The influence of the temperature on the power structure behaviour

The functional limits of a thyristor are defined by an essential parameter: the allowable maximum junction temperature. It can be of 125°C. The technical specification of each type of thyristor gives the limit values of the functional temperature, which will be for example of 55°C to 125°C. The electrical energy dissipated in the thyristor at any direction of the current, appears under the form of a thermal energy across the junctions, where the total power lost in the crystal causes an increase of the junction temperature. In fact, this value represents only a very little part of the power available in the circuit. But it shouldn't be forgotten that the ambient temperature represents an energetic level from which, the increase of the junction temperature is done. However, this latter can reach a value relatively increased, especially if we know that the industrial ambient temperature is very often approximately equal to 50°C or 60°C.