Arc fault circuit interrupter

• US 7,362,552 B2
• Filed: 07/20/2004
• Issued: 04/22/2008
• Est. Priority Date: 07/20/2004
• Status: Active Grant

• Current Assignee: Eaton Intelligent Power Limited (Eaton Corporation PLC.)
• Original Assignee: Eaton Corp. (Wisconsin) (Eaton Corporation PLC.)
• Inventors: Elms, Robert T., Parker, Kevin L., Zuercher, Joseph C.
• Primary Examiner(s): Sherry; Michael
• Assistant Examiner(s): THOMAS, LUCY M
• Application Number:
  US10/895,158
• Publication Number:
  US 20060018060A1
• Time in Patent Office: 1,372 Days
• Field of Search: 361/42, 361/44
• US Class Current: 361/42
• CPC Class Codes: H02H 1/0015 Using arc detectors
• CPC Class Codes: H02H 3/05 with means for increasing reliability, e.g. redundancy arrangements for logic circuits H03K19/003
• CPC Class Codes: H02H 3/33 using summation current transformers H02H3/347 takes precedence

Abstract

An arc fault circuit interrupter includes line and load terminals, separable contacts, a current sensor sensing current flowing between the terminals and associated with one type of load, and a first arc fault detection circuit generating a first trip signal responsive to the sensed current. A second arc fault detection circuit collects a plurality of sensed current samples for a current line cycle and also for a previous line cycle, determines a total current value from a peak current of the current line cycle samples, employs the total current value and some of the samples to determine the type of load, and generates a second trip signal responsive to the sensed current and the determined type of load. A trip circuit generates a third trip signal responsive to the first and second trip signals. An operating mechanism opens the contacts responsive to the third signal.

Claims

1. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit includes a trip tally value; and

wherein said second arc fault detection circuit clears said trip tally value when said peak current is greater than a first predetermined value; and

wherein said line cycles correspond to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage;

wherein a current value is the larger of a fraction of said peak current and a second predetermined value;

wherein said second arc fault detection circuit decrements said nip tally value when;

(a) all of said samples of said sensed current for the current one of said line cycles are less than or equal to a third predetermined value;

(b) the sixteenth or the seventeenth samples of said sensed current for the current one of said line cycles are greater than or equal to said current value;

(c) the fourteenth or the fifteenth samples of said sensed current for the current one of said line cycles are less than or equal to said current value;

(d) the second sample of said sensed current for the current one of said line cycles is greater than or equal to a fraction of said current value;

or (e) the difference of the eighth sample less the tenth sample of said sensed current for the current one of said line cycles is greater than or equal to a fraction of said current value.

2. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit includes a trip tally value; and

wherein said second arc fault detection circuit clears said trip tally value when said peak current is greater than a first predetermined value; and

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage;

wherein a current value is the larger of a fraction of said peak current and a second predetermined value;

wherein said second arc fault detection circuit increases said trip tally value by the largest one of said samples of said sensed current for the current one of said line cycles when;

(a) any of said samples of said sensed current for the current one of said line cycles is greater than a third predetermined value;

(b) the sixteenth or the seventeenth samples of said sensed current for the current one of said line cycles are less than said current value;

(c) the fourteenth or the fifteenth samples of said sensed current for the current one of said line cycles are greater than said current value;

(d) the second sample of said sensed current for the current one of said line cycles is less than a fraction of said current value; and

(e) the difference of the eighth sample less the tenth sample of said sensed current for the current one of said line cycles is less than a fraction of said current value.

3. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit includes a trip tally value; and

wherein said second arc fault detection circuit clears said trip tally value when said peak current is greater than a first predetermined value; and

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and another one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein said second arc fault detection circuit determines whether there is an arc and responsively increases said trip tally value by the largest one of said samples of said sensed current for the current one of said line cycles and, otherwise, decrements said trip tally.

4. The arc fault circuit interrupter of claim 3 wherein said second arc fault detection circuit generates said second trip signal when said trip tally is greater than a second predetermined value.

5. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit includes a trip tally value; and

wherein said second arc fault detection circuit clears said trip tally value when said peak current is greater than a first predetermined value; and

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage;

wherein a current value is the larger of a fraction of said peak current and a second predetermined value;

wherein said second arc fault detection circuit increases said trip tally value by the largest one of said samples of said sensed current for the current one of said line cycles when;

(a) any of said samples of said sensed current for the current one of said line cycles is greater than a third predetermined value;

(b) the sixteenth sample of said sensed current for the current one of said line cycles is less than said current value;

(c) the twelfth sample of said sensed current for the current one of said line cycles is greater than a fraction of the largest one of said samples of said sensed current for the current one of said line cycles; and

(d) the second sample of said sensed current for the current one of said line cycles is less than said current value.

6. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit includes a trip tally value; and

wherein said second arc fault detection circuit clears said trip tally value when said peak current is greater than a first predetermined value; and

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage;

wherein a current value is the larger of a fraction of said peak current and a second predetermined value;

wherein said second arc fault detection circuit increases said trip tally value by the largest one of said samples of said sensed current for the current one of said line cycles when;

(a) any of said samples of said sensed current for the current one of said line cycles is greater than a third predetermined value;

(b) the fifteenth sample of said sensed current for the current one of said line cycles is less than said current value;

(c) the twelfth sample of said sensed current for the current one of said line cycles is greater than a fraction of the largest one of said samples of said sensed current for the current one of said line cycles; and

(d) the third sample of said sensed current for the current one of said line cycles is less than said current value.

7. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal; and

wherein said line cycle corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage;

wherein said second arc fault detection circuit collects and saves said samples of said sensed current for four consecutive ones of said line cycles;

wherein for three consecutive ones of said line cycles said second arc fault detection circuit determines differences between each of the samples of one of the line cycles and each of the samples of an immediately previous one of the line cycles and determines a maximum positive value and a maximum negative value from said differences for said three consecutive ones of said line cycles;

wherein said second arc fault detection circuit determines whether there is one or both of a local maximum value and a local minimum value from said determined maximum positive value and said determined maximum negative value over said three consecutive ones of said line cycles;

wherein said second arc fault detection circuit determines a hysteresis value based upon said one or both of said local maximum value and said local minimum value for the current one of said line cycles; and

wherein said second arc fault detection circuit determines if said local maximum value or said local minimum value is greater than said hysteresis value and responsively adds said total current value to a trip tally.

8. The arc fault circuit interrupter of claim 7 wherein said second arc fault detection circuit employs a predetermined value for said hysteresis value.

9. The arc fault circuit interrupter of claim 7 wherein said second arc fault detection circuit is adapted to clear said trip tally when said total current value is greater than a predetermined value.

10. The arc fault circuit interrupter of claim 7 wherein said second arc fault detection circuit includes an enable counter and a disable counter;

and wherein when said total current value is greater than a first predetermined value said enable counter is incremented and said disable counter is zeroed.

11. The arc fault circuit interrupter of claim 10 wherein said second arc fault detection circuit further includes a flag having an enable state and a disable state;

wherein said enable counter includes a first limit;

wherein said disable counter includes a second limit;

wherein said flag is set to said enable state when said enable counter exceeds said first limit; and

wherein said flag is set to said disable state when said disable counter exceeds said second limit.

12. The arc fault circuit interrupter of claim 11 wherein when said second arc fault detection circuit determines if said maximum value or said minimum value is greater than said hysteresis value and responsively adds said total current value to a trip tally, and when said flag has said disable state, said trip tally is cleared, and, alternatively, when said flag has said enable state, and when said trip tally is greater than a second predetermined value, said second trip signal is generated.

13. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit compares at least one of said samples of said sensed current for the current one of said line cycles to a predetermined fraction of said total current value and compares said total current value to a predetermined value, in order to determine said one of said types of loads; and

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein a twelfth sample of said sensed current for the current one of said line cycles is less than about half of said total current value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a computer.

14. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of Line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit compares at least one of said samples of said sensed current for the current one of said line cycles to a predetermined fraction of said total current value and compares said total current value to a predetermined value, in order to determine said one of said types of loads; and

wherein said second arc huh detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said predetermined value is a first predetermined value;

wherein said samples of said sensed current for a current one of said line cycles include a plurality of unfiltered samples and a plurality of filtered samples;

wherein a seventeenth unfiltered sample of said sensed current for the current one of said line cycles is greater than said first predetermined value;

wherein a fifth filtered sample of said sensed current for the current one of said line cycles is greater than about one eight of said total current value;

wherein said total current value is greater than a second predetermined value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a vacuum cleaner.

15. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit compares at least one of said samples of said sensed current for the current one of said line cycles to a predetermined fraction of said total current value and compares said total current value to a predetermined value, in order to determine said one of said types of loads; and

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said samples of said sensed current for a current one of said line cycles include a plurality of unfiltered samples and a plurality of filtered samples;

wherein a fifth filtered sample of said sensed current for the current one of said line cycles is greater than about one half of said total current value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a fluorescent bulb.

16. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of load, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit compares at least one of said samples of said sensed current for the current one of said line cycles to a predetermined fraction of said total current value and compares said total current value to a predetermined value, in order to determine said one of said types of loads; and

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said samples of said sensed current for a current one of said line cycles include a plurality of unfiltered samples and a plurality of filtered samples;

wherein said predetermined value is a first predetermined value;

wherein a seventeenth filtered sample of said sensed current for the current one of said line cycles is greater than about one fourth of said total current value or greater than said first predetermined value;

wherein said total current value is greater than a second predetermined value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a compressor.

17. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein said second arc fault detection circuit responds to changes in said sensed current as a function of time; and

wherein said second arc fault detection circuit determines a trip tally based upon said changes in said sensed current as a function of time;

wherein said seventeenth one of said samples is greater than a fraction of said total current value; and

wherein said second arc fault detection circuit increases said trip tally value by said total current value plus one.

18. The arc fault circuit interrupter of claim 17 wherein said second arc fault detection circuit generates said second trip signal when said trip tally is greater than a first predetermined value and, otherwise, decrements said trip tally.

19. The arc fault circuit interrupter of claim 18 wherein said second arc fault detection circuit generates said second trip signal when said trip tally is greater than a second predetermined value and, otherwise, decrements said trip tally.

20. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said current one of said line cries corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein said second arc fault detection circuit responds to changes in said sensed current as a function of time; and

wherein said second arc fault detection circuit determines a trip tally based upon said changes in said sensed current as a function of time;

wherein said seventeenth sample less a sixteenth sample plus an eighteenth sample less said seventeenth sample is greater than two times a difference between a sixteenth sample less a fifteenth sample plus six; and

wherein said second arc fault detection circuit increases said trip tally value by said total current value plus one.

21. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said lime cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing; and

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein said seventeenth one of said samples of said sensed current is greater than or equal to a predetermined value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a compressor or a vacuum cleaner.

22. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current fir a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing; and

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein a thirteenth one of said samples of said sensed current is less tan or equal to a predetermined value; and

wherein said second arc fault detection circuit responsively determines tat said determined one of said types of loads is a computer.

23. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing; and

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein a maximum value of said samples of said sensed current is less than or equal to a predetermined value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a drill.

24. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second trip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current for the current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing; and

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein said seventeenth one of said samples of said sensed current is less tan a first predetermined value;

wherein a thirteenth one of said samples of said sensed current is greater than a second predetermined value;

wherein a maximum value of said samples of said sensed current is greater than a third predetermined value;

wherein a fifth one of said samples of said sensed current is greater than a fourth predetermined value; and

wherein for each of said fifth one of said samples of said sensed current through and including an eleventh one of said samples of said sensed current, a difference between (a) a second one of said samples after said each of said fifth one of said samples of said sensed current through and including an eleventh one of said samples of said sensed current and (b) said each of said fifth one of said samples of said sensed current through and including an eleventh one of said samples of said sensed current is greater than a fifth predetermined value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a dimmer.

25. An arc fault circuit interrupter for an electrical circuit associated with one of a plurality of different types of loads, said arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said current associated with one of said types of loads, said sensed current including a plurality of line cycles;

a first arc fault detection circuit adapted to generate a first trip signal responsive to said sensed current from said current sensor;

a second arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, to employ only a plurality of constant values, said total current value and some of said samples to determine said one of said types of loads, and to generate a second trip signal responsive to said sensed current from said current sensor and said determined one of said types of loads;

a trip circuit adapted to generate a third trip signal responsive to said first trip signal or said second flip signal;

an operating mechanism adapted to open said separable contacts responsive to said third trip signal;

wherein said second arc fault detection circuit collects about 19 of said samples of said sensed current forte current one of said line cycles at a rate of about 32 samples per line cycle;

wherein said current one of said line cycles corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing; and

wherein said second arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero, crossing of the line cycle of said line voltage and a seventeenth one of said samples of said sensed current at about the negative zero crossing of the line cycle of said line voltage; and

wherein said seventeenth one of said samples of said sensed current is less than a first predetermined value;

wherein a thirteenth one of said samples of said sensed current is greater than a second predetermined value;

wherein a maximum value of said samples of said sensed current is greater than a third predetermined value;

wherein a fifth one of said samples of said sensed current is greater than a fourth predetermined value; and

wherein for each of said fifth one of said samples of said sensed current though and including an eleventh one of said samples of said sensed current, a difference between (a) a second one of said samples after said each of said fifth one of said samples of said sensed current through and including an eleventh one of said samples of said sensed current and said each of said fifth one of said samples of said sensed current through and (b) including an eleventh one of said samples of said sensed current is less than or equal to a fifth predetermined value; and

wherein said second arc fault detection circuit responsively determines that said determined one of said types of loads is a drill or a fluorescent bulb.

26. An arc fault circuit interrupter comprising:

a line terminal;

a load terminal;

separable contacts electrically connected between said line terminal and said load terminal;

a current sensor adapted to sense current flowing between said line terminal and said load terminal and through said separable contacts, said sensed current including a plurality of line cycles;

an arc fault detection circuit adapted to collect a plurality of samples of said sensed current for a current one of said line cycles and a plurality of samples of said sensed current for one of said line cycles prior to said current one of said line cycles, to determine a total current value from a peak current of said samples of said sensed current for the current one of said line cycles, and to generate a trip signal responsive to said sensed current from said current sensor; and

an operating mechanism adapted to open said separable contacts responsive to said trip signal,

wherein said line cycle corresponds to a line voltage having a line cycle with a positive zero crossing and a negative zero crossing;

wherein said arc fault detection circuit collects a first one of said samples of said sensed current at about the positive zero crossing of the line cycle of said line voltage and an Nth one of said samples of said sensed current at about the negative zero crossing of the line cycle&

of said line voltage;

wherein said arc fault detection circuit collects and saves said samples of said sensed current for four consecutive ones of said line cycles;

wherein for three consecutive ones of said line cycles said arc fault detection circuit determines differences between each of the samples of one of the line cycles and each of the samples of an immediately previous one of the line cycles and determines a maximum positive value and a maximum negative value from said differences for said three consecutive ones of said line cycles;

wherein said arc fault detection circuit determines whether there is one or both of a local maximum value and a local minimum value from said determined maximum positive value and said determined maximum negative value over said three consecutive ones of said line cycles;

wherein said arc fault detection circuit determines a hysteresis value based upon said one or both of said local maximum value and said local minimum value for the current one of said line cycles; and

wherein said arc fault detection circuit determines if said local maximum value or said local minimum value is greater than said hysteresis value and responsively adds said total current value to a trip tally for said trip signal.