Supervisory circuit

Supervisory circuits are electronic circuits that monitor one or more parameters of systems such as power supplies and microprocessors which must be maintained within certain limits, and take appropriate action if a parameter goes out of bounds, creating an unacceptable or dangerous situation.

The control circuit may either shut down the circuitry it is protecting, reduce the power available in order to avoid overheating, or notify the system (software or user).

The shunting creates a short circuit which removes power from the protected circuitry.

Fire Alarm systems often supervise inputs and outputs with an end-of-line device such as a resistor or capacitor.

The system looks for changes in resistance or capacitance values to determine if the circuit has an abnormal condition.