What is the frequency range in which the average on-state current rating can be applied?
The frequency is usually limited to a range of 50 to 400 Hz. This is because, if the frequency is too low, the junction temperature could rise beyond the permissible value while the on-state current flows. The reason for the upper limit of the frequency is that, as the frequency increases, the temperature inside the thyristor unevenly rises, exceeding the rating at some parts even if the average temperature is within the permissible range.
|Diodes for Constant Voltage|