We all know of wattage ratings for resistors - I'm interested in specs on
>the
>voltage ratings of large resistors.
? depends on the unit. Globar makes some energy absorbing resistors
with much capability.
>2 watt carbon resistors and 1 watt
>carbon film resistors are rated at 500 volts. I presume that is to limit
>the voltage gradient
? True
>or stress across the resistor so that it doesnt act as a
>fuse or firecracker. What about large resistors often used as bleeders on
>hv power supplies?
The most reliable bleeder/equalizer resistor I have run into is a MOF
type made by Matsushita. We have sold over 6000 100k-ohm 3w units with
no failures reported. The max. rating is 500v (2.5w max.). If one is
not sure of the capabilities of a resistor, measure the current vs.
voltage very carefully with a DMM. . As long as current does not
increase faster than voltage, no internal breakdown is taking place.
>I use 200 watt resistors in series and have never had any
>problems. I assume they can stand hv due to their long length,
? good point. However, high bleeder current is definitely not justified
>about 10"
>long, to spread out the voltage gradient. Does anyone have any specs on
>their actual voltage rating? 73 Bob W7LR
>
depends on the resistance. 200w c. 100k-ohm ww resistors do not have a
reputation for high reliability. My guess is that the wire is pretty
flimsy. This is probably why they are typically not rated for 200w of
actual dissipation.
cheers, Bob
- Rich..., 805.386.3734, www.vcnet.com/measures.
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