Development of 24-kV Switchgear with Multi-functional Vacuum Interrupters for Distribution

• Volume 49 Number 2 August 2000

• Power Systems

AUTHORS

OVERVIEW

Increasing demand for electric power in recent years as well as the difficulty of constructing new substations due to rising land prices have generated a need for boosting conventional 6-kV distribution. The relatively large size and high cost of 22-kV distributors compared to 6-kV ones, however, have provided an obstacle to their introduction. Against this background, Tokyo Electric Power Co., Inc. and Hitachi, Ltd. have jointly developed a switchgear with multi-functional vacuum interrupters enclosing a circuit breaker, a disconnecting switch, and an earthing switch. This switchgear is no larger than the 6-kV device and sufficiently satisfies initial objectives. Its reduced size has been achieved through a '4-position vacuum valve' that integrates a switching section consisting of a circuit breaker, a disconnecting switch, and an earthing switch. While the electrode inside the old vacuum valve could only move in a linear direction, the electrode in this new 4-position vacuum valve can move in an arc due to the development of barrel-shaped bellows. This arc movement provides a long stroke compared to that by linear movement, and has made it possible to establish four positions within the stroke and therefore achieve a significant reduction in equipment size. This switchgear with multi-functional vacuum interrupters has been delivered to 12 sites since December 1998 and its expansion to general private use and overseas markets is now being planned.

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RELEVANT SITES

	Power & Industrial Systems
	The Hitachi Hyoron (Japanese Only)

KEYWORDS

Switchgear, SF6 gas, Vacuum Interrupters, bellows

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