triggered SG

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Pete Komen by way of Terry Fritz <twftesla-at-qwest-dot-net>" <pkomen-at-zianet-dot-com>

For Terry,

You suggest a 400 Watt resistive load for the dimmer and use 25 ohms.  I
have several questions:

25 ohms at 120 VAC is 576 Watts.

With a dimmer is rated at only 600 Watts, isn't a 576 Watt load (not
counting the coil) a bit much?  The load may not draw that much, but I would
expect that the dimmer is rated that way (IOW, a load that draws 600 Watts
at 120 volts is maximum for the dimmer, regardless of the actual wattage
drawn with the dimmer in the circuit).    Also, 576 Watts seems like it is
pushing the limit for 2-225 Watt power resisters.  BTW, I have run power
resisters way over their limits, but not for long and they got HOT fast.

Does the dimmer reduce the load to 400 Watts?  Did you measure the power
consumed by the resistance?  How critical is that load?

Would 36 ohms (400 Watts at 120 VAC) be OK or better?  Would 40 ohms do the
job (360 Watts at 120VAC)?

Digi-key has 300 watt resisters of 12, 16, or 20 ohms at about the same
price as the 50 ohm, 225 Watt resisters.  Two of those in series should work
and give a range of values near 25 ohms.  For example: a 16 ohm and 20 ohm
in series would consume 400 Watts at 120 VAC.  The 20 ohm resister would
dissipate 222 Watts.

Regards,

Pete Komen

I have a degree in Math; does it show? ;-)