Thyristor T901N

Question

The thyristor T901N in the Sinamics SL150 datasheet indicates constant operation limits based on temperature. In the datasheet, the continuous operation limits for this thyristor are as follows:

Current 940A at 85°C Current 1160A at 70°C Current 1350A at 55°C

This means that if you control the thyristor T901N at a current of 940A, the operational temperature should not exceed 85°C. If the current is 1160A, the operational temperature should not exceed 70°C, and if the current is 1350A, the operational temperature should not exceed 55°C.

The question here is whether anyone knows how controlling currents of 940A, 1160A, or 1350A would affect the temperature rise and cause continuous operation limitations based on the temperature restriction?

Answer 1

70°C Tc is the case temperature so you have to consider the heat sinks, air flow and ambient temperature as well as thermal resistance from case to heatsink.

The power dissipation of a thyristor in a cycloconverter application may not be all that easy to calculate or simulate. For a static switching application, all the information you need is in the 'hockey puck' thyristor datasheet.

You should rely on information from Siemens for the limitations of the complete product. If you want more information (like if you're reverse engineering or copying the Siemens product) refer to the GE SCR manual from the 1970s (can be found online).