Microcomputer-controlled circuit breaker system

• US 5,166,887 A
• Filed: 01/28/1991
• Issued: 11/24/1992
• Est. Priority Date: 03/31/1988
• Status: Expired due to Term

• Current Assignee: Square D Company (Schneider Electric SE)
• Original Assignee: Square D Company (Schneider Electric SE)
• Inventors: Farrington, Ronald L., Porter, Thomas W.
• Primary Examiner(s): Teska, Kevin J.
• Application Number:
  US07/624,011
• Time in Patent Office: 666 Days
• Field of Search: 361/48, 361/71, 361/94, 361/95, 361/96, 361/105, 364/480, 364/481, 364/483, 364/492
• US Class Current: 700/293
• CPC Class Codes: H01H 2071/006 Provisions for user interfaces for electrical protection devices
• CPC Class Codes: H01H 2300/03 Application domotique, e.g. for house automation, bus connected switches, sensors, loads or intelligent wiring
• CPC Class Codes: H02H 3/00 Emergency protective circuit arrangements for automatic disconnection directly responsive to an undesired change from normal electric working condition with or without subsequent reconnection specially adapted for specific types of electric machines or apparatus or for sectionalised protection of cable or line systems H02H7/00; systems for change-over to standby supply H02J9/00 ; integrated protection for motors H02H7/0822
• 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
• CPC Class Codes: Y02B 70/30 Systems integrating technologies related to power network operation and communication or information technologies for improving the carbon footprint of the management of residential or tertiary loads, i.e. smart grids as climate change mitigation technology in the buildings sector, including also the last stages of power distribution and the control, monitoring or operating management systems at local level
• CPC Class Codes: Y02B 90/20 Smart grids as enabling technology in buildings sector smart grids supporting the management or operation of end-user stationary applications in general, or like technologies with no associated climate change mitigation effect Y04S20/00
• CPC Class Codes: Y04S 20/14 Protecting elements, switches, relays or circuit breakers
• CPC Class Codes: Y04S 20/20 End-user application control systems

Abstract

A circuit breaker system employs a sensor circuit to measure the current flow in a conductor. A microcomputer monitors the current flow and trips a circuit breaker if the measured current flow exhibits certain predetermined characteristics. A power supply circuit generates a regulated output voltage proportional to the measured current flow to supply power to a portion of the circuit breaker system electronics. To protect the portion of the electronics powered by the power supply circuit, the output from the power supply is shorted through a resistance circuit for a predetermined period of time if the magnitude of the measured current flow induces an output voltage in excess of a predetermined level.

Claims

1. An improved circuit breaker system for interrupting an electric current flow through at least one conductor from a source of electric energy to a load comprising:

a sensor circuit which measures current flow in said at least one conductor and for generating a signal corresponding to the magnitude of said current flow;

a circuit breaker having a microcomputer associated therewith, said microcomputer including means for receiving said signal and for calculating at least one quantity responsive to said signal, said microcomputer including means for comparing said at least one quantity with at least one predetermined limit value, said microcomputer comprising means for disconnecting said load from said source by tripping said circuit breaker if said at least one quantity differs from said at least one predetermined limit value by at least a predetermined difference;

a power supply circuit, coupled to said at least one conductor, for providing a secondary electric current flow proportional to said current flow in said at least one conductor, said power supply circuit including means for generating an output voltage proportional to said secondary electric current flow;

means for connecting said output voltage to at least part of said circuit breaker to provide operating power to said at least part of said circuit breaker;

a resistance circuit electrically associated with said power supply circuit; and

means, responsive to the magnitude of current flow in said at least one conductor, for coupling said output voltage to said resistance circuit for a predetermined time interval to protect said at least part of said circuit breaker from an overvoltage condition arising if said output voltage exceeds an acceptable level.

2. An improved circuit breaker system as in claim 1 wherein said means for coupling said regulated output voltage to said resistance circuit includes a relaxation oscillator having a predetermined relaxation time period.