Effects of running PWM to control fan motors

[stempile]

Renard with PWM driving SSRoz boards:

Will the PWM power supply connected to a fan (at 100%) over time damage the motor?

Application is controlling when an inflatable is inflated or not inflated. Anyone using PWM had issues or success with this?

ms

[cmurray]

My gut says yes.

I fried one Halloween inflatable last year. I think that was even before the PWM code.

The issue is that the triacs are not zero-crossing and no matter how close the pic code attempts to time it, it will never be exactly at zero.

I have one SSR box that has 4 hockey pucks that are used to control my inflatables and strobes.

General rule, no motors or electronics of any kind on homebuilt boards.
That means incandescents and LEDs only.

No problems this year yet.

JOel

[P. Short]

There is code in the current Renard firmware PWM versions that purports to turn the outputs on 100% of the time if the brightness level is set to 255. Someone wanted this change so that he could use zero-crossing opto-isolators. So I think that you could use the PWM code for simple on-off control of the fan motors (255 = on, 0 = off).

YMMV.

--

Phil

Edit -- there will probably be problems with the inductive load...I forgot about that.

--

Phil

[wjohn]

yup

add a snubber circuit, or use the DC SSR board and switch a contact relay.

[stempile]

Checking into it. Thanks.

Information on snubber: Wikipedia (http://en.wikipedia.org/wiki/Snubber)

ms

[Wayne J]

Also give this a read.......may be of help


http://www.christmasinshirley.com/forum/viewtopic.php?t=157&postdays=0&postorder=asc&start=0

[stempile]

I remember reading that... so long ago. Will brush up on that.

One thing that would be handy for the board is if someone or a group of someones went trough and update the subjects of the threads to be as specific as possible. Just looking at the subjects its hard to find some this again.

ms