Circuit analysis of solid-state automatic shutdown in case of power failure

The schematic diagram below is of the circuit? Solid state automatic shutdown in case of power failure.

There are definitely a lot of circuits present in EFY today that shut down power to the load in the event of a mains power failure. This circuit differs from other similar circuits in that it consumes no power when the load is off. Additionally, this circuit is completely solid state as it does not use any type of relays or many other electromechanical devices.

In this circuit, resistor R1, diode D1, capacitor C1 and zener diode D2 are used to develop a mains derived 9V DC power supply which feeds to the triac gate. Switches S1 and S2 are used to perform "off" and "on" operations respectively.

When switch S2 is pressed immediately, the neutral wire gets extended to MT1 of triac TR1. This in turn gives the transistor circuit access to DC voltage. Capacitor C2 and resistor R5 provide the initial base drive to transistor T2 when powered. By the time capacitor C2 is fully charged, transistor T1 is driven to saturation through transistor T2 and resistor R3.

The collector pin of transistor T1 is connected to the base of transistor T2 through resistor R4, and the collector of transistor T2 is connected to the base of transistor T1 through resistor R3, that is, there is a shared symbiotic relationship between transistors T1 and T2. As long as transistor T1 is on, it provides the necessary fence present in the triac via resistor R7. Capacitor C3 protects the circuit from spurious events.

The batch can be shut down by pressing switch S1 or turning off the power to the circuit. When switch S1 is pressed, transistor T1 is no longer in saturation, so it also turns off the triac and t. Since the rectifier circuit may not turn on when the triac is off, it certainly won't be dissipating power when the beam is off.

This idea can accordingly be used in cooking timer applications, where the power supply to the cooking timer circuit should be turned off after a series time delay. The optocoupler is able to change switch S1 to close using the output of the low voltage command circuit.