Arc fault circuit interrupter and circuit breaker having the same

• US 6,532,139 B2
• Filed: 05/10/2001
• Issued: 03/11/2003
• Est. Priority Date: 05/12/2000
• Status: Expired due to Fees

• Current Assignee: Seochang Electric Communication Company Limited
• Original Assignee: Human El-Tech, Inc.
• Inventors: Kim, Jeong-Wan, Kim, Cheon-Youn
• Primary Examiner(s): HUYNH, KIM NGOC
• Application Number:
  US09/852,117
• Publication Number:
  US 20020008950A1
• Time in Patent Office: 670 Days
• Field of Search: 361/42, 361/45, 361/78, 361/71, 361/93.1, 361/93.2
• US Class Current: 361/42
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/04 with warning or supervision in addition to disconnection, e.g. for indicating that protective apparatus has functioned watching of pilot wires H02H1/0084; protection of protective arrangements H02H7/008; indication of the state of electronic switches H03K17/18

Abstract

A circuit breaker for shutting off an AC electrical source from a phase wire and a neutral wire has the ability to detect an arc fault, ground fault and overload. The circuit breaker includes an arc fault circuit interrupter (AFCI), a ground fault circuit interrupter (GFCI), an overload circuit interrupter (OLCI), and trip circuitry. The AFCI, the GFCI and the OLCI are crossed between the phase wire and the neutral wire of the AC power line and detect the arc fault, ground fault and overload respectively. The trip circuitry is used for shutting off the AC source from the circuit breaker when at least one of the arc fault, ground fault and overload occurs. The circuit breaker is shut when the level of at least one of an arc fault trip signal, ground fault trip signal and overload trip signal is larger than a specified reference trip level.

Claims

1. An arc fault circuit interrupter (AFCI) in an electrical wiring system that can shut an AC (Alternating Current) source off from a phase conductor and a neutral conductor when an arc fault occurs in the AC source, said AFCI comprising:

a current transformer for producing an arc voltage in accordance with the variation of current in the phase conductor and in the neutral conductor;

an arc fault detector for limiting the arc voltage to a specified level and producing an arc fault indicative signal when the arc voltage is higher than a reference arc signal with predetermined level;

a trip signal generator which is capable of charging the arc fault indicative signal, and if the charged arc fault indicative signal corresponds to a reference trip level, then producing a trip signal; and

a trip circuitry coupled to the phase conductor and the neutral conductor, for shutting the AC source off from the phase conductor and the neutral conductor in response to the trip signal

wherein said arc fault detector comprises;

a filter for diminishing a harmonic frequency (i.e., overtone) component from the arc voltage and limiting the arc voltage to a specified level; and

a comparator for comparing the limited arc voltage with the reference arc signal and producing the arc fault indicative signal when the limited arc voltage is larger than the reference arc signal;

wherein said filter comprises;

a level limiter for limiting the arc voltage to the specified level; and

a rectifier for half or full wave rectifying the limited arc voltage;

wherein said rectifier comprises;

a first plurality of diodes coupled between the resistor of said level limiter and ground; and

a second plurality of diodes coupled between the resistor of said level limiter and said comparator.

2. The AFCI as in claim 1, wherein said comparator comprises at least one operational amplifier.

3. The AFCI as in claim 1, wherein said comparator comprises a reference arc signal generator.

4. An arc fault circuit interrupter (AFCI) in an electrical wiring system that can shut an AC (Alternating Current) source off from a phase conductor and a neutral conductor when an arc fault occurs in the AC source, said AFCI comprising:

a current transformer for producing an arc voltage in accordance with the variation of current in the phase conductor and in the neutral conductor;

an arc fault detector for limiting the arc voltage to a specified level and producing an arc fault indicative signal when the arc voltage is higher than a reference arc signal with predetermined level;

a trip signal generator which is capable of charging the arc fault indicative signal, and if the charged arc fault indicative signal corresponds to a reference trip level, then producing a trip signal; and

a trip circuitry coupled to the phase conductor and the neutral conductor, for shutting the AC source off from the phase conductor and the neutral conductor in response to the trip signal;

wherein said trip signal generator comprises;

a voltage divider for dividing the arc fault indicative signal;

a comparator for comparing the divided arc fault indicative signal with the reference trip level and providing a first state output signal when the divided arc fault indicative signal is higher than the reference trip level;

a first switch for controlling electrical power being provided to the comparator; and

a trip level controller for providing the trip signal according to the first state output signal.

5. The AFCI as in claim 4, wherein said first switch comprises a common emitter amplifier.

6. The AFCI as in claim 4, wherein said trip level controller comprises a resistor coupled to output terminal of said comparator and a capacitor in parallel with the resistor.

7. The AFCI as in claim 6, wherein said resistor is a variable resistor.

8. The AFCI as in claim 4 further comprises a second switch coupled between said comparator and said trip level controller, for transferring the first state output signal to said trip level controller.

9. The AFCI as in claim 8, wherein said second switch comprises an emitter follower.

10. A circuit breaker in an electrical wiring system that can shut an AC (Alternating Current) source off from a phase conductor and a neutral conductor when at least one of an arc fault, ground fault or overload occurs in the AC source, said circuit breaker comprising:

an arc fault circuit interrupter (AFCI) coupled to the phase conductor and the neutral conductor for detecting an arc fault and producing an arc fault trip signal comprising;

a current transformer for producing an arc voltage in accordance with variation of current in the phase conductor and the neutral conductor;

an arc fault detector for limiting the arc voltage to a specified level and producing an arc fault indicative signal when the arc voltage is higher than a reference arc signal with predetermined level; and

a trip signal generator which is capable of charging the arc fault indicative signal, and if the charged arc fault indicative signal corresponds to a reference trip level, then producing the arc fault trip signal;

a ground fault circuit interrupter (GFCI) coupled to the phase conductor and the neutral conductor for detecting ground fault and producing a ground fault trip signal;

an overload circuit interrupter (OLCI) coupled to the phase conductor and the neutral conductor for detecting an overload and producing an overload trip signal;

a display circuitry for indicating the arc fault, ground fault or overload respectively corresponding with at least one selected from the group consisting of the arc fault trip signal, the ground fault trip signal and the overload trip signal; and

a trip circuitry coupled to the phase conductor and the neutral conductor, for shutting the AC source off from the phase conductor and the neutral conductor corresponding with at least one selected from the group consisting of the arc fault trip signal, the ground fault trip signal and the overload trip signal;

wherein said trip circuitry comprises;

a power interrupter for shutting the AC source off from the phase conductor and the neutral conductor if an arc fault, the ground fault or overload occurs; and

a trip controller for controlling said power interrupter corresponding with at least one selected from the group consisting of the arc fault trip signal, the ground fault trip signal and the overload trip signal;

wherein said trip controller comprises;

a silicon controlled rectifier (SCR);

at least one diode for directing path of the current flow in said trip circuitry in accordance with generation of the magnetic pulse; and

a pressure controller.

11. The circuit breaker as in claim 10, wherein said pressure controller comprises:

a first node coupled to the at least one diode of the trip controller and the varistor;

a second node coupled to the phase wire; and

a third node coupled to the first node,

wherein, the first node is connected to the second node or third node in accordance with an operation of said switch circuit.

12. The circuit breaker as in claim 10, wherein said display circuitry comprises:

a plurality of display elements for indicating at least one selected from the group consisting of the arc fault, the ground fault and the overload;

a display controller for controlling the operation of said display elements; and

a power supply for providing power to said display elements.

13. The circuit breaker as in claim 12, wherein said display elements comprise at least one light emitting diode.

14. The circuit breaker as in claim 12, wherein said display controller comprises a switching device connected between both ends of said display elements, wherein operation of the switching device is controlled by on/off of the circuit breaker.