Bbc Brown, Boveri & Company, Limited

Niyazi Ari

Diethard Hansen

Hans Schar

Hendrik Hoitink

Gerhard Linhofer

Zinc oxide surge arresters are used to replace capacitive elements for voltages below the pick-up voltage of the surge arrester. Advantageously, the surge arresters may be provided in an alternating current network to provide a high degree of protection against transient disturbances without increasing cost.

Zine oxide surge arresters

A gas-filled test cell is used which accommodates the object under test and to which a pulse generator is connected. The test cell is constructed over its entire length as a coaxial line having a ribbon-shaped inner conductor and a round outer conductor. A ribbon-shaped potential plate connected to the outer conductor is arranged plane-parallel to the inner conductor inside the outer conductor at a distance corresponding to at least twice the height of the object under test. The distance is also longer than the shortest distance between the inner conductor and the outer conductor. The ratio between the sum of the width of the inner conductor and its thickness and the diameter of the outer conductor has been selected in such a manner that is between 0.4 and 0.9.

Device for testing electrical or electronic systems with electromagnetic

The present invention relates to a protective device for a load connected to a power supply line of an electric power system, comprising an LC network having low-pass characteristics, connected into the power supply line on the system side preceding the load. So that disturbances with frequencies below the cut-off frequency of the LC network can also be kept away from the load, a switching element controlled by a monitoring device is arranged according to the invention in series with the LC network in the power supply line. The monitoring device is connected to the power supply line on the system side at a junction preceding the switching element and keeps the switching element closed only for as long as the instantaneous value of the time derivation of the voltage on the power supply line deviates from the instantaneous value of a nominal value which is predeterminable in its variation with time, by no more than an equally predeterminable amount.

Protective device for a load connected to a power supply line of an

Phase shifters are used in meshed, multi-phase power supply systems for improving their transmission stability and for load-flow regulating purposes. In order to be able to use a less costly exciter transformer of lower rating or the tertiary or compensation winding of a system coupling transformer for generating intermediate-circuit voltages as a function of system input voltages, a resonant circuit is provided between the exciter transformer and an auxiliary transformer. In this resonant circuit consisting of series-connected capacitors and inductive resistances which are connected to taps between these capacitors and can be switched in and out by means of alternating-current switches, tap voltages are generated which are supplied to the primary windings of the auxiliary transformer. At the secondary windings, connected in series with phase conductors of the auxiliary transformer, auxiliary voltages occur which are superimposed on the system input voltages and effect the desired phase shifts. Instead of air chokes which can be switched off, chokes with a ferromagnetic core or the impedance of a transformer, the secondary winding of which can be short-circuited by means of an alternating-current switch, can also be used as variable inductive resistances in the resonant circuit. The inductive resistances can also be star-connected instead of delta-connected.

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Nussbaumen, Switzerland

Niyazi Ari