SU1226346A1 - Method of determining capacitance and dielectric loss tangent of capacitors - Google Patents

Abstract

The invention relates to electrical measurements and is used to measure parameters of complex electrical resistances. The purpose of the invention is to reduce the measurement time, especially when measuring at infrared frequencies. The device, implemented in the following way, contains a generator 1, an active load 2, a capacitor 3, a block 4 and 5 of sampling and a fault of an analog signal, an electronic switch 6, a voltmeter 7, a computer 8, countdown. unit 9, one-shot 10, timer 11, and element 12 OR, the measurement of instantaneous voltage values on the generator and capacitor is carried out simultaneously two times with a shaft interval of time that does not exceed a quarter of the generator frequency period. The description presents the formula for calculating the capacitance value and the dielectric loss tangent of a capacitor. 1. il. i (Л с: ю to О5 со 4: о:

Description

ten

15

The invention relates to a measuring technique for measuring parameters of complex electrical resistances and can be used in instruments for measuring capacitance and the tangent of the angle of electrical losses at infrared frequencies.

The purpose of the invention is to reduce the measurement time of capacitance and the dielectric loss tangent of a capacitor, which is especially necessary when measuring at infrared frequencies (below 1 Hz).

The drawing shows a block diagram of an apparatus for implementing a method for determining the capacitance and 8 capacitors.

The output of generator 1 in series with active load 2 (a resistor whose resistance is known) is connected to a controlled capacitor 3. The output of generator 1 is connected to the first block 4 of sampling and storing an analog signal, and to the output terminal 20 of active load 2 n 3 - in the head unit 5 of sampling and memorization. The outputs of both blocks 4 and 5 are connected via an electronic switch-6 to an external voltmeter to a digital voltmeter 7, the information outputs 25 of which are connected to a computer 8, the output of which is connected to a reading unit 9. The output of a single vibrator 10 is connected to the input of a timer 11 and to one of the inputs logical element OR 12, to the second input of which is connected to the output of the timer 11.

When the measurement process starts at some time, the one-shot 10 produces a pulse and, through the logic element OR 12, gates memorizing the instantaneous voltages on the generator 1 and the capacitor 3 in blocks 4 and 5, selecting the Esy and storing the analog gagnal, respectively. The same pulse pulses the AND key, and the computer 8 is informed of the end of the first sample of instantaneous voltages.

After that, before the expiration of the time interval it, measured by timer II, the stored instantaneous voltages are sequentially switched by computer commands 8 by an electronic switch 6 to the input of a digital voltmeter 7 measuring their values. The results are entered into the computer 8. According to the time t from the moment of starting the Measurement Process, timer 11 generates a pulse that, through a logical element OR 12, gates the repeated simultaneous memorization of voltages on the generator

12263462

and the capacitor 3 by the blocks 4 and 5 with the subsequent measurement of their values and the input of the results into the computer 8, as described. The computer 8. Calculates the capacitance and tangent values of the dielectric loss angle of the capacitor 3 according to the above formulas and indicates their values on the reading unit 9. The measurement process is completed.

thirty

35

40

45

Claims (1)

Invention Formula The method for determining the capacitance and tangent of dielectric loss of capacitors by supplying a capacitor from an alternating voltage generator through a resistive load, measuring voltage values on a generator and a capacitor, and mathematical processing of measurement results, characterized in that, with an increase in speed, the measurement the instantaneous values of the voltages on the generator and the capacitor are simultaneously, and after a time interval not exceeding a quarter of the generator frequency period, one more time is repeated time measurement Instantaneous: 1s voltage on the generator and capacitor, then 1easschitsya capacitance and tangent of dielectric loss angle of the capacitor according to the formulas s-iT ut Tl) n-Uc2-Ur2-iJcA SO gin; g y ,, - 2Uc, -UcrCoe r..t 2. (Uca-Uc., - Uc, V (Uc ,,.) (A, -U, 5ln2 (u ,,. Uc, -Ur.-Uc,) where C is the capacitance of the measured capacitor parallel to the replacement circuit, μF; ut T the interval-time between the moments of the first and repeated voltage measurements, s; frequency period of alternating voltage generator, s; R is the resistance of the active load, l / Hume;   voltage on the generator at the first to repeated measurements, V; Up, ll (-2 is the voltage across the capacitor during the first and repeated measurements, B; iq, 8 is the tangent of the dielectric loss angle of the condenser. Invention Formula The method for determining the capacitance and tangent of dielectric loss of capacitors by supplying a capacitor from an alternating voltage generator through a resistive load, measuring voltage values on a generator and a capacitor, and mathematical processing of measurement results, characterized in that, with an increase in speed, the measurement the instantaneous values of the voltages on the generator and the capacitor are simultaneously, and after a time interval not exceeding a quarter of the generator frequency period, one more time is repeated time measurement Instantaneous: 1s voltage on the generator and capacitor, then 1easschitsya capacitance and tangent of dielectric loss angle of the capacitor according to the formulas s-iT ut Tl) n-Uc2-Ur2-iJcA gin; g y ,, - 2Uc, -UcrCoe r..t 2. (Uca-Uc., - Uc, V (Uc ,,.) (A, -U, 5ln2 (u ,,. Uc, -Ur.-Uc,) capacitance of the measured capacitor parallel circuit replacement, μF; the interval-time between the moments of the first and repeated voltage measurements, s; frequency period of alternating voltage generator, s; resistivity of active load, l / Hume; voltage on the generator at the first to repeated measurements, V; the voltage across the capacitor during the first and repeated measurements, V; the tangent of the dielectric loss angle of the condenser. Yo ™ 1C. i-L lBPi ii Produced polygraph, pr-tie, Uzhgorod, st. Design,