What is the purpose of a power supply interlock?

An interlock switch is a crucial safety device built into the physical housing of electronic equipment, particularly high-voltage power supplies or amplifiers. Its primary job is to automatically disconnect the main AC power and safely discharge capacitors whenever the cabinet or access door is opened. This mechanism ensures that an operator or technician cannot accidentally come into contact with lethal voltages while inspecting or repairing the internal components of the unit. The other options describe thermal shutdowns or over-voltage protection circuits, which monitor electrical or temperature states rather than the physical state of the cabinet.