Improved Magnetic Core Coupling in Current Transformers with Integrated Magnetic Actuators

Abstract

A system comprising a magnetic actuator, a current transformer and operational electronics in a dual-coil circuit breaker. The system includes an inline, but non concentric, implementation of the primary and secondary coils to maintain a narrow width suitable for retrofitting in standard industrial rack mounted enclosures. The system further comprises an I-shaped lamination stack that is designed to abut on the ends of an upper and lower plate of the current transformer. The I-shaped lamination stack significantly increases the overlap between the lamination and the upper and lower plates, which results in lower magnetic reluctance and improves magnetic coupling.

Description

[0001] Cross reference to related applications [0002] This application is part of U.S. application No. 12 / 762,894 filed on April 19, 2010 under the title "Current Transformer with Integrated Actuator" and U.S. Application No. 61 / 176,677 filed on May 8, 2009 The continuation of the application, in which the U.S. application No. 12 / 762,894 requests priority of the European application No. 10158680.8 filed on March 26, 2010. The entirety of each of the aforementioned applications is incorporated herein by reference. Technical field [0003] The invention relates to industrial control systems, and more particularly to systems and methods that provide improved magnetic core coupling in current transformers with integrated magnetic actuators. Background technique [0004] Typical current motor protection circuit breakers for rated currents up to approximately 100 amps are designed with bimetallic strips / heaters for thermal protection and magnetic plungers for short circuit protection. ...

AI Technical Summary

Problems solved by technology

[0005] Another disadvantage in the design of this traditional circuit breaker is the lack of integrated electronics for measuring the state of the circuit breaker and the ability to communicate this data to a control system or network

Because the first signs of a problem with the circuit breaker follow a circuit breaker failure, opportunities for greater operational efficiency and preventive maintenance are lost

In addition, high form factors with respect to design operating characteristics in such circuit breakers, such as speed of contact opening, prevention of reclosing, and / or prevention of welding, lead to higher manufacturing costs

Additionally, such conventional circuit breaker designs have large size

Furthermore, in conventional designs, excess magnetic flux is shunted away, which results in high levels of breaker tripping current and seriously compromises the tripping function of the circuit breaker

Also, poor magnetic coupling can lead to low conversion efficiency, low secondary output current and / or loss of current measurement linearity

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