A power supply overheating protection circuit diagram

This article uses a temperature relay to detect the temperature inside the power supply device. When overheating occurs inside the power supply device, the temperature relay will act, putting the alarm circuit of the whole machine in an alarm state to realize overheating protection of the power supply. As shown in the figure (a) below, the P-type control gate thermal thyristor is placed near the power switching transistor in the protection circuit. According to the characteristics of TT102 (the conduction temperature of the device is determined by the Rr value, the larger the Rr, the higher the conduction temperature. Low), when the shell temperature of the power tube or the temperature inside the device exceeds the allowable value, the thermal thyristor will conduct, causing the light-emitting diode to light up and give an alarm. If it is combined with a photoelectric coupler, the alarm circuit of the whole machine can be activated to protect the switching power supply. This circuit can also be designed as shown in Figure (b), used as overheating protection for power transistors. The base current of the transistor switch is bypassed by the N-type control gate thermal thyristor TT201, and the switch is turned off, cutting off the collector current and preventing overheat.