SU118896A1 - Device for measuring network insulation resistance - Google Patents

Description

The proposed device for measuring the insulation resistance of a network belongs to a known type of device of the same purpose, whose operation is based on finding equipotential points on a potentiometer connected between the wires of the network using a high-resistance measuring device.

A feature of the proposed device, which makes it possible to directly read the value of the sought resistance on the instrument scale, is the inclusion of the indicated instrument in an electrical circuit in series with an auxiliary source of direct current and a potentiometer motor connected between the wires of the network.

The use of a three-position switch in the device allows the use of a high-resistance measuring device both as a network voltmeter and as a zero indicator when measuring the insulation resistance.

FIG. Figures 1 and 2 show the electrical circuit of the proposed device in two versions.

The device includes: a potentiometer P, a sensitive high-resistance measuring device G, an auxiliary DC source (for example, a low-power stabilized rectifier) U and a switch K.

At position 1 of the switch / C (Fig. 1), a point is found on the potentiometer, the potential of which is equal to the potential of the housing (ground). This point is characterized by the absence of current through the measuring device, the needle of which remains in the initial position of the scale at the mark oo.

In position 2 of the switch, an auxiliary DC source U with a stable voltage is turned on in series with the meter.

No. 118896

The insulation resistance of the R network is determined by the sum. e. - 1 - - -. -, .jrl jr2

The complete ila scale of the measuring instrument G is determined by the value of this resistance, and this scale can be calibrated in terms of the resistance.

Since the device is designed to be turned on periodically for the measurement time, the rest of the time the measuring device can be used as a voltmeter for measuring in the network. For the device must be applied three-position switch Ki (Fig. 2). The scale of the measuring instrument in this case is calibrated in terms of voltage and resistance.

Normally, the switch Ki is in the position / and the measuring instrument G operates like a voltmeter.

To measure the insulation resistance, the switch is turned to position 2 and the potentiometer P is turned to the arrow 00. In this case, the direction of mixing of the potentiometer slider from its average position indicates which insulation of the wires (+ or -) is in the worst state. After the arrow is installed on the switch, it is transferred to the position 5 - while the arrow of the instrument G shows the resistance of the network insulation.

The device can be used to measure the insulation resistance of both DC and AC networks.

Subject invention

Claims (3)

1. A device for measuring the insulation resistance of a network, whose operation is based on finding equipotential points on a potentiometer connected between the wires of the network, using a high-resistance measuring device, is different because in order to directly measure the value of the desired resistance on the instrument scale , the latter is included in the electrical circuit in series with an auxiliary DC source and the engine of the indicated potentiometer. 2. The device according to claim 1, characterized in that, in order to use a high-resistance measuring device as a network voltmeter and a zero indicator when measuring insulation resistance, a three-position switch is used. 3. Application of the device according to claims. 1 and 2 in AC networks. and g - g Committee on Inventions and Discoveries at the Council of Ministers of the USSR Editor L. A. BlatovaGr. 95 Information and Publishing Department. Sub. to pec. 21.IV-59 Volume 0.34 p. L. Zak. 2569Care 785Price 50 kopecks Printing houses of the Committee on Inventions and Discoveries at the Council of Ministers of the USSR Moscow, Petrovka, 14. Monitored network wires Leakage resistance