Capacitive voltage divider for measuring high voltage pulses with millisecond pulse duration

Abstract

In a capacitive voltage divider for measuring high voltage pulses with millisecond pulse duration comprising a high voltage divider including a first cascade of at least two serially arranged condensers of which one (C1) is disposed at the high potential end and another (C2) is disposed at the low potential end of the cascade, and a measuring voltage divider connected to the other condenser (C2) and including a second cascade of at least first and second serially arranged condensers (C3, C4) arranged, respectively, at the high and low potential ends of the second cascade with the second condenser being connected with its low voltage side to a signal supply line leading to a measuring device, and an ohmic resistor (R1) arranged in parallel with the first condenser and a resistance (R2) connected to the one and first condensers in parallel with the second condenser (C4), the ohmic resistor (R1) is so dimensioned that 1.1<C4*R2 / C3*R1<1.15.

Description

[0001] This is a continuation-in-part application of international application PCT / EP99 / 04772 filed Jul. 07, 1999 and claiming the priorities of German applications 198 33 179.7 filed Jul 23, 1998 and 199 23 211.3 filed May 02, 1999.BACKGROUND OF THE INVENTION[0002] The invention resides in a capacitive voltage divider for measuring high voltage pulses with millisecond impulse duration.[0003] For measuring high voltage pulses in the nano- and microsecond range, simple capacitive voltage dividers are used. The high voltage part of such a divider consists generally of at least one cylindrical condenser, which is disposed within a pressurized insulating gas or an insulating oil. Depending on the desired divider ratio K, the low voltage part of the high voltage divider may be disposed in the same space as the high voltage part (about K<100) or it may be arranged separately therefrom (about K>100). With commercially manufactured condensers, the voltage divider is generally designed...

AI Technical Summary

Benefits of technology

[0013] With this arrangement, the accuracy of the voltage measurement with a pulse duration in the millisecond range is improved from presently about .+-.7.5%--depending on the component dimensioning--to less than .+-.0.02%, while maintaining the temperature stability of the capacitive high voltage dividers built in accordance with today's state of the art.

[0015] Preferably, the high voltage cascade is disposed in a dielectric medium at least up to the condenser with the lowest potential. With an appropriate containment, the dielectric medium of the cascade of the high voltage divider may be pressurized particularly with a compact structure, which provides for high dielectric strength.

[0016] The advantage of such a voltage divider is that immediately after applying a rectangular high voltage pulse the voltage at the input of the measuring instrument or the measuring amplifier is determined by the ratio of the capacities in the high voltage divider. The accuracy of the voltage measurement at the end of the rectangular pulse with millisecond duration is improved by the dimensioning of the resistor above the upper condenser in the measuring voltage divider by orders of magnitude.

Problems solved by technology

The measuring error occurring with temperature changes may well be several percent.

However, it is not suitable for measuring pulses in the millisecond range since, at the end of a 1.5 msec pulse, the measuring error may reach 15% and even more.

The signal is therefore not useable for control and monitoring tasks.

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