[SML] funky power

[tech dept]

Let me guess.
A loose screw on a branch panel breaker (3-phase). With a three phase motor under load, somewhere else in the building and the contact was heating up on the crest of the sine wave and dropping out.
On the backside of the sine wave don't expect ringing so I'm not looking at false triggering from dv/dt. Different brand substitution similar problems tosses out the filtering/regulation question on the triggering ramp circuit. I'm at a loss why your AC dimmers are so touchy.
So, what was the cause?
You got me very curious.

> -----Original Message-----
> From: stagecraft at theatrical.net
> Sent: Tue, 17 Feb 2015 19:36:56 -0800
> To: stagecraft at theatrical.net
> Subject: [SML] funky power
> 
> I was testing some lighting controllers today and the lights started
> flickering. Thinking I had a bad part on the controller I tested another
> brand new one.  Nope, did the same thing.  ??  Bad run of parts?
> Grabbed an old one made in 2008, did the same thing.  AHA!  Swapped out
> the dimmer for another one of a different brand.  Different flickering
> but still there.  !!!  New DMX cable?  Nope.
> 
> Grabbed a DC dimmer and powered it from a regulated DC supply.  All is
> good.
> 
> Put a 'scope on the AC line and we've got a funny looking waveform, it's
> depressed on the falling side with no dimmers running in the building.
> Sort of reverse what you'd see from running a large switching supply.
> ???
> 
> Anyway, ALWAYS test everything before tossing everything out the window
> and heading for the bar.  :)
> 
> --
> Jerry Durand, Durand Interstellar, Inc.  www.interstellar.com
> tel: +1 408 356-3886, USA toll free: 1 866 356-3886
> Skype:  jerrydurand
> 
> 
> 
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