Triacs in Parallel

maybe magnetically coupled? i.e. a common mode choke with one winding flipped

In diodes, thermal current hogging happens at low current, where it doesn't matter so much. At high currents, diodes become ohmic with a positive TC, so start to share.

CM chokes are deceptive. They are spec'd for current at, basically, zero net flux. If you flip one winding and use them as a 2-terminal inductor, or run current the same way through both windings, they usually saturate at very low current.

It's 8 amps RMS, or peak, but this is only during the low (zero-voltage-switch) voltages at which the trigger is applied. The 240V is RMS as well. 50 Hz or 60 Hz are likewise full-cycle measures, not directly related to the instantaneous behavior at trigger time.

Not really. triacs don't like inductive loads

Use a common mode choke instead. (in a crossed over configuration).

You're no fun anymore. ;)

Cheers

Phil Hobbs

He means to take it apart and see how they make it work. A 16A triac is two 8A triacs in one package, right? Or maybe it's 16 - 1A triacs... Just sayin'

Jasen Betts wrote: ================

** Not if you avoid pulse firing. Use one of the opto triac drive chips ( MOCxx etc) OR a continuous stream of high frequency pulses transformer coupled to the gate. In both cases, keep the drive ON whenever you need the triac conducting. Driving transformer coupled ( ie 12V lamp) loads is a trap, as phase controlled the triacs may wind up conducing mostly in one polarity, burning the tranny out with DC. The idea of paralleling two triacs is very optimistic. One my latch ON first, preventing the other from doing so due to the low voltage ( under <1v) available from MT1 to MT2 at the time.

.... Phil

Any realistic inductor in series with the MT1 terminals is probably going to have at least 20-30 milliohms series resistance anyhow which should help share the current?

piglet