I'm planning exactly the same project. (phase angle control of a vibratory feeder).
It would be nice to know how the problem was solved by the thread starter?

If a light bulb works, what about using a power resistor (5-11 watts) parallel to the load? Could this solve the issue?

Mod: link to old thread
https://forum.allaboutcircuits.com/...ng-triac-ac-power-control.195730/post-1846312

 

I'm planning exactly the same project. (phase angle control of a vibratory feeder).
It would be nice to know how the problem was solved by the thread starter?

If a light bulb works, what about using a power resistor (5-11 watts) parallel to the load? Could this solve the issue?

A resistive load could work but would be very wasteful. It is far better to use correction capacitors, to get as close to unity power factor as possible.
There are capacitors capable of very high currents, like the motor-run capacitors, which would serve this purpose.

 

A ZobeL network works better, but does introduce some resistive loss

 

Unfortunately, you will have to change the triac for some other device. The triac does not switch off until the current through it reaches zero,

Isn’t that exactly what you want? If there is no current through the triac, there is no current through the inductor, and therefore no energy stored n it. Isn’t that when you would want it to switch?

 

It is far better to use correction capacitors, to get as close to unity power factor as possible.
There are capacitors capable of very high currents, like the motor-run capacitors, which would serve this purpose.

Which kind of capacitors do you mean? Those which are used in EMI circuits?

 

No
I meant motor run capacitors, like so:

https://www.cityelectricsupply.com/...60UsZaS8BYJ0xbdo-otHuNKIyJOAMC8ISoAj7dQ&gQT=1

 

Isn’t that exactly what you want? If there is no current through the triac, there is no current through the inductor, and therefore no energy stored n it. Isn’t that when you would want it to switch?

It is precisely what is required, but if the load is inductive, the current reaches zero at some time in the following half-cycle. By that time the voltage is no longer zero, and that is the voltage that the TS is noticing.

 

Isn’t that exactly what you want? If there is no current through the triac, there is no current through the inductor, and therefore no energy stored n it. Isn’t that when you would want it to switch?

BOB has stated exactly what I was also Going to state: TRIACS and SCR devices switch off when the current falls below some small sustaining amount. Thus the current is already very low. BOB IS CORRECT!! so there is no problem. JUST READ the data sheet of the SCR or Triac device. Those devices require that the current and voltage be reduced to some very low value to switch off.