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variac humming
Posted:
Mon Jan 20, 2014 12:41 pmby nyazzip
i have a 10 amp variac (that has maybe a 7 amp fuse in it) that i noticed humming intermittantly this summer when the switch is on, and seems like it might be getting worse. this happens even when there is no load attached to it. it is quite noisy....sounds like 60hz.
is something going wrong...? is it going to burn down the house when i'm gone? or not to worry?
Re: variac humming
Posted:
Mon Jan 20, 2014 4:37 pmby azazello
If I leave home, I switch off all and 2 time check....
Re: variac humming
Posted:
Mon Jan 20, 2014 6:56 pmby DeathRex
Swing Low, Sweet Chariot?
Re: variac humming
Posted:
Mon Jan 20, 2014 7:15 pmby Geek
Different loads on the line can make a transformer or VARIAC sing. It's due to asymetrical waveforms.
Unless it's getting hot, I'd not worry about it.
But unplugging things while not home is a good idea. I have my entire bench circuit on a switch.
Cheers!
Re: variac humming
Posted:
Mon Jan 20, 2014 8:28 pmby nyazzip
i did recently move, so there is plenty of industry all around me now...i live about 2 miles from Chicago O'Hare airport now. maybe that's why i am hearing things
Re: variac humming
Posted:
Tue Jan 21, 2014 3:45 amby bone
Carbon dust from the brush contact can partially short adjacent windings. Give it a good clean and then check.
Re: variac humming
Posted:
Tue Jan 21, 2014 7:13 amby Geek
bone wrote:Carbon dust from the brush contact can partially short adjacent windings. Give it a good clean and then check.
An indication of this is if the unit smells. Does it, nyazzip?
Re: variac humming
Posted:
Tue Jan 21, 2014 12:17 pmby nyazzip
bone wrote:
Carbon dust from the brush contact can partially short adjacent windings. Give it a good clean and then check.
An indication of this is if the unit smells. Does it, nyazzip?
no odor or heat, but i did raise a ton of dust in the past 8 months with drywall/spackle and such...maybe i'll clean 'er up a bit