What is Zero Current Switching (ZCS)?

Zero Current Switching (ZCS) ensures that a relay contact is closed at the zero crossing and opened at the precise moment when zero current flows through it. This has a number of advantages for smart power devices using relay switching techniques. With less potential harm from inrush currents, there is less wear on the relay itself and greater protection for connected switch mode power supplies (SMPS). There is also significantly reduced electromagnetic interference from repeated switching On/Off. Opening a relay contact when the current is zero is important for inductive loads (motors, transformers) but less so for capacitive loads including switch mode power supplies (SMPS) of the type found in computers, servers and IT network peripherals.