Circuit breaker with arcing fault detection module

• US 5,818,671 A
• Filed: 10/04/1996
• Issued: 10/06/1998
• Est. Priority Date: 10/04/1996
• Status: Expired due to Term

• Current Assignee: General Electric Company
• Original Assignee: General Electric Company
• Inventors: Seymour, Raymond K., Kim, Edward E.
• Primary Examiner(s): Gaffin, Jeffrey A.
• Assistant Examiner(s): SHERRY, MICHAEL JUDE
• Application Number:
  US08/726,896
• Time in Patent Office: 732 Days
• Field of Search: 361/93-97, 361/99-100, 361/102-103, 361/105, 361/42, 361/43, 361/87, 361/45, 335/23-25, 335/31-32, 335/39-40, 335/43, 335/35, 335/201
• US Class Current: 361/42
• CPC Class Codes: H01H 2083/201 the other abnormal electrical condition being an arc fault
• CPC Class Codes: H02H 1/0015 Using arc detectors

Abstract

An arcing fault detecting module is attached to a circuit breaker employing a thermal-magnetic trip unit to separate the circuit breaker contacts upon occurrence of an arcing fault. The arcing fault module contains a logic circuit and a current transformer for detecting the arcing fault and actuating a trip solenoid to articulate the circuit breaker operating mechanism and separate the circuit breaker contacts.

Claims

1. An arcing fault module comprising:

a solenoid switch having a tripping armature;

a current sensing transformer for connecting with a protected circuit;

a conditioning circuit connecting with said current sensing transformer for providing an absolute value representation of arcing fault current within a protected circuit;

a threshold circuit connecting with said conditioning circuit for comparing said absolute value to a predetermined value;

an integrator circuit connecting with said threshold circuit for determining whether said arcing fault current persists greater than a predetermined time increment; and

an electronic switch connecting with said integrator circuit for producing a trip signal output when said arcing fault current persists greater than said predetermined time increment.

2. The arcing fault module of claim 1 wherein said current sensing transformer comprises an air core.

3. The arcing fault module of claim 1 wherein said conditioning circuit comprises a pair of amplifiers.

4. The arcing fault module of claim 1 wherein said threshold circuit comprises a first comparator.

5. The arcing fault module of claim 1 wherein said integrator circuit comprises a second comparator.

6. The arcing fault module of claim 1 wherein said electronic switch comprises an SCR.