I have a PID/heater setup I am driving with an arduino. I'm using the Opto 22 MP240D4 solid-state relay to switch about 1A 120V 60 Hz (resistive heater). It's not clear from the product sheet or the datasheet whether it is zero-cross turn-on, or not. Also, just a bit of context, the application is a very low mass heating element, so it is a bit unusual from the perspective of typical PID plants.
I want to minimize the granularity of the pulse width/density modulation so as to get the best performance out of the system.
Obviously, my absolute upper bound is 120 Hz since that's the number of zero crosses. But is there any harm (in terms of thermal fatigue, stresses to the chip, etc) to running it at high pulse speed?
Also, is there any advantage to either pulse-width or pulse-density modulation?