SU1314281A2 - Device for checking insulation resistance of d.c.line - Google Patents

Abstract

The invention relates to a technique of electrical measurements, namely, devices for monitoring the resistance of two-wire DC lines, and is an improvement of the invention by auth. No. 612186, The device contains an amplifier cascade made on two operational amplifiers 1.2, a divider 3 voltages, exemplary resistors 4-7, diodes 8.9, light elements 10.11 and sound 12 alarms, logic elements 13 , 14, counters 15, 16 pulses and timer 17, Introduction to the device of new electrical connections between functional elements increases the reliability of control by eliminating false alarms due to voltage surges during load switching, instability of the insulation resistance of each of the buses pi tany in a controlled network with respect to the case, caused by external conditions (temperature, humidity, pollution of the environment) and operation mode. 2 Il. (L with 14)

Description

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The invention relates to an electrical measurement technique, namely to devices for monitoring the insulation resistance of two-wire DC lines.

The purpose of the invention is to determine the reliability of control by eliminating false alarms caused by surge voltage during switching of the load, instability of the insulation resistance of each of the power lines in the controlled network relative to the housing, caused by external conditions (temperature fluctuations of humidity, pollution of the environment, etc. .) and mode of operation.

FIG. shows a block diagram of the proposed device; Fig.2strukturnaya scheme timer.

The device contains an amplifier stage made on two operational amplifiers 1 and 2, a voltage divider 3, four exemplary resistors 4-7, diodes 8 and 9, light elements 10 and 11, and sound alarm element 12, two AND 13 and 14 logic elements , two counters 15 and 16 pulses. And a timer 17, wherein the output of the first operational amplifier through the first logical element I 13 serially connected, the first counter 15 and the first diode 8 is connected to the first output of the sound alarm element 12, to which also in series nye second AND gate 14, a second counter 6 and A second diode 9 is connected the output of the second operational amplifier 2 to the inverting input of which is connected nap divider 3. and the non-inverting input of which is connected to the common bus through the second exemplary resistor 5, the inverting input of the first operational amplifier 1 is connected via the first exemplary resistor to the common bus, and its non-inverting input connected to the inverting input of the second differential amplifier 2. Elements 10 and 11 of the light indications are connected respectively to the outputs of the first 15 and second 16 counters, the outputs of timer 17 are connected respectively to the second inputs of the elements And 13 and 14 and the installation inputs of the counters 15 and 16, the outputs of which x are connected to the inputs of the timer 17,

12

Timer I7 contains a timer element 17-1, the output of which is through a differentiating circuit consisting of a capacitor 17-11 and a resistor 17-III,

and the trigger 17-IV Schmidt is connected to the first input of the first element OR 17-V. The inputs of the second element OR 17-VI are the inputs of timer 17, and the output of the second element OR 17-VI

connected to the control (CE) input of the counter 17-VII, the output of which is connected to the second input of the first FDI element, 17-U, the output of which is connected to the inputs of the installation (R) of the timer 17, as well as the counters 15 and 16.

The device works as follows.

Divider 3 voltage selected by

dir1-1mu input current operating

the amplifier 1 (2) and the controlled value of the insulation resistance R, to which the measuring bridge circuits made up of exemplary resistors 4-7, the voltage divider 3 and the resistances R from the tin - and + monitored network are tuned. The elements of the bridge circuit (3 and 4-7) are standard requirements for stability and accuracy.

When the insulation resistance of one of the busbars (+ or -) of the controlled DC line drops below the threshold to which the measuring bridge circuits are tuned by the divider 3, then the output of the operational amplifier 1 (2)

a positive voltage arises, which is fed to the input of the AND 13 (14) logic element, to the other input of this element are supplied the clock pulses from timer 17. At the same time, the clock pulses are passed to the input of the counter 15 (16) and summed over the time determined by the capacity of the counter 15 (16) pulses. If, during the measurement cycle, all expected pulses from an AND 13 (14) 5 element arrived at the input of the counter 15 (16), then the output N of the counter 15 (16) of the pulses is the activation signal of the display element 10 (11) and the alarm element 12,

which registers a decrease in the insulation resistance of one of the tires (or on both) below the set threshold .. This signal, due to feedback, stops the counting

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pulses in counters 15 (16) and 17-VII (CE inputs). It is possible to restore the operation of the control device when the power supply to the digital part of the circuit is removed and switched on (elements I 13 and 14, counters 15 and 16 and 17) Schmitt's IV generates a reset pulse for counterbatches 15 and 16 and 17-7 (for inputs R). In the event that during a measurement cycle the value of resistance R, the insulation is unstable in such a way that it takes values both above the threshold of the measuring bridge circuit and below, then to the input of the counter 15 (16) pulses, as a result, pulses; . will be received; only at those times when Cc will be below the threshold of adjustment. At other points in time, the pulses to the input of the counter 15 (16) will not be received, since the logic element AND 13 (14) will be closed by a low level of the output voltage of the operational amplifier 1 (2). Thus, for the measurement cycle of the account; The pulse 15 (16) of the pulses will be incompletely filled and the output of the counter does not generate a turn-on signal for the display element 10 (11) and the alarm element 12. However, the counter is 17-VII tay14

the measure is filled up to the appearance of a signal at the output of N equal to +1. This signal through the OR element 17-V goes to reset the counters 15 and 16 AND 17-VII. The formation of a reset signal is characteristic of those measurement cycles when there is no steady decrease in the insulation resistance below the set threshold. On this cycle

measurement is completed and digital

a part of the control device is reset to its original state; Starting operation in the new measurement cycle i

Claims (1)

Claims of Invention A device for monitoring the insulation resistance of a DC line according to the author No. 612186, characterized in that, in order to increase reliability, the output of each operational amplifier is connected to the first terminals of the light signaling elements and the diodes through the series-connected element And and counter, while the second inputs of the And elements are connected to the output of the timer clock signals, the reset bus of which is connected to the second inputs of the counter, the output of which is connected to the third inputs of the counters and the input of the timer. ..0 f7 - / - 2 1 iUYP Hff l t llfPtOOSBHI TT-Shch / 7 - / - J Compiled by H. Mikhailov Editor A. Revin Tehred L. Oliynyk. H.-- -----Order 2209/46 Circulation 731 Subscription VNIIPI USSR State Committee for inventions and discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production printing enterprise, Uzhgorod, st. Project, 4 iUYP t / 7-M / 7-f 17-3    t-l- f / c / 7- /