Leakage current protection device adapted to a wide variety of domestic and international applications

A leakage current protection device for use in an electrical system having a neutral lead, a ground lead, and at least one power line lead extending from a source of energy to a load comprising:

• a differential transformer having a core, opposed primary windings producing bucking fluxes representative of current to the load and current from the load, and a secondary winding;
• circuit opening means to open the power line lead in response to a trip signal generated in said secondary winding when a leakage current above a predetermined magnitude is detected;
• and
• a control means comprising;
• a rectifier to provide DC power from the power line lead to control circuitry for the protection device;
• first unidirectional current means connected from said protection device control circuitry to the neutral lead;
• second unidirectional current means connected from said protection device control circuitry to ground, said second unidirectional current means having a higher forward voltage drop than said first unidirectional current means;
• and
• third unidirectional current means connected from said protection device control circuitry to the neutral lead with a polarity opposite that of said first unidirectional current device;
• said control means providing power to actuate said circuit opening means in the event of a leakage current above a predetermined magnitude whenever any two of the power line, neutral and ground leads between the power source and the protective device remain intact and a voltage in excess of a predetermined minimum potential exists between said two intact lines.

A leakage current protection device for use in an electrical system having at least a neutral lead and a power line lead extending from a source of energy to a load comprising:

• a differential transformer having a cores opposed primary windings producing bucking fluxes representative of current to the load and from the load, and a secondary winding;
• power factor adjustment means connected across said secondary winding for tuning said differential transformer circuit to have a leading power factor, which permits the protective device to efficiently respond to pulsating DC signals over a large range of input voltages;
• regulating means acting in conjunction with said power factor adjustment means to permit the protection device to efficiently and effectively respond to a range of line-to-neutral AC input voltages varying from 70 to 264 volts;
• adjusting means to selectively set the protection device to respond to a leakage current in the nominal range of 6 to 30 milliamperes;
• an amplifier circuit to linearly amplify the output of said secondary winding and provide a stable trip signal under varying conditions;
• circuit opening means to open the power line lead in response to a trip signal being generated in said amplifier circuit as a result of a leakage current above a predetermined magnitude producing a current in said secondary winding;
• a supplemental secondary coil on said differential transformer;
• switch means to close the circuit to said supplemental circuit to simulate the occurrence of a leakage current in order to test the protection device;
• and
• time delay means to prevent current flow to the ground lead until said circuit opening means has been actuated by current flow to the neutral lead, thereby decreasing the chances that other protection devices in the electrical system would erroneously sense the test simulation as a leakage current.

A leakage current protection device for use in an electrical system having at least a neutral lead and a power line lead extending from a source of energy to a load comprising:

• a differential transformer having a core, opposed primary windings producing bucking fluxes representative of current to the load and current from the load, and a secondary winding;
• power factor adjustment means comprising capacitive means for tuning the inductance of said differential transformer so that said differential transformer circuit has a leading power factor, said power factor adjustment means connected across said secondary winding for permitting the protection device to respond to pulsating DC signals;
• a linear amplifier circuit to amplify the output of said secondary winding and provide a stable trip signal under varying conditions;
• and
• circuit opening means to open the power line lead in response to a trip signal being generated in said amplifier circuit as a result of a leakage current above a predetermined magnitude producing a current in said secondary winding.

A leakage current protection device for use in an electrical system having a neutral lead, a ground lead, and at least one power line lead extending from a source of energy to a load comprising:

• a differential transformer having a core, opposed primary/windings producing bucking fluxes representative of current to the load and current from the load, and a secondary winding;
• circuit opening means to open the power line lead in response to a trip signal generated in said secondary winding when a leakage current above a predetermined magnitude is detected;
• and
• control means to provide power to actuate said circuit opening means in the event of a leakage current above a predetermined magnitude whenever the power line lead is broken and the ground lead and the neutral lead are intact, and when the ground lead is broken and the power line lead and the neutral lead remain intact, and when the neutral lead is broken and the power line lead and the ground line remain intact, and a voltage in excess of a predetermined minimum potential exists between said two intact leads.

A leakage current protection device for use in an electrical system having a neutral lead, a ground lead, and at least one power line extending from a source of energy to a load comprising:

• a differential transformer having a core, opposed primary windings producing bucking fluxes representative of current to the load and current from the load, and a secondary winding;
• a supplemental secondary coil on said differential transformer;
• switch means to close the circuit to said supplemental secondary winding to simulate the occurrence of a leakage current in order to test the protection device;
• circuit opening means to open the power line lead in response to a trip signal generated in said secondary winding when a leakage current above a predetermined magnitude is detected, said circuit opening means including;
• a circuit breaker connected to open the power line lead when energized;
• a contactor to open the power line lead when de-energized;
• connector means for alternatively selectively connecting a single one of said circuit breaker and said contactor to a regulated voltage supply in the protection device;
• switch means responsive to a trip signal generated in said secondary winding when a leakage current above a predetermined magnitude occurs, said switch means energizing said circuit breaker when it is connected and de-energizing said contactor when it is connected;
• and
• control means to provide power to actuate said circuit opening means in the event of a leakage current above a predetermined magnitude whenever any two of the power line, neutral and ground leads between the power source and the protection device remain intact and a voltage in excess of a predetermined minimum potential exists between said two intact lines;
• and
• time delay means to prevent current flow to the ground lead until said circuit opening means has been actuated by current flow to the neutral lead, thereby decreasing the chances that other protection devices in the electrical system would erroneously sense the test simulation as a leakage current above a predetermined magnitude.

A leakage current protection device for use with either a single phase or a polyphase power system having a neutral lead, a ground lead and at least one power line lead extending from a source of energy to a load comprising:

• a differential transformer having a core, opposed primary windings producing bucking fluxes representative of current to the load and current from the load, and a secondary winding;
• connecting means to ensure that either a single phase or polyphase input will properly energize the protection device;
• circuit opening means to open all power line leads in response to a trip signal generated in said secondary winding when a leakage current above a predetermined magnitude occurs;
• and
• control means to provide power to actuate said circuit opening means in the event of a leakage current above a predetermined magnitude whenever a power line lead is broken, and the ground lead and the neutral lead are intact, and when the ground lead is broken and a power line lead and the neutral lead remain intact, and when the neutral lead is broken and a power line lead and the ground line remain intact and a voltage in excess or a predetermined minimum potential exists between said two intact leads.

A leakage current protection device for use in an electrical system having a neutral lead, a ground lead, and at least one power line extending from a source of energy to a load comprising:

• a differential transformer having a core, opposed primary windings producing bucking fluxes representative of current to the load and current from the load, and a secondary winding;
• a supplemental secondary winding on said differential transformer;
• switch means to close the circuit to said supplemental secondary winding to simulate the occurrence of a leakage current in order to test the protection device;
• circuit opening means to open the power line lead in response to a trip signal generated in said secondary winding when a leakage current above a predetermined magnitude is detected;
• control means to provide power to actuate said circuit opening means in the event of a leakage current above a predetermined magnitude whenever any two of the power line, neutral and ground leads between the power source and the protection device remain intact and a voltage in excess of a predetermined minimum potential exists between said two intact lines:
• and
• time delay means to prevent current flow to the ground lead until said circuit opening means has been actuated by current flow to the neutral lead, thereby decreasing the chances that other protection devices in the electrical system would erroneously sense the presence of a leakage current above a predetermined magnitude if the neutral lead is unbroken.