Dimming Motors

[David Ashton]

Moving lights use stepper motors which are driven by electronics, these are not universal motors as used in drills, fans and power tools,you seem to be purposefully obtuse in not reading what was said instead of what you think was said.
I'll just say it once more, a universal type motor will run perfectly well off a dimmer, as a motor speed control is essentially the same as a dimmer, minus the choke and plus a capacitor, moving lights with stepper motors and synchronous motors will not work.The problem with saying that one should never run motors on dimmers is that you will look like an idiot when someone plugs a fan into a dimmer and it works fine, this destroys your credibility so that the person you gave the advice to will then try it on a synchronous motor and burn it out, this is why simplistic answers are counter-productive.
I must admit to being puzzled by the comment that drill motors are dc, all Australian and English drills run on ac.
The question was, "would I destroy the dimmer" and the answer is no, a dimmer which is protected against the huge currents which occur when a theatre lamp blows is not going to have any problem with a motor.

 

[TimOlson]

Hi Mr Ashton, I respect what you say, and I have read the entire thread. However, given the nature of controlbooth with a large percentage of members in the beginning of their career, I would never recommend running any motor from a dimmer. Focusing on best practices early on sets good habits. Someone such as yourself, with specialized knowledge and experience, operate at a higher level of expertise and are qualified to make the judgment to go "outside the rules". I see inexperienced people running moving lights from dimmers set at full; account execs who don't want to x-rent the non-dim distro come at me with "we do this all the time and it's never been a problem". Those people don't know how close to the edge they operate, or what the long-term effects those practices create.

So - in the mind of an inexperienced tech, if it's ok to run a fan from a dimmer, why not a chain hoist? They are both motors and if it's OK for one it's probably OK for the other, right? This type of logic occurs every day.

If someone tries to run a drill motor or power tool or fan from the CONVENIENCE outlet on my dimmers, I'm not happy. from the dimmer itself? Absolutely Not.

There are tons of things that are done incorrectly every day, like not terminating a DMX chain & running movers from a dimmer. Problem is, these practices work for a while---until they don't. when it all comes crashing down, when strange DMX problems come up during a show, when a moving light power supply quits working during a show, the people that end up being cheated are the attendees.

so in my mind I'm thinking about accepted best practices and learning good habits. I think there should be a clearly stated "rule" that says never run a motor from a dimmer. Once that is firmly established, then learn the exceptions. In this way we minimize confusion and maximize the professional production.

peace, Tim Olson