On 7 December 2015 at 15:53, Jon Elson <[email protected]> wrote:
> I would just get some vitreous enamel resistors.  They are
> not that expensive, even new.

Or higher-power lower-resistance for a faster discharge.
http://www2.mouser.com/search/ProductDetail.aspx?R=0virtualkey0virtualkeyTHS50560RJ

As the capacitance and voltage rise you get to the point that the
bleed-of resistor becomes an electric heater, but I think you may be
below that point.

My mill has 6600uF at 300V, and I wanted a 10 second discharge
That means a 500R resistor,
A 500R resistor permanently across a 300V bus dissipates 180W. And
that's a pretty big resistor. Which is why, in my case, I decided to
only switch-in the resistor at power-off.

With less capacitance, and lower voltage, the power requirement falls
rapidly. (with the square of V).

120V and 3300uF comes out at a far more reasonable 14W with a 1K resistor

-- 
atp
If you can't fix it, you don't own it.
http://www.ifixit.com/Manifesto

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