Re: dumping a lot of heat

john larkin <jl@glen--canyon.com> wrote:

I'm thinking about building a biggish rackmount dummy load box. It
would simulate series resistance and inductance. Part of the problem
is that it will need to dump a lot of heat.
 
We are using copper CPU coolers on PC boards, which are great up to a
couple of hundred watts, but I'd like to do a kilowatt or two.
 
https://highlandtechnology.com/Product/P945
 
It would take a heap of expensive extruded heat sinks and fans to get
rid of a kilowatt. At 1 K/W, a pretty good heat sink, that's 1000 degC
temp rise.
 
A small hair dryer can dump a kilowatt. So some sort of red-hot
nichrome coils and a vicious fan might work.
 
I'd prefer to not use water.
 
I wonder if there is some sort of runs-red-hot power resistor.

Cooker hob ring?

I once used three industrial fan heaters as the starting resistor for a
large 3-phase motor with a big inertial load.  They were wired in delta
but connected to the star point of the motor - an arrangement which gave
the required starting current and torque.  After a predetermined time, a
normal 3-phase contactor shorted them out and closed the star point,
allowing the motor to run up to full speed.  The system worked
flawlessly, up to 8 times a day, for several years.

--
~ Liz Tuddenham ~
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