Under/Over Voltage and Current Protection Switch

This simple project allows users to design an under-voltage, over-voltage, under-current, and over-current protection switch. It is a highly useful system for safeguarding electrical loads against abnormal power or current conditions.

The project features a relay with optocoupler input, a current-sensing circuit based on the INA195 amplifier, a 10mΩ shunt resistor, and a voltage divider network for voltage feedback. It is primarily designed for low-voltage and low-current applications up to 4A, but the relay can handle loads up to 5 A at supply voltages up to 48 V.

The system can be easily controlled using an Arduino or other microcontroller. Voltage and current feedback signals are fed into the microcontroller’s ADC pins for measurement, while the relay can be switched using a 5 V control signal from the processor.