OK, so what happens to a BE junction when it is exposed to more than its PIV voltage? It will die, if not immediately then over time, taking the SCR out with it. It isn't shown for the triac, why I'm not sure.

Does you're simulation include the Gate Cathode resistor? I suspect it doesn't. This is a pretty important part of the circuit, even if it isn't shown.

 

For what it's worth I just dug out a very old textbook I used when I was in college, "Industrial Electronics, Design and Application", by Charles A Davis, page 144. It concurs with both the schematics and what I've been saying.

I'll go back to what I said in the beginning, if this chapter wasn't changed at all it would not be that important. The most I think needs done is an acknowledgment that the AC waveform is conceptual, and in practice will be heavily distorted from the ideal.

 

Hello,

Take a look at the following application notes.

Greetings,
Bertus

 

I saw the first one in my travels. The next two I missed. Right now the question is simple, will the AAC schematic work or not? I have 3 independent sources confirming it so far, only one shows the exact same configuration though.

 

Hello,

On page 2 of this application note there are diodes used in series with the gate to reduce the sensitivity.

All the application notes posted can be found on this page:
http://www.littelfuse.com/design/ap...n-notes.html#ElectricalIndustrial_Electronics

Greetings,
Bertus

 

Right now the question is simple, will the AAC schematic work or not? I have 3 independent sources confirming it so far, only one shows the exact same configuration though.

1. Will it work?

Ans. Yes, if the phase control range is less than 90 degree. The triggering relies on a series resistor to limit the gate current and the slowly increasing gate drive current ultimately trigger the gate.

However, it did not work properly if the phase angle is larger than 90 degree, using a capacitor to delay the voltage/current. Simulation shows that the voltage on the capacitor is never more than a (few) volt(s) because of the flow of gate current before triggering.

2. Only one shows the exact same configuration though.

Ans. If this would not be some hints to tell you something is not quite right I don't know what would.

3. What happens to a BE junction when it is exposed to more than its PIV voltage? It will die.

Ans. A diode should be fitted across the capacitor to prevent this from happening. One can even place a diode in series with a diac in this case.

4. Does you're simulation include the Gate Cathode resistor?

Ans. If the resistor exists internally to the SCR, it would have already been included in the SPICE model provided by the manufacturer.