Kabushiki Kaisha Toshiba

Masahiro Kan

Hironori Suzuki

Yoshiyasu Itoh

Masahiro Hanai

Yoshihiko Hirano

Nobuyuki Shimizu

Takahiko Shindo

Hideyasu Andoh

Hiroyoshi Narita

Takeshi Udagawa

Katsuaki Komatsu

Yasuhiko Taniguchi

Yoshihiro Ishizaki

Masahiko Ebina

Keisuke Shimagami

Yoshihide Kayano

A voltage non-linear resistor unit is composed of at least one of voltage non-linear resistors which is composed of a columnar sintered body formed by molding and sintering a raw material, the sintered body having both end surfaces having a surface roughness in term of arithmetic average surface roughness Ra of 1 to 2 &mgr;m and being formed with an electrode film layer, a terminal metal fitting formed in a predetermined shape and attached to the voltage non-linear resistor, and a soldering material arranged between the voltage non-linear resistors and between joint surfaces of the voltage non-linear resistor and the terminal metal fitting, the joint surfaces being joined by heating the soldering material and applying a load vertically to the joint surfaces while giving a rotation motion thereto. Such voltage non-linear resistor is effectively assembled into an arrester.

Voltage non-linear resistor unit and arrester unit

An arrester in the shape of a tank has a cylindrical grounding tank as an outer casing to be arranged vertically in which an insulating medium is enclosed. In the grounding tank, a non-linear element group is disposed, the non-linear element group is formed by vertically stacking a plurality of non-linear resisting elements in series at a substantially axially central portion of the grounding tank. A shield having an umbrella-like shape is disposed on a high potential side of the non-linear element group. A shielding unit is operatively connected to a low potential side of the umbrella-shaped shield through a support member. The shielding unit comprises at least one shielding member having a spherical shape provided with a spherical surface portion facing an inner side wall of the grounding tank. When two shielding members are disposed, they are positioned axially symmetrically with respect to the non-linear element group, which comprises a single column or a plurality of symmetrically arranged columns of non-linear resisting element stacks standing upwards along the central axis of the grounding tank.

Tank-shape arrester

An apparatus for detecting degradation of a grounded arrester, including a wave conversion circuit for producing an output signal corresponding to the total leakage current flowing through the arrester, and a phase shifter circuit coupled to the output signal for providing a capacitive-component leakage current signal, which is cancelled from the total leakage current signal by means of a differential amplifier to produce a resistive-component leakage current signal. According to one embodiment, this latter signal is applied to a synchronous rectifier circuit for synchronous rectification of the output signal from the differential amplifier circuit. A real resistive-component leakage current signal is then detected by adjusting the phase shift amount in the phase shifter circuit so that the output signal from the synchronous rectifier circuit may become zero, thereby bringing the phase of the cancelling wave signal in agreement with the phase of the capacitive-component leakage current signal. In another embodiment, the resistive-component current leakage signal is applied to a multiplier and a time averaging circuit, the output of which is likewise nulled by means of the adjustable phase shifter.

Apparatus for detecting degradation of an arrester

Growing community of inventors

Yokohama, Japan

Masahiro Kan