Electricity: measuring and testing – Electromechanical switching device – Circuit breaker
Reexamination Certificate
1999-11-05
2003-04-08
Le, N. (Department: 2858)
Electricity: measuring and testing
Electromechanical switching device
Circuit breaker
C324S537000, C324S546000, C324S547000
Reexamination Certificate
active
06545479
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates generally to the field of electronic circuit breakers and more specifically to the field of testers for electronic circuit breakers.
BACKGROUND OF THE INVENTION
An electronic circuit breaker is used to interrupt an electric circuit under an abnormal condition, such as a power surge or a ground fault. An electronic circuit breaker is rated at a predetermined amperage which indicates the threshold current passing through the breaker which will trip the breaker, causing it to interrupt the electric circuit. The tester of the present invention is particularly suited for testing circuit breakers having threshold current ratings of between 63 and 1600 Amperes, though the tester may find applications involving the testing of other circuit breakers as well.
Circuit breakers require regular testing by maintenance personnel to ensure they are functioning properly. Circuit breakers also sometimes require testing to troubleshoot breaker malfunctions. During routine maintenance or breaker troubleshooting, a tester is coupled to each circuit breaker to test the functionality of the circuit breaker. Problems are diagnosed based on the test, and the circuit breaker is repaired or replaced as needed.
Some present-day testers are large and unwieldy, typically comprising a suitcase-sized box (e.g., eighteen inches by twelve inches by six inches). These testers include a full-sized keyboard and display. These testers perform many tests on the circuit breakers, some of which may not be necessary to provide a reasonable diagnosis of the functionality of the circuit breaker. The size and complexity of these testers makes them difficult to use and transport in many applications, particularly when the maintenance personnel must travel to the work site.
One portable tester performs a “dry” test and a primary injection test. The dry test subjects the breaker to simulated phase overload and simulated ground fault tests. Primary injection testing verifies the wiring outside of the circuit breaker. However, both tests are not necessary for all testing situations. Also, this tester fails to test the continuity of the current transformer within the circuit breaker which, it has been found, yields a great deal of test data regarding the condition of a circuit breaker.
Accordingly, what is needed is a portable tester which performs the necessary test functions to provide a reasonably reliable diagnosis of the circuit breaker, yet is simple to use by minimally trained personnel. The portable tester would also test the continuity of the current transformer inside the circuit breaker. Furthermore, the portable tester would be able to trip a circuit breaker even when the tester is operating on battery power.
SUMMARY OF THE INVENTION
One embodiment of the invention relates to a circuit breaker tester for testing a current transformer of a circuit breaker, the current transformer having a first terminal on a first end of the transformer and a second terminal on a second end of the transformer. The circuit breaker tester comprises a test port configured to be coupled to the first and second terminals and a test circuit coupled to the test port and configured to provide a test current through the test port to the first terminal, to monitor the second terminal through the test port, and to provide an output signal to an indicia based on whether the test current is received at the second terminal.
According to another embodiment, a portable tester for testing a circuit breaker having an electronic module and a current transformer includes a housing configured to be held in a hand, a test port, and a test circuit. The test port is coupled to the housing and configured for coupling to the circuit breaker. The test circuit is coupled to the housing and the test port and is configured to perform first and second testing operations on the circuit breaker through the test port. During the first testing operation the test circuit provides a test signal to a terminal coupled to the current transformer and during the second testing operation the test circuit provides power to the electronic module of the circuit breaker.
According to yet another embodiment, a portable tester for performing an overcurrent test on a circuit breaker having an electronic module, a trip unit, and a current transformer is disclosed. The electronic module has an adjustable trip current and a rating. The portable tester includes a housing configured to be held in a hand, a battery terminal configured to be coupled to a battery, a test port coupled to the housing and configured for coupling to the circuit breaker, and a test circuit coupled to the housing, the battery, and the test port. The test circuit is configured to provide power to the electronic module of the circuit breaker and to provide a test current from the battery to the trip unit to perform an overcurrent test on the trip unit, wherein the test current has a magnitude less than the rating associated with the trip unit.
According to still another embodiment, a circuit breaker tester for testing a current transformer of a circuit breaker includes a means for providing a test current through the current transformer, a means for receiving the test current from the current transformer, and a means for providing an output signal to an indicia based on whether the test current is received at the means for receiving.
According to yet another embodiment, a portable circuit breaker tester for testing a circuit breaker having an electronic module and at least one current transformer consists of a means for testing the continuity of the at least one current transformer and a means for powering the electronic module and for performing an overcurrent test on the circuit breaker.
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Bilac Mario
Dollar, II Charles Randall
Green Jerry M.
Hamdan Wasseem H.
Le N.
Siemens Energy & Automation Inc.
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