Dual-mode ground-fault/leakage-current interrupter (GFCI/LCDI) interrupter and self-test/end-of-life (STEOL)

A dual-mode ground-fault and leakage-current interrupter (DMGI) for interrupting current between supply terminals and load terminals via line and neutral conductors, comprising:

• switching circuitry operable between a closed state connecting the supply terminals to the load terminals and an open state disconnecting the supply terminals from the load terminals;
• series-connected shield conductors surrounding the line and neutral conductors;
• a single differential-current sense transformer encircling the line and neutral conductors and producing a secondary signal representative of current imbalance;
• ground-fault detection circuitry coupled to the secondary signal and configured to generate a ground-fault trip signal when a ground-fault criterion is satisfied;
• leakage-current detection circuitry configured to detect conductor-to-shield leakage and shield-integrity faults and to generate a leakage trip signal;
• shield-monitoring circuitry configured to detect open or high-resistance conditions in the series-connected shield conductors;
• and
• a bi-stable electronic latch circuit operatively coupled to the switching circuitry and configured, in response to either the ground-fault trip signal or the leakage trip signal, to place the switching circuitry in the open state, wherein the bi-stable electronic latch circuit is responsive to the shield-monitoring circuitry.

A dual-mode ground-fault and leakage-current interrupter (DMGI) for interrupting current between supply terminals and load terminals via line and neutral conductors, comprising:

• switching circuitry operable between a closed state connecting the supply terminals to the load terminals and an open state disconnecting the supply terminals from the load terminals;
• a single differential-current sense transformer encircling the line and neutral conductors and producing a secondary signal representative of line/neutral current imbalance;
• ground-fault detection circuitry coupled to the secondary signal and configured to generate a ground-fault trip signal when a ground-fault criterion is satisfied;
• a leakage/continuity detection function associated with a flexible cord set, the function including series-connected shield conductors respectively surrounding the line and neutral conductors and shield-monitoring circuitry configured to detect open or high-resistance shield conditions and/or conductor-to-shield leakage, the shield-monitoring circuitry comprising:
• a sense supply and sense return forming a detector-domain power source;
• an open-shield (OS) detector coupled to the sense supply through the series-connected shield conductors;
• an OS trigger driven by the OS detector, and
• an isolated trigger coupler (ITC) having an input side connected between the sense supply and the OS trigger and an output side referenced to a trip/actuation retum, the ITC being operative to convey a control state to a trip stage and thereby provide a leakage trip signal;
• a bi-stable electronic latch circuit operatively coupled to the switching circuitry and configured, in response to either the ground-fault trip signal or the leakage trip signal, to place the switching circuitry in the open state;
• a grounded-neutral detection load (GNDL) connected across the load-side line and neutral conductors;
• and
• a self-test module comprising:
• a simulated ground-fault generator;
• a relay-synchronized switch configured to temporarily suppress normal ground-fault detection during self-test;
• an auto-monitoring logic module configured to determine whether self-test fails;
• and
• an end-of-life switch operable to disconnect the supply terminals from the load terminals in response to a self-test failure indication.