** "The motor still spins easily" contradicts that idea.
Seen a few cheap Chinese fans with tight/stuck bearings - takes a fair bit of solvent to get them spinning again.
The OP has no so far bothered to open a fan a check the motor wiring for continuity.
... Phil
Deane:
What relay are you using? What is the the motor?
Some SSR bricks designed for this purpose have 3-32 V for an input and no series resistor is required. A heat sink with the appropriate thermal grease is. They have to be triac or back to back SCR's.
Some offer to switch at zero current. It should be random.
Some require series resistors.
Some SSR's are triacs, dual SCR's, SCR's (won;t work) or MOSFETS (won;t work).
ds a 6 VDC battery voltage to control a 120 VAC solid state relay which pow ers up the vent fan. The fans always quit within 2 months to a year with no obvious defects. These are inexpensive 20 inch box fans with induction mot ors. I have tried several brands and styles of fans. The latest was a Home Depot unit that only lasted 2 months.
a SS relay? What is killing the fans? I have taken two apart and there is n o smoke smell, no visible damage and if there is a capacitor it tests OK.
If you need the thermal fuse, please feel free to contact snipped-for-privacy@setfuse.co m. We are thermal fuse, MOV and thermal protected MOV manufacturer in China.
Any question, please do not hesitate to inform us.
Best Regards Leo
Yes he did, There is no continuity.. Which means it's been operating hot!
Jamie
Deane Williams wrote in news: snipped-for-privacy@googlegroups.com:
So you blew some fans. But what about the SSR? Is it suited for diving these motors? Some properties are as important as properties of a mechanical relay and even with the right specs it may be defective.
Then, what about the signal diving the SSR? If it comes from a mechanical switch, the contactbounce can damage or destroy the SSR which in turn can blow the motor(s). SSRs like to be driven by clean signals and tend to be much more unforgiving them their mechanical couterparts.
petrus bitbyter
" The motor still spins easily. There is no DC continuity from the power plug but I beleive this is normal for induction motors? "
** ".. from the power plug ... ".Box fans typically have timers, 3 way speed controls and tilt switches, any of which could be the real problem.
** Not likely with perfectly free bearing and no damage.
.... Phil
Hi Phil,
I don't think anyone read my quote (July 29) from a SSR (Omron) manufacturers' FAQ PDF about using non-motor rated SSRs with induction motors. As they said, as long as the SSR has sufficient rating to handle the start up current (etc.) there will be no problems for the SSR.
The only thing folks haven't considered is a voltage surge - that could take out the fan without harming the SSR. The wiring may have problems where the neutral fails in a sub-box leading to 240VAC going to a motor designed for 120 - the motor would not last long, yet wouldn't give obvious signs of failure as the internal overheat fuse would open quickly...
I have no other ideas unless he isn't giving the house elves enough food and clothing.
John :-#(#
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