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Re: Resistance of Oven Element
On Mon, 13 May 1996, Tesla List wrote:
> From: Chip Atkinson <chip-at-grendel.objinc-dot-com>
> I originally opted for two oven elements and put them in parallel with my
> arc welder. However, whenever I would close the contactors (push the button),
> the 40A circuit breaker would blow. I don't exactly understand why, except for
> the possibility of a sudden surge of current to energize a 10KVA pole pig.
> When I took out one of the elements, I didn't have the breaker trip problem,
> so that's where I am forced to stay for now. My ohmmeter died, so I can't tell
> what the resistance is.
You could use the same system I use in my control panel now - this enables
me to use the control panel even with 10A fuses that would otherwise
blow.. I do have 250 ohm power-resistor in series with the system thus
limiting initial rush current to appropriate level. After switching the
main-switch on I push another switch that switches on a contactor that
short-circuits the 250ohm resistor and thus allows full currect - at
this moment the cores have energized.
Ascii art:
---250-ohms-----
| |
-------o--contactor---o----
mains control panel
---------------------------
I do shall use a variable time switch for the contactor as soon as I can
so that it switches the contactor on after a variable amount of seconds
from the main switch closing..
This same way should work on your system - and that additional 250ohm (or
something like that) resistor is easy to add.. I think it will ease the
initial stress on equipment as well.. 250 ohm resistor will pass a current
of about 1 amp and thus P=UI=RII=250 watts.. Perhaps using a halogen light
bulb will the cheapest option if one does not have 1k 100W resistors lying
around like I had.. Typical 300W bulb will cost 1-2 USD..
I hope this helps,
Kristian Ukkonen.