I have a resistive heater with a resistance of 18 Ohms. The heater is mounted on a job which has a thermocouple mounted on it. I need to use a SSR based controller to control the temperature measured by the T/C. As per my calculation I need to produce 1500 W. I have at my disposal a 230 V, 50 Hz power source, rated at 16A.
I plan to use an isolation transformer to drop the 230V to 165V with the SSR and the heater mounted on the secondary side.
My question: An SSR will generate a number of harmonics due to "chopping" of the sine wave. Question is will these harmonics lead to heat generation in the secondary winding of the transformer?
Best Answer
The SSR generates current harmonics, which in a single phase system will only disturb the power factor slightly. It's only in a 3 phase system that such harmonics do other bad things like exciting neutral currents.
While a reduced power factor means there will be more heating in your secondary (and primary) for the same heater power than would be caused by a unity power factor, the effect with an SSR is going to be negligible.