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Re: Heat from pig resistance.
In a message dated 96-12-03 00:49:34 EST, you write:
<< <
Coilers; I've been reading alot lately about oven/dryer heating elements
being used for resistance in the above manner. But what about the level
of heat dissapated by these things during use? When connected in series
with the 240 volt winding of a pig a 5 KW heating element will probably
generate 2.5 KW, (50%), but that's still alot of heat. How do you
actually install these things; What precautions; Cooling fans?
Thanks, Daniel.
>>
Daniel,
I have six of the 2000 watt oven elements that I can use some or all in
parallel. Since they are insulated, you can mount directly to the element.
I have them in a stack with 1/2" angle iron pieces between each element and
all wired together to hold it tight. They just sit on the cement floor next
to the welder. They do get hot but not enough to need special cooling.
Ed Sonderman
>>
Daniel,
I forgot to mention that I was using the oven elements in parallel with the
welder. That is why they aren't too hot at this point, all 20 or 30 amps of
primary current wasn't flowing through the elements. I plan to try using
them in series and then they will probably get real hot. At 20 amps primary
current and 6 elements in parallel for a total of 4 ohms, it would dissipate
1,600 watts. At 30 amps primary current it would be 3,600 watts.
This points out a problem that I had not thought about - which is if the
resistance is used in series with the inductive ballast, you need much lower
resistance. I believe Richard Hull said he used .5 ohms. If I am going to
use 2000 watt oven elements, I would need 50 of these in parallel to get down
to .5 ohms. I can see why you need to go down to .5 ohms - if you use even 1
ohm at 30 amps, you are going to drop 30 volts across the resistor and loose
about 14% of your total input power right there.
For those who are using series resistance, what are you using?? It can't be
50 oven elements.
Ed Sonderman