LCDI power cord system and method
A system and method for an LCDI power cord and associated circuits is provided. The system and method include energizing shielded neutral wires and shielded line wires and monitoring the energized shields for surges, e.g., arcing, detected by a Leakage Current Detection Circuit (LCDC) and/or voltage drops, e.g., shield breaks, detected by a Shield Integrity Circuit (SIC).
1. A Leakage Current Detection Interrupter (LCDI) circuit for interrupting AC power from an AC source connected to a load via an insulated neutral wire surrounded by a neutral wire shield (NWS) and an insulated line wire surrounded by a line wire shield (LWS), the LCDI circuit comprising:
a power supply circuit for supplying a rectified waveform;
a floating load connected to the power supply circuit, wherein the floating load comprises:
a leakage current detection circuit (LCDC) for detecting leakage current from the insulated neutral wire or the insulated line wire, wherein the LCDC further comprises
a first bi-stable latch device having on/off states and connectable to the NWS;
a first charge holding device connected to the first bi-stable latch device for biasing the first bi-stable latch device towards the on state;
a shield integrity circuit (SIC) for monitoring the NWS and LWS integrity;
a mechanically latched double pole switch disposed between the AC source and the load; and
a solenoid for delatching the double pole switch.
2. The LCDI circuit as in claim 1 wherein the first bi-stable latch device comprises:
the first bi-stable latch device latched on when the voltage on the first charge holding device exceeds a first latching voltage; and
the mechanically latched double pole switch unlatched when the voltage on the first charge holding device exceeds the first latching voltage.
3. The LCDI circuit as in claim 1 wherein the SIC comprises:
a first npn transistor connected to a second bi-stable latch device having on/off states, the first npn transistor being selectively turned on and off based upon sufficient application of a portion of the rectified signal positive pulse to a base of the first npn transistor.
4. The LCDI circuit as in claim 3 comprises the first npn transistor selectively turned off based upon insufficient application of the portion of the rectified signal positive pulse to the base of the first npn transistor.
5. The LCDI circuit as in claim 4 comprises:
the second bi-stable latch device latched to the on state when the first npn transistor is selectively turned off; and
the mechanically latched double pole switch unlatched when the second bi-stable latch device latched to the on state.
6. The LCDI circuit as in claim 1 wherein the power supply circuit comprises a full wave bridge rectifier.
7. The LCDI circuit as in claim 1 wherein the power supply circuit comprises a half wave rectifier.
8. The LCDI circuit as in claim 1 wherein the floating load further comprises an immersion detection circuit.
9. The LCDI circuit as in claim 1 wherein the floating load further comprises a light detection circuit.
10. A leakage current detector interrupter (LCDI) circuit for interrupting continuity between an AC line power connector and an AC load connector, the LCDI circuit comprising:
a conductive neutral wire shield;
a conductive line wire shield;
a power supply circuit for supplying a rectified signal electrically connectable to the conductive neutral wire shield and the conductive line wire shield, wherein the power supply circuit comprises a floating load circuit, where the floating load circuit comprises:
a leakage current detection circuit (LCDC) connected to the conductive neutral wire shield and the conductive line wire shield, wherein the LCDC further comprises;
a first bi-stable latch device having on/off states and connectable to the NWS;
a first charge holding device connected to the first bi-stable latch device for biasing the first bi-stable latch device towards the on state;
wherein the first bi-stable latch device comprises:
the first bi-stable latch device latched on when the voltage on the first charge holding device exceeds a first latching voltage; and
the mechanically latched double pole switch unlatched when the voltage on the first charge holding device exceeds the first latching voltage;
a shield integrity circuit (SIC) for monitoring the integrity of the conductive neutral wire shield and the conductive line wire shield;
a mechanically latched double pole switch disposed between the AC line power connector and the AC load connector; and
a solenoid for delatching the mechanically latched double pole switch and interrupting continuity between the AC line power connector and the AC load connector.
11. The LCDI circuit as in claim 10 wherein the SIC comprises:
a first npn transistor connected to a second bi-stable latch device having on/off states, the first npn transistor being selectively turned on and off based upon sufficient application of a portion of the rectified signal positive pulse to a base of the first npn transistor.
12. The LCDI circuit as in claim 4 wherein the SIC further comprises:
the first npn transistor selectively turned off based upon insufficient application of the portion of the rectified signal positive pulse to the base of the first npn transistor;
the second bi-stable latch device latched to the on state when the first npn transistor is selectively turned off; and
the mechanically latched double pole switch unlatched when the second bi-stable latch device is latched to the on state.
13. The LCDI circuit as in claim 10 wherein the power supply circuit comprises a full wave bridge rectifier.
14. The LCDI circuit as in claim 10 wherein the power supply circuit comprises a half wave rectifier.
15. A leakage current detector interrupter (LCDI) circuit for interrupting continuity between an AC line power connector and an AC load connector, the LCDI circuit comprising:
a conductive neutral wire shield;
a conductive line wire shield;
a mechanically latched double pole switch disposed between the AC line power connector and the AC load connector;
a solenoid for delatching the mechanically latched double pole switch and interrupting continuity between the AC line power connector and the AC load connector;
a power supply circuit for supplying a rectified signal electrically connectable to the conductive neutral wire shield and the conductive line wire shield, wherein the power supply circuit comprises a floating load circuit, where the floating load circuit comprises:
a leakage current detection circuit (LCDC) connected to the conductive neutral wire shield and the conductive line wire shield, wherein the LCDC comprises:
a first bi-stable latch device having on/off states and connectable to the NWS;
a first charge holding device connected to the first bi-stable latch device for biasing the first bi-stable latch device towards the on state, wherein the first bi-stable latch device comprises:
the first bi-stable latch device latched on when the voltage on the first charge holding device exceeds a first latching voltage; and
the mechanically latched double pole switch unlatched when the voltage on the first charge holding device exceeds the first latching voltage;
a shield integrity circuit (SIC) for monitoring the integrity of the conductive neutral wire shield and the conductive line wire shield, wherein the SIC comprises:
a first npn transistor connected to a second bi-stable latch device having on/off states, the first npn transistor being selectively turned on and off based upon sufficient application of a portion of the rectified signal positive pulse to a base of the first npn transistor;
the first npn transistor selectively turned off based upon insufficient application of the portion of the rectified signal positive pulse to the base of the first npn transistor;
the second bi-stable latch device latched to the on state when the first npn transistor is selectively turned off; and
the mechanically latched double pole switch unlatched when the second bi-stable latch device is latched to the on state.
16. The LCDI circuit as in claim 15 wherein the power supply circuit comprises a full wave bridge rectifier.
17. The LCDI circuit as in claim 15 wherein the power supply circuit comprises a half wave rectifier.