An improved overload relay includes a number of current transformers that draw power from a circuit it protects to power itself. The current transformers charge a capacitor which powers a processor and which can energize a solenoid to initiate the interruption of the circuit. The overload relay further includes a capacitor analysis circuit which detects an operational parameter of the capacitor and enables a processor to determine when the energy storage capability of the capacitor has dropped to a predetermined threshold. In the event of such a determination, the overload relay can perform any of a number of actions.