Electricity: electrical systems and devices – Safety and protection of systems and devices – With specific circuit breaker or control structure
Reexamination Certificate
1999-10-26
2001-09-25
Jackson, Stephen W. (Department: 2836)
Electricity: electrical systems and devices
Safety and protection of systems and devices
With specific circuit breaker or control structure
C361S093100, C361S096000
Reexamination Certificate
active
06295190
ABSTRACT:
BACKGROUND OF INVENTION
This invention relates to circuit breaker arrangements which provide electrical protection, control and monitoring functions for medium voltage electrical power generation and delivery systems. In particular, this invention relates to circuit breaker arrangements that integrate and enhance the protection, control and monitoring functions required for electrical power generation and delivery systems.
Various prior art protection, control and monitoring disclosures describe concepts for achieving more enhanced and/or integrated protection, control and monitoring (PCM) for power delivery systems.
For example, the Mauthe U.S. Pat. No. 4,742,197 discloses a high voltage gas-insulated circuit interrupter which utilizes Rogowski coils to measure current at both ends of the interrupter. That patent describes a high voltage switch to which current measuring heads can be fitted by a simple arrangement in an easily accessible manner outside the region of the interrupter chamber. A Rogowski coil may be used in the measuring head and such measuring heads may be applied to high voltage circuit breakers and other switchgear.
The Baumgartner et al. U.S. Pat. No. 5,272,460 discloses a current and voltage transformer for a metal-encapsulated, gas-insulated high voltage switching installation having small dimensions capable of incorporation without problems at any point in the installation. A Rogowski coil is used for current measurement.
The Oishi et al. U.S. Pat. No. 4,237,520 discloses a gas-insulated switchgear arrangement which enables reduction of floor space for mounting and which is easy to install, maintain and inspect.
The Puccinelli et al. U.S. Pat. No. 4,644,438 discloses a current-limiting circuit breaker having a selective solid state trip unit providing circuit breaker contact separation by electro-dynamic repulsion toward the open position to effect current limiting when fault current exceeds a predetermined threshold. Rogowski coils may be used for fault current detection.
The Fernandez U.S. Pat. No. 4,799,005 discloses an electrical power line parameter measurement arrangement including compact, line-mounted modules. Current sensing provided by Rogowski coils is used for control and monitoring as well as in protection arrangements including bus and transformer differential. Relay systems actuated by the sensors operate circuit breakers to provide fault protection.
The Moncorge U.S. Pat. No. 5,552,978 discloses an arrangement for supplying a voltage to an electronic circuit, in particular an electronic circuit associated with a current sensor disposed on a high tension electrical line, to derive power from the current that passes through the high tension line. The power supply uses a torus provided with a magnetic core and a secondary winding to extract power from the line. A Rogowski coil is used to measure the line current.
The Blakely U.S. Pat. No. 5,652,507 discloses an arrangement and a method for measuring an AC current which saturates the core of a current transformer.
None of the prior art provides an arrangement for integrating protection, control and monitoring functions directly into a medium voltage circuit breaker design
SUMMARY OF THE INVENTION
Accordingly, it is an object of the present invention to provide a PCM module arrangement which includes a medium voltage circuit breaker with integrated protection, control and monitoring (PCM) components, such as a PCM electronics unit, sensors and multiple interface connections, which overcomes disadvantages of the prior art.
Another object of the invention is to provide a PCM module arrangement which integrates protection, control, and monitoring features of the arrangement into a standard configurable PCM electronics unit, integrates current sensing devices into the PCM module's circuit breaker and provides a direct interface at the PCM module's electronics unit to input multiple sensed parameters.
A further object of the invention is to provide a PCM module arrangement which selectively locates a phase fault or a sensitive ground fault on electrical generation and distribution systems, characterized by embodying distributed architectures, i.e., looped interconnections or zonal interconnections with multiple switchboards connected in series with multiple tie cables, interconnection of switchboards or generators connected to different switchboards, and having a high impedance system ground.
An additional object of the invention is to provide a PCM module which includes optimized sensors as part of the PCM module to assure a maximum degree of sensitivity for the detection of phase currents and zero sequence currents.
These and other objects of the invention are attained by providing a PCM module arrangement which includes a medium voltage circuit breaker arrangement having Rogowski coil current sensors at both the line side and the load side in each phase of the circuit breaker, along with a zero sequence current sensor enclosing all of the circuit breaker load lines for sensing ground current, and a PCM electronics unit including multiple-interface connections.
With this arrangement, various configurations of PCM functions can be provided by the PCM module so that a single PCM module design can be applied to various types of equipment and apparatus, such as generators, transformers, bus ties, motors and switchboard-bus protection, to provide the different PCM functions normally required for each type of equipment without the need for multiple discrete PCM logic devices and associated sensors.
An arrangement of this type provides an increased sensitivity, i.e., ability to obtain lower minimum pickup settings by using the Rogowski coil phase current sensors and the zero sequence current sensor.
In a particular embodiment of the invention, a PCM module includes an integrated combination of a medium voltage circuit breaker capable of operation over a wide range of voltages and frequencies with integrated line and load phase current sensing, a load side zero sequence current sensing signal interface, line and load side voltage sensing signal interfaces, a supervisory control and data acquisition interface, an interface for remote end differential current signals and an integrated, multifunction, configurable PCM electronics unit. The integrated multifunction PCM electronics unit, in conjunction with the electronic interfaces, provides multiple protection, control and monitoring functions that are configurable to achieve the functions required for specific applications. The PCM module provides a circuit breaker and PCM electronics unit that is configurable to provide either dedicated generator protection, control and monitoring, dedicated bus tic protection, control and monitoring, dedicated transformer protection, control and monitoring, or dedicated motor protection, control and monitoring, and the PCM modules are capable of joint configuration to provide bus protection.
Preferably, all the logic required to accomplish these functions is integrated into the PCM electronics unit of the PCM module and the PCM electronics unit operates in conjunction with the supervisory control and data acquisition system to coordinate PCM functions with the overall electric plant.
This allows PCM functions to be optimized for the type of equipment to be protected, i.e., generators, transformers, bus ties, feeders, motors, and switchboards or buses. It also allows selectively locating both phase faults and sensitive ground faults on distribution systems requiring distributed architectures, flexible operation and restricted design ground fault currents. Thus, the invention provides a PCM module arrangement that, together with a supervisory control and data acquisition system interface, is highly integrated and configurable so that it can satisfy all the normal protection, control and monitoring requirements that are different for each specific application of the circuit breaker. Each application is dependent on the various types of equipment normally encountered in a medium voltage generation and distribution
Kasson Matthew L.
Rinaldi Peter
Baker & Botts L.L.P.
Electric Boat Corporation
Jackson Stephen W.
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