SU117573A1 - A method for measuring impulse voltages and a device for implementing this method - Google Patents

Description

For measuring the amplitude values of the pulse voltages, methods are used based on full compensation of the measured pulses by a DC voltage, the value of which, after reaching compensation, is measured by an accurate magnetoelectric voltmeter.

The disadvantage of all these methods is the difficulty of setting the moment of full compensation with a high duty cycle of the measured pulses, since the current indicator in these cases is a magnetoelectric galvanometer, measuring the average value of the pulse.

The proposed method makes it possible to eliminate this drawback and to ensure a significant increase in the measurement accuracy of pulsed voltages. For this purpose, it is proposed to measure most of the pulse voltage by the compensation method, and to measure its uncompensated value with a conventional amplitude voltmeter or to measure it on the screen of a cathode oscilloscope.

FIG. 1 is a schematic diagram for measuring the pulse voltage of the proposed method; in fig. 2 and 3 are diagrams of a device for measuring an uncompensated portion of a pulse with positive and negative pulses.

The measured impulse voltage and „, obtained from diode L is partially compensated by a constant voltage Uo and measured by a magnetoelectric voltmeter 2. The uncompensated part of the measured voltage AU is measured by a pulsed voltmeter 3 or determined on an oscilloscope screen.

The load resistance 4 is many times greater than the internal resistances of the diode and source {/ „Uo-De-f D (7,

where: Ae - voltage lock up the diode.

The constant voltages t / o and Le can be measured with great accuracy (when measuring Ae, the voltage U must be turned off, and the indicator of the threshold can be, for example, micro-number. 117573

DC ammeter connected to the diode circuit). The voltage Af7 is measured with the usual accuracy for a given pulsed voltmeter, but since Af / and "to measure accuracy 7" is much higher than the accuracy of measurement Lb.

When measuring negative pulsed voltage, it is necessary to change the polarity of the diode and the constant voltage.

To measure the uncompensated part of the pulse, a device can be applied containing a pentode 5 electron tube (Fig. 2) or a triode 6 (Fig. 3), a calibrated pulse generator 7. a broadband amplifier 8, and an oscilloscope 9.

When measuring positive pulses, the switch 10 is first set to the upper position, as a result of which a measured pulse and the pulse are applied to the grid of the lamp 5, simultaneously with a constant negative bias Eg.

The uncompensated part of the pulse opens the lamp 5 and is amplified by the amplifier 8. At the same time, the amplitude of the amplified part of the pulse is recorded on the screen of the oscilloscope 9.

Then, the switch 10 is set to the lower position and the calibrated pulses of a low voltage U from the generator 7 are applied to the lamp 5. The bias voltage decreases to a value „at which the borders of the image on the screen coincide with the marks in the first measurement.

. The magnitude of the pulse can be calculated by the formula:

and „() + and,

When measuring negative pulses, the cut-off of the pulse is produced by the triode 6. In the upper position of the switch 10, the offset E g is chosen small, so. so that lamp 6 is securely locked by a voltage drop across its cathode resistance. For the rest, the measurement is performed in the same way as with a positive impulse.

The accuracy of measuring the pulse voltage is much higher than the accuracy of calibrated pulses, since U and the accuracy of determining Eg can be very high.

The advantage of this circuit is a large input impedance, low pass capacitance and a large transfer coefficient of the restrictive element.

Subject invention

Claims (2)

1. A method of measuring pulsed voltages based on the compensation of a measured pulse by a DC voltage, characterized in that, in order to increase the measurement accuracy, by the compensation method, the most part of the pulse voltage is measured and the uncompensated value of it is measured by an amplitude voltmeter , or counted on the screen of the cathode oscilloscope. 2. A device for carrying out the method according to claim 1, comprising a triode or pentode type electron tube, onto the grid of which a measured pulse is applied simultaneously with a constant offset, compensating the most part of the pulse amplitude, characterized by comparing the uncompensated part of the pulse by comparing its calibrated pulses on the oscilloscope screen applied a source of calibrated pulses connected via a switch to the grid of the same lamp.