SU798630A1 - Apparatus for measuring capacitor loss tangent - Google Patents

Description

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This invention relates to electrical measurements and may be used to measure the characteristics of high-capacity capacitors.

An automatic semi-balanced bridge for measuring capacitance to the loss tangent of capacitors is known, which includes a dead generator, a bridge measuring circuit with inductively connected arms, an exemplary variable capacitor, a modulator, an automatic balancing unit, and a recording unit i.

A disadvantage of the known device is the low measurement accuracy, since the measurement result is strongly influenced by the active resistance value of the inductor.

The closest to the proposed technical entity is a Q-factor meter, which contains a master oscillator, a power amplifier, and a supply measuring circuit with series-connected inductors and a reference capacitor G2.

A disadvantage of the known device is that when measuring

Q Q of the capacitor (loss angle tgdc.) of a large capacitance at low frequencies; the Q of the measuring circuit is mainly determined by the active resistance of the inductance, which exceeds the active resistance of the capacitor under investigation.

The purpose of the invention is to improve the measurement accuracy.

This goal is achieved by the fact that the device containing the master oscillator to which is connected

measuring circuit formed by reference and test capacitors connected in series with the inductor through a switch, a recording unit connected in parallel with the measuring circuit, a compensation inductor introduced inductively connected to the measuring loop and connected to the master oscillator through an amplifier with adjustable gain and phase shifter.

The drawing shows the principle scheme of the device for measuring

loss tangent capacitor.

The device contains a master oscillator 1 supplying voltage to amplifier 2 and phase shifter 3. Amplifier 2 supplies measuring circuit 4 with inductance coil 5 connected in series, a reference capacitor 6 and a capacitor under test 7. From phase shifter 3, the voltage is applied to an amplifier 8 with an adjustable gain factor , which feeds the compensation circuit 9 with the series-connected capacitor 10 and the inductor 11, inductively connected to the inductor 5. The registration unit 12 is graduated in elichinah tg (f (and connected to the circuit 4, switch 13 serves to turn on the measuring circuit 4, the exemplary capacitor 6 and capacitor 7, the test, as well as connecting the compensation circuit 9 to enhance Yeh-lii 8.

A device for measuring the loss tangent of capacitors operates as follows.

Switch 13 includes a capacitor 7 under investigation into measuring circuit 4. At a given frequency, installed on a backward generator 1, and a predetermined operating voltage set by amplifier 2, measuring circuit 4 is set to resonance by adjusting the value of inductance 5 of the coil. Switch 13 disconnect the research capacitor 7 and include an exemplary capacitor b. Selecting the value of the reference capacitor 6, adjust the measuring circuit 4 to resonance. Switch 13 disconnects the reference capacitor b and connects the compensation circuit 9 to the amplifier 8. Adjust the circuit 9 to resonance by changing the capacitance capacitance 10. The switch and turn on the measuring

circuit 4 is an exemplary capacitor 6. By adjusting phase 3 with the phase shifter, and by amplifier 8, the amplitude of the signal from generator 1, the voltage on the measuring circuit 4 is fully compensated, which is registered by means of the registration unit 12. Switch 13 disconnects the reference capacitor b and connects the capacitor 7 under investigation. By means of the registration unit 12, the value of the loss tangent of the condensate under study is measured at 7,

The proposed device allows measurements to be made at operating voltages up to 300 V at low frequencies for tg with high accuracy.

Claims (2)

1. The author's certificate of the USSR 199990, cl. G 01 R 27/26, 1966. 2. Instruments for measuring parameters of chains with lumped parameters, R4-4. Catalog of products of the radio industry. t.Z., M., 1973.