SU868630A2 - Device for measuring capacitive and active conductivity - Google Patents

Description

one

The invention relates to a measurement technique and can be applied to measure the capacitive and active conductivity of a two-terminal network in a certain ratio at several frequencies simultaneously, with output in the form of normalized DC voltage pulses.

According to the main author. St. No. 514247, a device for measuring capacitive and active conductivity is known, comprising a generator, capacitors, filters, measuring and reference arms, diodes, a diode is connected parallel to each arm, and the terminals of the diodes of one polarity are connected to a common connection point between measuring and reference arms, the second end of the measuring arm is grounded, and the second end of each of the reference arms is connected to the filter and through a capacitor to the generator tl3.

The drawback of the device is the dependence of its readings on the amplitude of the voltage of the generators, which causes a lack of accuracy when operating for a long time (several months and years) without calibration and maintenance.

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

The goal is achieved by the fact that a device for measuring capacitive and active conductivity, containing an oscillator, capacitors, filters, measuring and reference shoulders, diodes, a diode is connected parallel to each arm, and the terminals of the diodes of one polarity are connected to a common

15 the junction of the measuring and reference arms, the second end of the measuring arms being grounded, and the other end of each of the reference arms being connected to. filter and through a capacitor with

Claims (1)

generator, a stable voltage source, chains of series-connected two-terminal and key connected in parallel to each reference arm, second keys, the inputs of which are combined and connected to the output of a stable voltage source, and outputs connected to the outputs of the device, filter outputs are connected with control inputs of keys. The drawing shows the block diagram of the device. The device consists of reference arms 1-3, connected at one end through capacitors 4-6 to generators 7-9, respectively, and to the measuring arm 10 and the measured two-terminal And, filters 12-14, chains not connected in series by the standard two-terminal 15- 17 and keys 18, 19, 20, 23, second keys 21 and 22, a stable voltage source 24, and device output terminals 25-27. The device works as follows. Generators 7-9 feed the voltage of certain frequencies through capacitors 4-6 to reference shoulders 1-3 and chains of reference two-terminal 15 17 and keys 18-20, through which the voltage goes to the measuring shoulder 10 and the measured two-terminal 11. Consider the process when the key is locked 18. In the positive half-period of the supply voltage, the diode of the reference arm 1 is locked, and the diode of the measuring arm 10 is open, the ard passing through the half-period through the capacitor 4 is proportional to the conductivity of the reference arm 1. In the negative half-period of the supply voltage The diode of the measuring arm 10 is locked, and the diode of the reference arm 1 is open, the charge passing through the half-period through the capacitor 4 is proportional to the total conductivity of the measuring arm 10 and the measured two-terminal circuit I1. If the conductivity of the reference arm I and the total conductivity of the measuring arm 10 and the measured dvuhpolannika 1 1 are equal, then the charges passing through the capacitor 4 and the constant voltage component, equal to zero. If the total conductivity of the measuring arm 10 and the measured two-terminal 11 exceeds the conductivity of the reference arm 1, an increasing constant voltage component appears on the capacitor 4, you are 04 using a filter 12. This constant component voltage opens keys 18 and 21 , the key 18 connects the reference two-pole 15 parallel to the reference arm I, and the key 21 supplies the voltage from a stable voltage source 24 to the input terminal 25. When the reference two-pole 15 is connected parallel to the reference shoulder I, their total the conductivity exceeds the total conductivity of the measuring arm 10 and the measured two-terminal 11, the constant component of the voltage on the capacitor 4 and, accordingly, on the filter 12 decreases. After some time, due to the constant filter time 12 and the ratio of the conductances of the arms 1 and 10, as well as the two-terminal networks 1 and 15, the value of the constant component voltage on the filter 12 decreases to the value at which the keys 18 and 21 close. reference two-pole 15 from reference arm 1, and the key 21 removes the voltage from the output terminal 25. The conductivity of the reference arm 1 again becomes less than the total conductivity of the measuring arm 10 and the measured two-pole 11, the component voltage capacitor 4 begins to increase, and the process is repeated. Since the rate of change of voltage on the capacitor 4 is proportional to the difference in the conductivities of the arms, the width of the stable voltage pulses at the output terminal 25 is proportional to this difference. Thus, the magnitude of the output signals at terminals 25-27 depends only on the magnitude of the stable voltage (amplitude of the pulses) and the difference between the shoulders with the reference two-terminal 15-17 and the measured two-terminal 1I (pulse width) and does not depend on the amplitude of the high-frequency voltage generators 7-9, which significantly improves the accuracy of the device, especially when it is used for long periods of time. The invention The device for measuring capacitive and active conductivity according to the authors. St. No. 514247, characterized in that, in order to increase the accuracy