ARC responsive thermal circuit breaker

• US 6,642,832 B2
• Filed: 10/29/2001
• Issued: 11/04/2003
• Est. Priority Date: 12/08/2000
• Status: Expired due to Fees

• Current Assignee: Sensata Technologies Massachusetts Incorporated (Sensata Technologies Holding Plc)
• Original Assignee: Texas Instruments, Inc.
• Inventors: Berg, Peter G., Pellon, Christian V.
• Primary Examiner(s): Vortman, Anatoly
• Application Number:
  US10/045,234
• Publication Number:
  US 20020080003A1
• Time in Patent Office: 736 Days
• Field of Search: 337/1-3, 337/12, 337/13, 337/35, 337/36, 337/37, 337/38, 337/55, 337/56, 337/66, 337/70-73, 337/75, 337/76, 337/90, 337/91, 361/1, 361/31, 361/32, 361/42, 361/62, 361/63, 361/78, 361/93.1, 361/102, 361/103, 361/105, 361/139
• US Class Current: 337/66
• CPC Class Codes: H01H 2083/201 the other abnormal electrical condition being an arc fault
• CPC Class Codes: H01H 71/04 Means for indicating condition of the switching device by means of an auxiliary contact H01H71/46
• CPC Class Codes: H01H 71/123 using a solid-state trip unit circuits H02H
• CPC Class Codes: H01H 71/127 using piezoelectric, electrostrictive or magnetostrictive trip units
• CPC Class Codes: H01H 73/306 the push-button supporting pivotally a combined contact-latch lever
• CPC Class Codes: H01H 83/20 operated by excess current as well as by some other abnormal electrical condition
• CPC Class Codes: H02H 1/0015 Using arc detectors

Abstract

A circuit breaker (10) has a current carrying bimetallic element (18) which bends upon self-heating and upon being subjected to a selected overload current transfers motion to a connecting plate (32) which displaces a latch surface (42b) from a catch (34a) of a bell crank mechanism (34) allowing a spring biased operating member (28) to move movable contact means (12) out of contact engagement with stationary contact means (14) thereby tripping the circuit breaker. An arc sensing circuit (52) is coupled to the load circuit and upon sensing selected arcs causes an arc responsive actuator (56, 62) to be energized to transfer motion to the latch (42) to trip the circuit breaker.

Claims

1. A circuit breaker comprising an electrically insulative housing, a stationary electrical contact mounted in the housing, a movable electrical contact mounted in the housing movable into and out of engagement with the stationary contact, a latch having a movably mounted latching surface, a contact opening mechanism connected to the movable contact and having a catch received on the latching surface, a spring biasing the contact opening mechanism toward a contact opening position with the engagement of the catch on the latch preventing such movement, a bimetallic element connected to the stationary contact to conduct current when the movable contact is in engagement with the stationary contact, the bimetallic element bending in a selected direction upon self-heating due to the conduction of current therethrough, a movable connecting plate extending from the bimetallic element to the latch, the bimetallic element bending sufficiently upon a current overload to move the connecting plate to in turn relatively move the latch from the catch to thereby trip the circuit breaker by allowing the contact opening mechanism to move the movable contact out of contact engagement with the stationary contact, an arc sensing circuit and an arc responsive actuator comprising a a solenoid mounted in the circuit breaker, the solenoid having a movable plunger and further comprising a pivotable trip lever having two opposite ends, one opposite end disposed adjacent to and in alignment with the plunger and the other opposite end of the trip lever connected to the connecting plate so that energizing of the solenoid will cause the plunger to transfer motion to the said one end of the trip lever causing it to pivot and in turn moving the connecting plate to trip the circuit breaker, the arc sensing circuit, upon sensing an arc in the circuit connected to the stationary and movable electrical contacts, causing the solenoid to be energized to move the latch relative to the catch and trip the circuit breaker.

2. A circuit breaker comprising an electrically insulative housing, a stationary electrical contact mounted in the housing, a movable electrical contact mounted in the housing movable into and out of engagement with the stationary contact, a latch having a movably mounted latching surface, a contact opening mechanism connected to the movable contact and having a catch received on the latching surface, a spring biasing the contact opening mechanism toward a contact opening position with the engagement of the catch on the latch preventing such movement, a bimetallic element connected to the stationary contact to conduct current when the movable contact is in engagement with the stationary contact, the bimetallic element bending in a selected direction upon self-heating due to the conduction of current therethrough, a movable connecting plate extending from the bimetallic element to the latch, the bimetallic element bending sufficiently upon a current overload to move the connecting plate to in turn relatively move the latch from the catch to thereby trip the circuit breaker by allowing the contact opening mechanism to move the movable contact out of contact engagement with the stationary contact, an arc sensing circuit and an arc responsive actuator comprising a a solenoid mounted in the circuit breaker, the solenoid having a movable plunger and further comprising a trip lever fixedly attached to the latch and having an end adjacent to and in alignment with the plunger so that energization of the solenoid will cause the plunger to transfer motion to the said end of the trip lever causing the latch to move to trip the circuit breaker, the arc sensing circuit, upon sensing an arc in the circuit connected to the stationary and movable electrical contacts, causing the solenoid to be energized to move the latch relative to the catch and trip the circuit breaker.

3. A circuit breaker comprising an electrically insulative housing, a stationary electrical contact mounted in the housing, a movable electrical contact mounted in the housing movable into and out of engagement with the stationary contact, a latch having a movably mounted latching surface, a contact opening mechanism connected to the movable contact and having a catch received on the latching surface, a spring biasing the contact opening mechanism toward a contact opening position with the engagement of the catch on the latch preventing such movement, a bimetallic element connected to the stationary contact to conduct current when the movable contact is in engagement with the stationary contact, the bimetallic element bending in a selected direction upon self-heating due to the conduction of current therethrough, a movable connecting plate extending from the bimetallic element to the latch, the bimetallic element bending sufficiently upon a current overload to move the connecting plate to in turn relatively move the latch from the catch to thereby trip the circuit breaker by allowing the contact opening mechanism to move the movable contact out of contact engagement with the stationary contact, an arc sensing circuit and an arc responsive actuator comprising a piezoresistive element mounted in the circuit breaker the piezoresistive element being elongated having an end connected to the connecting plate so that energization of the piezoresistive element will cause the said end of the piezoresistive element to bend transferring motion to the connecting plate to trip the circuit breaker, the arc sensing circuit, upon sensing an arc in the circuit connected to the stationary and movable electrical contacts, causing the piezoresistive element to be energized to move the latch relative to the catch and trip the circuit breaker.

4. A circuit breaker comprising an electrically insulative housing, a stationary electrical contact mounted in the housing, a movable electrical contact mounted in the housing movable into and out of engagement with the stationary contact, a latch having a movably mounted latching surface, a contact opening mechanism connected to the movable contact and having a catch received on the latching surface, a spring biasing the contact opening mechanism toward a contact opening position with the engagement of the catch on the latch preventing such movement, a bimetallic element connected to the stationary contact to conduct current when the movable contact is in engagement with the stationary contact, the bimetallic element bending in a selected direction upon self-heating due to the conduction of current therethrough, a movable connecting plate extending from the bimetallic element to the latch, the bimetallic element bending sufficiently upon a current overload to move the connecting plate to in turn relatively move the latch from the catch to thereby trip the circuit breaker by allowing the contact opening mechanism to move the movable contact out of contact engagement with the stationary contact, an arc sensing circuit and an arc responsive actuator comprising a piezoresistive element mounted in the circuit breaker the piezoresistive element being elongated having a free end and further comprising a trip lever fixedly attached to the latch, the free end of the piezoresistive element coupled to the trip lever so that energization of the piezoresistive element will cause the free end of the piezoresistive element to bend transferring motion to the trip lever to the trip the circuit breaker, the arc sensing circuit, upon sensing an arc in the circuit connected to the stationary and movable electrical contacts, causing the piezoresistive element to be energized to move the latch relative to the catch and trip the circuit breaker.