Data retention in a circuit breaker

Details Data retention in a circuit breaker Data retention in a circuit breaker

1999-03-29

2001-05-15

Sherry, Michael J. (Department: 2836)

Electricity: electrical systems and devices

Safety and protection of systems and devices

With specific quantity comparison means

C361S092000, C361S079000

Reexamination Certificate

active

06233128

ABSTRACT:

TECHNICAL FIELD OF THE INVENTION
The present invention pertains in general to electronically controlled circuit breakers and, more particularly, to circuit breakers capable of retaining measured data obtained during operation in a power distribution network.
BACKGROUND OF THE INVENTION
In a typical AC power distribution system in a residential or a small business building, an array of electromechanical circuit breakers protects various branch circuits of the electrical wiring. Such circuit breakers utilize a thermally operated switch which, upon reaching a predetermined temperature due to excessive current passing therethrough, will “trip” and open the circuit connected to the switch.
Improved circuit breakers providing very rapid trip response and the ability to monitor circuit conditions and store data related thereto are disclosed in U.S. Pat. No. 4,949,214, entitled “TRIP DELAY OVERRIDE FOR ELECTRICAL CIRCUIT BREAKERS” issued to George A. Spencer on Aug. 14, 1990, an assignee of the present U.S. patent application, and in U.S. Pat. No. 5,875,087 entitled “CIRCUIT BREAKERS WITH INTEGRATED CONTROL FEATURES”, issued to Spencer, et al. and assigned to the assignee of the present application, which patents are incorporated herein by reference. The improved circuit breakers disclosed therein include an array of trip profiles tailored to the current draw characteristics of the various kinds of devices which may be connected to the AC power line branch circuit protected by the circuit breaker. These trip profiles, which are dynamically changeable, determine the current versus time configuration of the particular circuit breaker. Such improved circuit breakers overcome the principal disadvantages of the conventional thermally operated circuit breakers, including, for example, slow response time, inability of responding to differing in-rush current characteristics, inability of opening a circuit upon the occurrence of arcing (a potentially serious fire hazard), inadequate response to electrical stalling of motors connected to a protected line, etc.
Although the circuit breakers with trip delay override and the electronically controlled circuit breakers with integrated control features referenced above offer superior trip performance under a variety of load fault conditions, neither of the aforementioned advanced circuit breakers has the capability of storing substantial quantities of important system data obtained by the circuit breaker while monitoring the protected circuit, even for short interruptions of power.
Thus, there is a need for means to save the critical data in an electronic circuit breaker when the input power supply departs from normal specifications, in whatever degree and for whatever reason.
SUMMARY OF THE INVENTION
The present invention disclosed and claimed herein comprises an apparatus and method and for retaining parameter information generated or received in an electronic circuit breaker in the event of momentary or extended power interruptions. The electronic circuit breaker having a controller is connected in a branch circuit coupled to a power source via a power line and powered by the power source. Upon occurence of a power interruption or fault, the electronic circuit breaker includes means for generating a control signal responsive to the power fault; means for coupling the control signal to a control input of the circuit breaker and means for storing, responsive to the control signal, parameter information generated in or received by the electronic circuit breaker. The means for generating the control signal includes means for monitoring the power signal, comparing the power signal with a reference signal and means for outputting a control signal when the power signal falls below the reference signal. Data representing parameter information may be retained by charging a storage capacitor to the value corresponding to the parameter information being retained, by writing the parameter information being retained to an EEPROM or by writing the data containing the parameter information being retained into a Static RAM. Power signals that can be monitored to provide an early warning of the power interruption or fault to the circuit breaker and initiate the retention of data include sensing the AC voltage input to the branch circuit in which the circuit breaker is connected, sensing the unregulated DC voltage in the power supply that powers the circuit breaker and sensing the charging current of a filter capacitor in the power supply of the circuit breaker.


REFERENCES:
patent: 4827149 (1989-05-01), Yabe
patent: 4949214 (1990-08-01), Spencer
patent: 5384747 (1995-01-01), Clohset
patent: 5875087 (1999-02-01), Spencer et al.

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