RU2260190C1 - Relaxation measuring device for parameters of cg-dipole - Google Patents

Abstract

FIELD: measuring equipment.

SUBSTANCE: device has first and second standard voltage sources, comparator, analysis block, measured CG-dipole, commutating key. For measuring parameters of CG-dipoles also used are modulating capacitor, commutating key, block for controlling charge-discharge, electronic commutator, frequency divider, buffer.

EFFECT: broader functional capabilities.

2 dwg

Description

The invention relates to measuring technique and can be used to measure the components of the complex conductivity and relaxation time of CG two-terminal networks in a wide range of frequencies and measured values.

A device for measuring the capacitance of electric capacitors [1], containing a DC source, a power switch, a current meter, a field effect transistor, a set of model capacitors, a measured capacitor, a switch of measurement limits, a switch "measurement", a resistor in the source circuit and a resistor in the drain circuit field effect transistor. Due to the limitation of the frequency and dynamic characteristics by the field effect transistor, the measurement ranges of such a converter are narrowed.

The best characteristics are possessed by a capacitance meter [2], which contains the first and second sources of reference voltage, the first and second comparators, the analysis unit, the measured capacitor, in parallel with which a DC source and a switching key are connected, the control input of which is connected to the control output of the analysis unit, the interval meter time, and the outputs of the reference voltage sources are connected to the first inputs of the comparators, the outputs of which are connected to the inputs of the device measuring the time interval, the second input The comparator odes are connected to the capacitor being measured, the input of the analysis unit is connected to the output of the instrument measuring the time interval. However, this technical device does not provide measurements of conductivity and relaxation time.

The purpose of the invention is the expansion of the functionality of the capacitance meter.

This goal is achieved by the fact that in the capacitance meter containing the first and second sources of reference voltage, a comparator, an analysis unit, a measured CG two-terminal device connected to the first input of the comparator, a switching key, the control input of which is connected to the control output of the analysis unit, a modulating capacitor is introduced connecting the measured CG two-terminal network and a switching key, a charge-discharge control unit, an electronic switch, to the inputs of which the outputs of the first and second sources of exemplary voltage, and the output is connected to the second input of the comparator, the frequency divider, the output of which is connected to the second input of the analysis unit, the output of the comparator is connected directly to the control input of the electronic switch, to the measured CG two-terminal via the charge-discharge control unit, and to the input of the divider frequency and the first input of the analysis unit through the buffer.

Figure 1 shows the structural diagram of the device, figure 2 is a timing diagram explaining its principle of operation.

The device contains sources of exemplary voltage 1 and 2, an electronic switch 3, a measured CG two-terminal 4, consisting of conductivity 5 and capacitance 6, a comparator 7, a charge-discharge control unit 8, a modulating capacitor 9, a switching key 10, a buffer 11, a frequency divider 12, analysis unit 13.

The device operates as follows.

The voltage of the source 1 is the upper threshold for switching the comparator and is selected in the range of 70-80% of the voltage level at the output of the comparator 7, taken as a unit. The voltage of source 2 is the lower threshold for switching the comparator and is selected in the range of 20-30% of the voltage level at the output of the comparator, taken as zero.

At zero voltage, the unit voltage is set to the inverse input of the comparator, and the electronic switch 3 turns on the source 1, and the charge-discharge control unit 8 charges the measured two-terminal device in a time several orders of magnitude less than the discharge time. When the voltage at the inverse input of the upper threshold is reached, the voltage of the comparator is set to zero, while the electronic switch includes source 2, and the charge-discharge control unit goes into a state with high output resistance and the measured two-terminal is discharged to conductivity, i.e. relaxes until the voltage at the inverse input reaches the lower threshold.

The frequency divider 12 provides the connection / disconnection of the modulating capacitor and signaling the operating mode (with a modulating capacitor / without modulating capacitor) to the analysis unit 13. The modulating capacitor increases the relaxation time by increasing the capacitance without changing the conductivity. The pulse repetition period with disconnected and connected C _m , respectively, is determined by the expressions:

where A is the factor determined by the voltage values of sources 1 and 2, at the upper threshold, C ₀ is the initial value of the capacitance of the measuring circuit, C _x is the measured capacitance, G is the measured conductivity, C _m is the capacitance of the modulating capacitor.

The relaxation time is equal to the pulse repetition period with the modulating capacitor switched off:

τ = T.

The capacitance and conductivity of the measured two-terminal are determined by the formulas:

where G ₀ is the initial value of the conductivity of the measuring circuit.

Unlike existing devices, the device measures not only the capacitance, but also the conductivity and relaxation time, and tests have shown that the accuracy of measuring the capacitance of the proposed technical device is 10-15% higher than that of other capacitance meters.

Bibliography

1. A.S. No. 93047134, Russia, 1996.

2. Pat. NDP, Cl. G 01 R 27/26, No. 103289, declared. 04.10.75, No. 183765, publ. 09/29/79.

Claims (1)

Relaxation parameter meter of CG-two-pole, containing the first and second sources of reference voltage, a comparator, an analysis unit, a measured CG-two-pole, connected to the first input of the comparator, a switching key, the control input of which is connected to the control output of the analysis unit, characterized in that a modulating capacitor has been introduced, connecting the measured CG two-terminal device and a switching key, a charge-discharge control unit, an electronic switch, the inputs of which are connected to the outputs of the first and second sources of reference voltage, and the output is connected to the second input of the comparator, the frequency divider, the output of which is connected to the second input of the analysis unit, the output of the comparator is connected directly to the control input of the electronic switch, to the measured CG two-terminal network via the charge-discharge control unit, and to the input of the frequency divider and the first input of the analysis unit through the buffer.

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