Matsushita Electric Works, Ltd.

Kiyoshi Goto

Riichi Uotome

Takehiko Toguchi

Ritsu Yamamoto

Toshiyuki Suzuki

Takaaki Chuzawa

Hideya Kondo

Yoichi Yokoyama

Mamoru Tateno

Yoshihisa Ishigami

Yoichi Kunimoto

Hirofumi Fukazawa

A ground fault interrupter including a zero-phase current transformer configured to detect unbalanced current flowing in electric lines. A switch is provided in the electric lines. A detection resistor is connected in parallel to the zero-phase current transformer and configured to convert current outputted from the zero-phase current transformer to voltage. A controller is configured to determine based on the voltage of the detection resistor whether an electric leak occurs and to open the switch when the controller determines that an electric leak occurs. At least one filter is provided between the detection resistor and the controller and is configured to remove high frequency elements in the voltage of the resistor. The at least one filter includes an input side resistor connected in series to the controller and configured to limit current input to the controller; and a capacitor connected in parallel to the controller.

Ground fault interrupter

A sealed switch has a vessel defining therein a hermetically sealed space which receives a pair of fixed contacts and a movable contact bridging the fixed contact. The movable contact is movable between an ON-position of closing with the fixed contact and an OFF-position of separating from the fixed contacts. Hydrogen gas or hydrogen rich gas is filled in the sealed space in order to suppress arc development between the movable and fixed contacts. The plunger carries at its axial one end the movable contact and carrying at the other axial end an actuator which moves the plunger axially for movement of the movable contact from the OFF-position to the ON-position. An over-travel spring is provided to give a bias for moving the movable contact relative to the plunger in order to develop a contacting pressure between the movable and fixed contacts. The over-travel spring is supported to a spring holder secured to the plunger. The plunger is formed with a threaded portion which extends through the actuator to allow the plunger to move axially relative to the actuator for adjustment of a contact gap between the movable and fixed contact, and the spring holder is formed with stopper protrusions which project in abuttable and slidable relation to the interior surface of the vessel such that the movable contact is prevented from rotating together with the plunger. Accordingly, the spring holder is best utilized to restrict the movable contact from rotating together with the actuator to enable an easy adjustment of the contact gap simply by rotating the actuator.

Sealed contact device with contact gap adjustment capability

A sealed contact unit that attains stabilized contact switching operation and effective dimensional minimization with an arrangement wherein a switching contact section including opposing movable and stationary contacting members is housed within a sealed container together with an electrically insulating gas, a movable shaft interlocked to the movable contacting member is hermetically passed through a wall of the container to be axially shiftable with an end projected externally while the movable contacting member biased away from the stationary contacting member by a resetting spring is mounted through a contact-pressure spring to the other end of the movable shaft inside the container, the contact-pressure spring being provided to coaxially enclose the movable shaft and biasing the movable contacting member against the biasing force of the resetting spring for attaining a contact-pressure when the movable contact member shifts to engage the stationary contact member fixed inside the container, a driving section for switching ON and OFF between movable and stationary contacts of the movable and stationary contacting members is engaged to the projected end of the movable shaft for axial drive of the shaft.

Plural sealed contact units with common electromagnetic operating

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Itami, Japan

Kiyoshi Goto