On 29 Jul 15 at group /sci/electronics/repair in article
(Pat) wrote:

On Wed, 29 Jul 2015 08:12:51 -0700 (PDT), Deane Williams
wrote:



Hard to see where a SS AC Relay could hurt an induction motor if
the motor isn't overheating.

Does the fan still spin? Is there continuity in the winding?

John :-#)#

The motor still spins easily. There is no DC continuity from the
power plug but I beleive this is normal for induction motors?
Perhaps the overheat sensor has opened permenently. Home Depot
gave me a replacement so I will try it again. These fans typically
last for many years when plugged directly into a wall socket. This
is a real mystery to me. Perhaps SS relays generate some large
spikes on their output? I should check it with a scope.
Thanks for the comments.

You have an interesting problem. I hope you figure it out. I have
never used SS relays, but I can't image they cause spikes and other
anomolies that would kill a simple AC motor. Is the relay rated for
inductive loads?

By the way, I have a similar fan I purchased years ago. I just
measured its DC resistance and found it to be about 18 ohms on its
high setting. Clearly, that number is no indication of its impedance
at 60 Hz while in operation, but it definitely conducts DC. My best
guess is something is causing the motor windings to overheat and
eventually open. Unfortunately, I can't think of any way to explain
why that would happen.

I think but don`t know!
If the SSR is bad (or not designed for inductive load) it may have
different half wave signals, so a DC current may flow thru the motor and
heats the coil (too much). A light bulb didn`t show any defects, because
it converts all current to heat and a little light

Just my 2 cent.

I will recommand a true mechanical relay for this job.


Saludos (an alle Vernünftigen, Rest sh. sig)
Wolfgang

--
Wolfgang Allinger, anerkannter Trollallergiker reply Adresse gesetzt!
Ich diskutiere zukünftig weniger mit Idioten, denn sie ziehen mich auf
ihr Niveau herunter und schlagen mich dort mit ihrer Erfahrung!
(lt. alter usenet Weisheit) iPod, iPhone, iPad, iTunes, iRak, iDiot