Abb Research Ltd.

Bbc Brown, Boveri & Company, Limited

Ruzica Loitzl

Klaus Muller

Joachim Glatz Reichenbach

Ron Hutchings

Jo Slashedrgen Skindho Slashedj

Zdenek Pelanek

Jan Kuhlefelt

Edgar Dullni

Ralph Strumpler

A power switching apparatus is disclosed which has an electrical conductor to which high voltage can be applied. A series of circuits formed by a switching point and a current-limiting element which contains PTC thermistors and varistors is arranged in the cable run of the electrical conductor. An apparatus for operating the switching point interacts with the current-limiting element. The current-limiting element has n (where n is a natural number greater than 1) series-connected parallel circuits each having at least one PTC thermistor and at least one varistor connected in parallel with it. A current sensor arranged in the cable run of the electrical conductor or those connections of one of the PTC thermistors and of the varistor connected in parallel with it which are interconnected at two junction points in one of the parallel circuits are operatively connected to the input of the operating apparatus. Such a power switching apparatus is designed using economic components, such as PTC thermistors and varistors for low-voltage applications, and a switching device which is designed for switching only low currents and can effectively limit large and small short-circuit currents without the current-limiting element connected upstream of the switching device, and/or the switching device, being overloaded.

Power switching apparatus

A catalytic powder for coating an anode consisting essentially of 2-45 mol % of RuO.sub.2, 2-45 mol % of IrO.sub.2 and 10-96 mol % of SnO.sub.2. The powder has a rutile crystal type, at least partially as a mixed oxide and has uniform lattice parameters which lie between the values of RuO.sub.2 and IrO.sub.2 and the value of SnO.sub.2. This catalytic powder is prepared by treating H.sub.2 IrCl.sub.6.m H.sub.2 O, RuCl.sub.3.n H.sub.2 O and SnCl.sub.2, wherein m is between 4.1 and 5.5 and n is between 2.5 and 3.85, with an alcohol. The resulting solution is then evaporated. The powder obtained is dried and ignited for 1/2 to 6 hours between 400.degree.-500.degree. C. and then cooled.

Catalyst for coating anodes and a process for its preparation

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Kirchdorf, Switzerland

Ruzica Loitzl