luciano shows with the CW/CCW built in on an actuator. Now if you feel lucky take one apart and see if they can be bugged into.

[The Master]

I see. I was hoping there would be a controllable reason why they go a random direction on startup. I will just make a simple on/off circuit for them then.

mackrackit, they are in abstract twister 3's

Thanx everyone for your help

[mackrackit]

mackrackit, they are in abstract twister 3's
You have lost me, but it has been a long day.

[Luciano]

You have lost me, but it has been a long day.

Hi Dave,

I had to google in order to find out.

The new Twister 4:
http://www.abstractavr.com/products/twister4.php

http://img525.imageshack.us/img525/8152/discowb0.png

Best regards,

Luciano

[The Master]

Yeah. I should upgrade to twister 4's. All my other FX lights are DMX. The new stuff is just too expensive though. I would like to Martin MX-4's. Im still using the MX-1's. lol.

[mackrackit]

Thank you Luciano. Those were the days when I had to explain to people that the Commodore 64 was not a band including Lionel Richie :eek:

Master, You may want to look at RS485 http://en.wikipedia.org/wiki/RS-485 . I have not done this with a PIC but many have. You are new here so here is a link to the archive http://list.picbasic.com/cgi-bin/board-search.cgi .

[The Master]

What is that for? Ive not read the entire article but it appears to be about data communication rather than motors

[mackrackit]

What is that for? Ive not read the entire article but it appears to be about data communication rather than motors

OPPS wrong thread, but it would apply to your serial many PIC project.

[The Master]

Ive had a more detailed read of it. It looks clever but im not sure how i would use it. Would i buy converters or would i have to program the chips and use standard I/O?

[mackrackit]

Yes, you would need a 232 to 485 converter, the programing would be the same.
Big advantage is distance and "multiple devices".
If you interested search the forum, several discussions about converters, suppliers, and such. I have not used 485 enough to know all of the ins and outs, just enough to know it works well.

[The Master]

Sounds good. Im not doing long distance stuff yet but i will be in the future i hope. Maby only 1 or 2 hundred meeters though. In any case i will probly be using at least 10 chips on each dataline

[mackrackit]

Forgot to mention that the first time I used it was in a situation with a lot of electrical noise. Sending date to a CNC plasma machine RS232 was not reliable and RS485 solved the problem.
Good luck.