Toshimasa Jinzenji

Development of Zinc Oxide Ceramic Energy Absorbers for DC Thyristor Circuit Breakers

The performance and the overall bulk of low-voltage DC thyristor power circuit breakers explained in this article tend to be determined by the media in which circuit interruption is performed. The zinc oxide ceramic energy absorber is an extinguishing medium with capabilities beyond the counterparts used in the conventional high-speed circuit breakers. The withstand-voltage, the interrupting time and the surge energy to be extinguished during interrupting are considered, together with parameter values specified in JEC Standard. Each energy absorber for the prototype DC 1500V-3000A thyristor circuit breaker consists of twenty four 115 mmo 15 mm thick zinc oxide ceramic elements and is capable of absorbing 400 kJ. The performance of these assembled devices in an energy absorber and incorporated with a thyristor circuit breaker as well as in the discrete form have been verified.

Three-Phase Static Power Supplies for Air-Conditioned Electric Coaches using High Power GTO

The electrical design, characteristics, construction, and test results of a 170-kVA static power supply using 2500-V 600-A gate turn-off (GTO) thyristors developed for a wide range of electric railway applications are discussed. This power supply is principally composed of a thyristor chopper at an elementary frequency of 360 Hz and three-phase gate turn-off thyristor inverters in the form of a twelve-phase bridge configuration. It is capable of stabilizing a 60-Hz ac voltage and twelve-phase waveform. The bulk and weight of this power supply are ascribed to the avoidance of an inverter commutating circuit, which contains parasitic thyristors, capacitors, and inductances. The applied strategy is derived from the trend of the state of the art regarding switching cells and commuter trains.

GTO DC Circuit Breaker Based on a Single-Chip Microcomputer

A single-chip microcomputer is used to obtain a versatile GTO circuit breaker for electric railway substations. The microcomputer provides firing control, excellent dc short-circuit fault interrupting performance, precise overload protection of circuit breakers by themselves, as well as high reliability with minimum components. Emphasis is on the GTO junction temperature observation.

A GTO DC Circuit Breaker Controlled by a Single-Chip Microcomputer

Power semiconductor circuit-breaker application suggests the need for microcomputers that provide firing control, excellent dc short-circuit fault interrupting performance, precise overload protection of themselves, as well as high reliability with minimum components. This paper deals with the prototype dc 1500 V GTO (gate turnoff thyristor) circuit breaker controlled by a single-chip microcomputer. Emphasis is on the GTO junction temperature observation.

Characteristics of a Two-Phase Double-Superimposed Auxiliary Impulse Commutated Chopper

Circuit configurations, operations, characteristics, and evaluations of a two-phase auxiliary impulse commutated chopper are dealt with. The auxiliary impulse commutated chopper is composed of at least two main thyristors which alternately repeat turn on and turn off during each cycle operation. A commutating capacitor is commonly combined with the main thyristors to supply a commutating current for them in a reverse direction. A plurality of auxiliary thyristors is set for charging the capacitor in alternative polarities and selectively discharging through the main conducting thyristors. Since the first trial operation in 1968 of dc electric trains using the auxiliary impulse commutated chopper, this type of chopper cannot be disregarded for chopper electric trains.