capacitors

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dferrara

Member
Location
Missouri
i have a 3 phase tanning bed and a wire that goes to one of the capacitors is burnt up. what is the safest way to discharge the capacitor? is this a sign the capacitor is bad?the bed has had the power turned off for 24 hrs.thank you
 

ron

Senior Member
Re: capacitors

On a somewhat related note, how does a tanning bed work? Why are there capacitors for a tanning bed? I've never seen one, and always assumed it was a series of specialized fluorescent lights that output the type of light needed for a tan.
 

mwdkmpr

Member
Re: capacitors

The safest way is through a resistor. However most capacitors have enough dieletric leakage that it will discharge itself in a couple of hours. But the way I do it is short the terminals with a screwdriver, I like to hear them pop! ;)

Are you sure it is a capacitor? I know of no reason why there would be any capacitors in a tanning bed.
 

bphgravity

Senior Member
Location
Florida
Re: capacitors

I believe tanning beds use capacitors as starters/ignitors for the lighting. They are usually quite small. I also belive tha NEMA/ANSI standards require discharge circuits in equipment that have capacitors. This discharge circuit is required to reduce the residual voltage to less than 50V nominal within one minute after the capacitor has been discharged. This same requiment can be found in Section 460.6 of the NEC.

Your best bet is to use at least 1K ohm resistor to short the leads for an added safety measure. :)
 

steve66

Senior Member
Location
Illinois
Occupation
Engineer
Re: capacitors

An old analog voltmeter is the best way to discharge the cap. Plus, you can see if it is discharged.

Bryan:

I also belive tha NEMA/ANSI standards require discharge circuits in equipment that have capacitors.
I don't think that standard would apply to a consumer appliance. It would also be almost impossible to implement for some appliances.

I believe microwave ovens are the most dangerous appliance to unsuspecting service people. They have a large cap. charged to a high voltage and is capable of delivering a very high current. Don't try shorting it with a screwdriver unless you are wearing arc flash protection.

Also CRT tubes act like capacitors. I don't know how, but they can manage to recharge themselves even after being discharged. They recharge more if they are given the "screwdriver" discharge. It is best to discharge them slowly through a hight voltage meter.

Steve
 
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