SU828118A1 - Device for measuring dc electric network insulation resistance - Google Patents

Description

The invention relates to electrical measuring equipment and can be used in telemetry systems for measuring and monitoring the state of: dc network power supply with the power supply disconnected on power supplies for various purposes. A device is known for measuring the resistance of the insulation of a network of direct and alternating current, containing an ac alternator, connected to an “controlled network by means of a conductor. Through a capacitor (p and a controlled key, and a capacitor is connected in parallel to this loop). Adjustable capacitance, adder and block of measurement fl The device has the disadvantage of measuring accuracy due to a linear relationship between the measurement result and the insulation resistance and the effect of the network capacitance. measurement, as well as the apparatus complexity of the implementation of a, automatic-tuning, adjustable-capacitor in process-e (Intention. The most closely related to the invention to the invention is a bridge detector for isolating the insulating network of a steady-state current, rectangular shape, connected to a controlled network through a balanced resistor and in series with N. And: M - through a coupling capacitor with an input of an amplitude detector, and a DC amplifier 2 connected to it. stroystva relates izmeren1n low accuracy caused .nelineynoy za.visnmostyu melchdu result imereni and sol.rotivleniem insulation effect and N; iem e.mkosti network rezzltat measured | FL. The device also possesses a low fast action due to the need to use a test infrared frequency generator, the operating period of which is longer than the time required to establish the transition process in the network and the maximum values of the constant time network of the controlled network; There is no B03MOMvHOCTb automatic tuning of the frequency of the generator in the contact environment due to changes in the network parameters in the device circuit; in addition, there is a galvanic connection in the device. between the co-insulated network and a measuring circuit, as a result of which the measuring circuit shunts the insulation resistance by a constant current, reducing it, and the working voltage of the network is affected by this on the measuring circuit, which reduces the reliability of the device, especially the ave. and high network voltages.

The purpose of the invention is to increase the measurement accuracy in a wide range of network capacities and device performance.

This goal is achieved in that the device for measuring the insulation resistance of the DC network, containing the generator of rectangular impulses, the first coupling capacitor, the first terminal of which is connected to the input terminal of the device, and the DC amplifier connected to the output terminal of the device, are inserted second coupling capacitor, high-resistance repeater, integrator, analog differential memory unit, first, second and third keys, power supply unit, the first output of the second separating The capacitor is connected to the input terminal of the device, the second output is connected to the output of the square pulse generator and to the first input of the averaging unit, the first output of which is connected to the input terminal of the direct pulse generator and to the control input of the first key included in the integrator feedback, the input of which is connected to the second input of the control unit and to the output of the high-resistance repeater, whose input is connected to the second output of the first coupling capacitor, the integrator output through parallel The included second and third keys are connected to two inputs of an analog differential memory unit, the output of which is connected to the input of a DC amplifier, the second and third outputs of the control unit are connected respectively to the driving inputs of the second and third keys, and that the control unit contains the inverter, the first i the second elements And, are connected in series to the full-wave rectifier, comparator, the first and second one-shot, and the input of the inverter is connected to the nerve input of the etching unit and the first the first element and the output, with the first input of the second element, the second input of which is connected to the second input of the first element I and the output of the nerve one-vibrator, the input of the full-wave rectifier is connected to the second input of the control unit, the first output of which is connected to the output of the second single-pulse The second and third outputs, respectively, with the outputs of the first and second elements, And, the second - the input of the com parator is connected to the output of the voltage source.

FIG. 1 shows a block diagram of the device; in fig. 2 - time diagram of the device.

 The device contains a generator / rectangular impulses (Fig. 1) connected via a second coupling capacitor 2 to a controlled network 5, which is connected to an integrator 6 through a first coupling capacitor 4 and a high-impedance analog amplifier. the key 7, and the output of the integrator 6 through the controlled keys 8 iH 9 are connected to the input of the analog differential memory unit 10, which is connected to the output terminal of the device through a DC / DC amplifier

12, the control unit J3, containing a series-connected rectifier 14, a comparator 15, to the whose input input is fed a reference voltage Uo, and the first and; the second one are vibrators 1-6 and 17, and

 connected to the output of the generator / inverter 18, and two elements And 19 and 20, one outputs of which are connected to each other and to the output of the one-shot 16, and the voltage from the output of the generator / and the second input of the second element And - from the output of the inverter -M. The control input of the key 7 is connected to the output of the one-shot // and the synchronizing input of the generator /, and

the control inputs of the keys S and 5 are with the output of the And 19 and 20 elements, respectively. The inputs of the control unit 13-21 and 22, the outputs -; 23, -24 11.25.

The device works as follows.

The test voltage of a rectangular shape with an amilithic EQ (Fig. 2 a) from the generator / and fed through the second separator capacitor 2 to a controlled

network. 5.. On the insulation resistance K., the grounding of the earth to the capacitance of the network C d., The pulse signal is released (Fig. 2 b), for example, which is underestimated in the following way:

R,

Woo) -2 .. +

IM-2.: f - - at 1

  , + рС, 2 o7 4VЦ, (1)

 Sz be with

one

3 7G x

P +

. (c; tau

network impedance; resistance of the second coupling capacitor.

The transition from writing to temporary form, on the basis of (1) we obtain the expression dl. Lix (t):

, ....- .. /

.Cj -. (Q-gC,)

U (t) 2E,

, ()

Claims (2)

Оо Г t 1 where R (C, + С,) t. constant time of the monitoring network. The pulse signal lJ (t) selected by the network 3 is fed through the first coupling capacitor 4 and the high-resistance repeater 5 to the integrator 6. The voltage (ODS at its output (Fig. 2 g) is determined from the expression i /, b, x 4- ( (df 2E ,,, (C, t.) g (- 1 + CJ (1) - 4-2π, C, / ,, (-1), (3) where r is the integrator time constant. If the integration time is equal to Tint (4-5) t, then with a sufficient degree of accuracy to convert the expression (3) into the following: o - Eo - CzR From the expression (4) it can be seen that the output voltage of the integrator 6 t / o is proportional to the insulation resistance R and It does not depend on the capacitance network C .... At the end of each iolupe period, iroisholit is outputting the output voltage (/ o of the integrator 6 through the control keys 8 and 9 into the analog differential storage unit 10, and in even and odd semi-periods of the circuit and non-inverting inputs of the analog differential storage unit 10, respectively, which doubles at its output the amplitude value of the voltage i / gyx from the output of integrator 6, proportional to the volt-second area of the dedicated signal Ux (t). The same-field drift voltage of zero and integrator 6 is compensated for during one cycle. In feedback of the integrator 6, turn on the controllable key 7, which carries out the following operation in the memory of the iodact of the coagulator feedback circuit in the feedback of the integrator 5 to zero, than the integrator 6 prepares for the next half-period through the amplifier // and the current from the output of the analog differential storage unit 10 is fed to the output terminal 12 (fig. 2 d). The use of a memory unit 10 assembled according to a differential circuit in the device is due to the fact that the duration of the measurement cycle with a large constant network time reaches several minutes. The voltage of the zero drift of the integrator is 6 and this will be significant and may introduce significant instrumental error in the measurement result. However, this accuracy will be combined at the differential input of the memory unit 10, thereby contributing to an increase in the accuracy of measurement of the proposed device as a whole. The control unit 13 operates as follows. The input 22 is fed from a high-resistance repeater 3 a sparse signal extracted from the network / .- The voltage at the output of the rectifier 14 (Fig. 2 c) is fed to each comparator 15, where a comparison of the rectified signal with time occurs. Direction Uo. The voltage Ug is chosen in such a way that the moment of equality of these occurrences occurs after a time equal to 7 (4-5) /. I (Ca 4+ € 2) in the whole measurement range. At this moment, clock pulses begin to form, permitting recording from the output of the integrator 6 to the input of the memory block 10 via the second or third keys L and 9, respectively (Fig. 2 e and 2 g), which is provided by the inverter 18 and the And 19 and 20 elements, controlled by the generator 1, and the single-oscillator 16. Then, at the output of the one-oscillator 17, a reset pulse of the integrator 6 is generated to zero, which controls the opening of the key 7 (Fig. 2 h). The trailing edge of this pulse is the generator / switches to the fcd-rotted state. Thus, the control unit 13 performs an adaptive adjustment of the measurement cycle duration depending on the current isolation isolation values and network capacity throughout the entire range of variation of these parameters, thereby increasing the overall performance of the circuit and generates the information transfer sequence in the measuring cycle of the device. Claim 1. A device for measuring the co-current isolation of a DC network, comprising a square pulse generator, a first separator condenser, the first terminal of which is connected to the input terminal of the device, a DC amplifier and connected to the output terminal of the device, characterized in that In order to improve the measurement accuracy in a wide range of network capacity and device speed, a second coupling capacitor, high impedance repeater, integrator, analog differential are introduced The potential memory block, the first, second and third keys, the control unit, the first terminal of the second separator7 The capacitor is connected to the device's electrical terminal, the second output is connected to the output of a generator of mono-pulses and to the first input of the control unit, the first output of which is connected to the input of a synchro- nisal of the generator of rectangular impulses 11 with a handwheel and its nerve key input connected integrator, the output of which is connected to the second input of the control unit and to the output of the High-impedance Novortel, whose input is connected to the second output of the nerve of the separator condenser, the output of the integrator through parallel included the second and third switches connected to the two inputs of the analog differential block memory whose output to an input of soedinep ueplitel DC, and the second control unit tretny outputs respectively connected with the control inputs BTODoro and third keys. 2. Device for and. 1, it is possible that the control unit contains an inverter, the first and second elements AND, connected in series by two i-links 8 one driver, comnator, first and second one oscillators, and the input of the inverter is connected to the first input of the control unit and to the first input of the second element And, the second input of which is connected to the second input of the first element And, and the output of the nerve one-vibrator, the input of the full-wave rectifier connected to the second input of the control unit, the first output of which is connected with the output of the second sampler, the second and third outputs are respectively with the outputs of the nerve and the second element And, the second input of the comiaarator is connected to the output of the source nick support voltage. Information sources, taken into consideration 1.Aorekoy testimony of the USSR. 0 419808, cl. G 01 R 27/18, 1972. 2. Mokhovikov A. S. Measuring transducer for isolating a constant current network. Lime universities, Pribor .Stroii, t. X, N ° 5, 1967 (irotott). H