SU737874A1 - Insulation resistance measuring device - Google Patents

Description

The invention relates to the field of electrical measurements, which can be used to measure insulation resistance in direct current networks. A device for controlling the insulation resistance is known, which has special differential transformers that are included in the break of the supply network. With a decrease in the network insulation resistance, an uncompensated leakage current appears that changes the matched state of the transformer core. This change is converted to a signal and fed to the output organ. This device does not respond to the symmetrical reduction of the resistance of isopl {1I and does not control the resistance of the insulation of de-energized networks. The closest to the present invention is a device for measuring the insulation resistance of DC electric networks, which are under varying voltage. It is equipped with a converter on a toroidal heart (2 ke, to the input winding of coils), the generator of quenching oscillations is connected, and the output | on the winding through the narrow-band phiplr connected to the indicator. An auxiliary source of DC voltage through a switch controlled by a synchronizer is connected to one of the poles of the monitored network using a limiting resistance. This device allows you to measure the insulation resistance only in networks with a small pole capacity in a very light ground (single microfarad). With capacitance poles of ten and hundreds of microfarads (ship's direct current networks have arcing suppressors of 100,500 microfarads) at the moments of switching the auxiliary voltage field from the pulses of current recharging of these capacitors. They are transformed into a converter core, remagnetizing it, which is the cause of the error and the occurrence of a foot signal when reading information from the core. The circuit of the invention is to improve the accuracy of measurements in networks with a poles capacitance. The circuit is achieved by qTO into a device for measuring the insulation resistance of electrical networks of direct current containing an auxiliary source of constant voltage connected through a switch and the limiting resistance to one of terminals of the controlled network, a synchronizer, a damped oscillator, connected to the input winding of the converter, as well as an extension of 4 liters and an indicator, where the output of the synchronizer is connected control switch input, a series-connected delay element and an OR element and an analog switch connected by the output winding of the converter and a narrow-band filter are inputted, with the input of the delay element and the second input of the OR element connected to the synchronizer output and the control input of the analog key to the delay element output . FIG. 1 shows a diagram of the proposed device; in fig. 2 - timing diagrams explaining the operation of the device Auxiliary source 1 of constant voltage through switch 2, operated by synchronizer 3, is connected to one of the pins of the controlled network 4 through limiting resistance 5. The switch is controlled at sufficient intervals For recharging capacity 6,7. network switches the polarity of the auxiliary voltage. The toroidal core of converter 8 is affected by packets of damped oscillations produced by generator 9, which is triggered by synchronizer 3 through an I7SH circuit 10 or through a delay element 11 and an OR circuit 10. The delay element shifts the trigger signal by the duration of the packet of damped oscillations. V When passing the first packet of damped oscillations, the false information recorded in the Moment of the previous switching of the auxiliary voltage is erased from the core of the transducer, and the true information on the state of the insulation is recorded. In this case, the voltage induced in the output winding is not transmitted by the key 12 to the narrow-band filter 13. At the moment the second packet of damped oscillations arrives, the true information on the insulation resistance is read from the core of the converter 8 and highlighted by the narrow-band filter proportional to the useful value the measured current, and, therefore, the insulation resistance value 14, 15. The voltage extracted by the narrow-band filter goes to the indicator 16. Passage authorization of the output signal from the transducer coil is accomplished by supplying a signal output from delay element 11 to input upravp conductive analog switch 12 connected between the output winding of the transformer and a narrowband filter. From the foregoing it follows that in the proposed device, when leakage current is monitored through an insulation in networks with large pole capacitances, the measurement error due to a partial change in the magnetic state of the converter cores from the current recharge pulses of the capacitances marriages are excluded. The use of new elements — the OR scheme, the delay element and the key — favorably distinguishes the proposed device from the prototype, since the influence of the network poles of the network on the measurement results is eliminated and the measurement accuracy is improved. This broadens the scope of application of the device for virtually any DC electrical networks (the capacity of the poles of which does not exceed 800 microfarads). Claims An apparatus for measuring the insulation resistance of a DC electric network, comprising an auxiliary source of DC voltage, connected via a switch and a limiting resistance to one of the terminals of the monitored network, a synchronizer, a damped oscillator connected to the input winding of the converter, and also a narrowband filter and indicator, where the output of the synchronizer is connected to the control input of the switch, characterized in that, in order to improve the accuracy of It has been developed in networks with a large capacitance of poles, a series-connected delay element and an OR element and an analog switch, included, between the output winding of the converter and a narrow-band filter, with the input of the delay element and the second input of the OR element; Analog key control input to the delay element output.

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Claims (1)

claims (capacity 800 microfarads). A device for measuring the insulation resistance of electric DC networks, containing an auxiliary DC voltage source connected through a switch and limiting resistance to one of the terminals of the controlled network, a synchronizer, a damped oscillator connected to the input winding of the converter, as well as a narrow-band filter and indicator moreover, the synchronizer output is connected to the control input of the switch, characterized in that, in order to improve the accuracy of measurements in-! With a large capacity of poles, a delay element and an OR element and an analog key connected between the output winding of the converter and a narrow-band filter are inserted into it, the input of the delay element and the second input of the OR element connected to the output of the synchronizer, and the control input of the analog key _ to delay element output.