SU34078A1 - Device for measuring ground resistance - Google Patents

Description

The proposed method for measuring the grounding resistance is based on the use of a two-frame magnet | 1-electric ohmmeter without a guide moment. This device indicates directly the relationship of currents in, its frames. Measurement is carried out according to the voltmeter and ammeter method. Measurement of the grounding resistance must be carried out using alternating current in order to eliminate the effect of e. d. polarization, which can exist between individual electrodes.

On the attached drawing shows a diagram of the device.

The circuit provides power from the AC inductor JO in such a way that — through the test earthing X and the auxiliary probes A and B, the alternating current passes. In such a case, the application of the magnetoelectric device O becomes possible only if the alternating current is rectified. The rectification is carried out with the help of copper-oxide or iron-selenium dry rectifiers 5, 6, 7 and 8, Rectifiers are turned on so as to maintain the alternating current in the ground circuit and pass constant through frames 7 and 2 of the device O. Frame 7 is the current frame, and the 2-raccon frame voltage.

(350) i /

The voltmeter circuit has a large resistance, determined mainly by the additional resistance 9. This requires ji3 considerations for increasing the accuracy of nptti6opa and the independence of its readings on the resistance value of the auxiliary probe A.

The inductor voltage should be chosen as large as possible, having in mind the additional decrease in the error caused by the electromotive force of polarization.

To increase the measurement limits to the current frame, a / 7 shunt is introduced. The resistance of 3 hours 4 in the case of the use of a two-frame device is used to compensate for the resistances of the frames in the circuit of rectifiers 6 and 7 t in order to preserve the possibly undistorted shape of the current flow through the earth.

To completely eliminate the effect of e. d. polarization instead of resistances .3 and 4, additional windings can be applied, wound on frames / and 2 and turned off so that the fields created by them fold in pairs with the fields of windings 7 and 2, i.e. 7 and 5 and 2 VL 4. Such a scheme, in addition, will lead to an increase in the sensitivity of the device.

Use of the device is possible only if the auxiliary probes A and S are assigned to sufficient

a large distance from the earth under study and from each other (a distance of about 25-50 meters).

Subject izotrette either.

1. An I31 non-earth grounding device, according to the method of determining current and voltage, using two auxiliary earthing, one of which is connected to the main circuit and the other to the circuit of the measured voltage is different In order to supply the measuring device with the rectified current while maintaining the alternating current 8, the grounding circuits used included in pairs parallel and opposite to each other rectifiers 5, 7 nb, 8, of which rectifiers b and 7 are included

each with one of the windings I, 2 is a device measuring the ratio of currents, and rectifiers 5 are in series with 3 h 4 resistances shunting each one from the framework of the device and intended to preserve the undistorted form of the AC curve in the common circuit by compensating (Ui influenced by the main winding /, 2 devices.

2. Modification of the device according to claim 1, characterized in that the resistances 3 VI 4 are replaced by additional windings located respectively on paMkax 7 and 2 of the moving system of the device and switched on in such a way that the fields they create fold in pairs with the fields of the main windings I, 2 in order to increase the sensitivity of the device.