RU2697870C2 - Method and system of remote switching of load in measuring resistance of insulation and variant of device therefor - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: invention relates to the control of the parameters of electrical equipment and electrical networks, in particular to the provision of the possibility of carrying out work to measure the insulation resistance of electrical networks and electrical wiring. Method of remote power supply disconnection consists in equipping the electric receiver with a switching device, capable of remotely disconnecting the electrical receiver for the time required to conduct insulation resistance measurements. Remotely controlled switchgear is installed between the mains and the electric receiver. Switching device switches off the electric receiver when the control voltage is applied, the frequency, the level, shape of which differs from the nominal voltage supplying the power receiver. Electric receiver is connected through normally closed relay contacts, the ballast capacitors are connected to the normally closed relay contacts on the side of the electric receiver, the second ends of the ballast capacitors are connected to the input of the diode bridge, and to the output of the diode bridge is connected the winding of the relay and the storage capacitor and/or ionistor.

EFFECT: technical result: improved reliability of the operation of distribution networks, reduced labor input in conducting insulation resistance measurements, and improved safety at the facilities of the electric economy.

6 cl, 2 dwg

Description

Technical field

The claimed invention relates to electric power devices and is intended for use in distribution networks and electrical wiring, with the aim of reducing labor costs when conducting tests for insulation strength.

State of the art

In accordance with the "Rules for the Technical Operation of Consumer Electrical Installations" for reliable and safe operation of electric networks, the program for pre-start and periodic testing provides for measuring the insulation resistance, based on which it is concluded that the networks are suitable for further operation.

The method of measuring the insulation resistance provides for measuring the resistance between the conductors: phase - ground, neutral - earth, phase - phase (with multiphase power), phase - neutral. To perform measurements of the insulation resistance phase - phase, phase - neutral, disconnection of the load is required, otherwise the measurement will not be correct, because load resistance is several orders of magnitude less than insulation resistance.

When conducting measurements of insulation resistance at small objects, there are no special difficulties, because electrical appliances are nearby and there are usually no problems with access to them.

When conducting measurements of insulation resistance at large objects, such as kindergartens, schools, hospitals, shopping centers, large administrative buildings, etc., serious difficulties arise when disconnecting electrical appliances, especially lamps, from the tested network. The complexity of these works is very large and leads to the fact that the design of test reports occurs without actual measurements of the insulation resistance between the conductors to which the load is connected. This, in turn, leads to the possibility of fire since current protection devices are not able to detect and react leakage currents between working conductors.

The technical task of the claimed invention is the simplest, cheapest and most reliable technical solution that allows you to remotely disconnect the load from the network in which you need to measure the insulation resistance, which can be easily integrated into existing, especially lighting, networks with minimal cost.

SUMMARY OF THE INVENTION

In electrical networks with a large number of power receivers, a device is installed on each of them or in a group, which includes a remotely controlled switching device with a power and control circuit, which, on command, disconnects the power receiver from the supply network. In the initial state, the system does not affect the operation of the power receiver. The disconnection takes place for the time necessary to measure the insulation resistance of the supply line, while measures are taken to exclude the effect on the measurement results. The shutdown command can be the supply of a frequency to the voltage line being tested, a level whose shape differs from the nominal voltage supplying the power receiver. After performing the required tests, the system automatically (and in some cases by command) returns to the initial mode.

One possible embodiment of the invention is the circuit shown in FIG. one.

Where is the device 1 that disconnects the power receiver 2 from the mains.

Effect: increasing the reliability of the operation of distribution networks, reducing the complexity when measuring insulation resistance, improving security at electrical facilities.

The technical result is achieved by equipping the electric receivers with a remotely controlled switching device, which, on command, turns off the electric receiver for the time required to measure the insulation resistance of the supply line.

The implementation of the invention

One possible embodiment of the invention is shown in FIG. 2 and consists in the following: The device for remote shutdown of the power receiver consists of ballast capacitors C1 and C2, a diode bridge VD1, a storage capacitor and, or an ionistor C3, relay K1 with normally closed contacts. When the device is connected to the mains voltage through the normally closed contacts of the relay K1 is supplied to the load. In view of the small capacitance (and as a consequence of the large reactance) of the ballast capacitors C1 and C2 and bypassing of the capacitor C3 by the coil of relay K1, the relay K1 does not operate. When a voltage of a higher frequency is applied instead of the operating voltage of the industrial frequency, the capacitor C3 starts charging, because the reactance of the ballast capacitors C1 and C2 to the high-frequency current is significantly less. To reduce the effect of shunting the control voltage by the load, the level of control voltage is selected significantly less than the operating voltage. The voltage at the storage capacitor C3 begins to increase to a level sufficient for the relay K1 to operate. When activated, the relay K1 disconnects the device and the power receiver from the network with its contacts and remains in this state until the storage capacitor C3 is discharged and the relay returns to its original state.

If it is necessary to identify a specific electric receiver and, or a group of electric receivers in which a violation of insulation is possible, the system and its devices can be equipped with addressable trip elements when a corresponding command is issued.

It was experimentally established that in the case of using a relay with a rated winding voltage of 5 volts, a winding resistance of about 400 Ohms and a storage capacitor (ionistor) capacity of 0.47 Farad, the relay holding time is approximately 4 minutes. This time is enough for measuring the insulation resistance between the working wires (zero and phase) of the supply line.

Used Books

"Rules for the Technical Operation of Consumer Electrical Installations."

Claims (6)

1. A method for remotely disconnecting an electric receiver, which consists in equipping the electric receiver with a switching device capable of remotely disconnecting the electric receiver from the network for the time required to measure the insulation resistance, characterized in that a control voltage, frequency, level, shape of which differs from the nominal voltage supplying the power receiver, while the power receiver is connected through normally closed relay contacts, ballast capacitors are connected to normally closed relay contacts on the side of the power receiver, the second ends of the ballast capacitors are connected to the input of the diode bridge, and the relay winding and the storage capacitor and / or ionizer are connected to the output of the diode bridge. 2. The method according to p. 1, characterized in that the command to turn off the power is supplied to the line under test, which is connected to the power and switching device. 3. A device for remote shutdown of an electric receiver, consisting of at least one remotely controlled switching device installed between the mains and the electric receiver, capable of disconnecting the electric receiver from the network for the time required to measure the insulation resistance, characterized in that the switching device disconnects the electric receiver when the control voltage is applied , frequency, level, the form of which differs from the nominal voltage supplying the power receiver, while the receiver is connected through normally closed relay contacts, the ballast capacitors are connected to the normally closed relay contacts on the side of the electrical receiver, the second ends of the ballast capacitors are connected to the input of the diode bridge, and the relay coil and the storage capacitor and / or ionizer are connected to the output of the diode bridge. 4. The device according to claim 3, characterized in that the command to turn off the power receiver (s) is sent to the line under test, to which the device and the power receiver (s) are connected. 5. The device according to p. 3, characterized in that it is equipped with elements of addressable disconnection of the power receiver (s) and / or sections of the supply line. 6. The device according to p. 3, characterized in that the switching device receives power from the mains voltage.

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