SU1312495A1 - Device for measuring specific resistance of ground - Google Patents

Abstract

This invention relates to electrical instrumentation used for electrical safety. The goal is to increase the measurement accuracy of the resistivity of the soil in complex geological conditions and simplify the measurement process. This is achieved by arranging the pin vertical probes - electrodes 4 arranged coaxially relative to the central probe - electrode 5, which has a measuring conductive zone (HMI) two security zones with height a and b, with this, the lateral surface area of the CID on the central probe-electrode 5 is equal to the guard zone with height a, and the guard zone with height b is 0.7-0.8 square adi shz. 2 Il. (L –E

Description

The invention relates to an instrumentation technique applied in the field of electrical safety and can be widely used in determining the actual values of the soil resistivity for calculating, designing and executing protective circuits of electrical installations.

The aim of the invention is to improve the measurement accuracy in complex geological conditions by eliminating measurement errors due to redistribution and changing electric fields in the ground, reducing errors caused by deviations of the electrodes from the vertical position and deviations from the specified distance between the electrodes. This is because, due to the radial arrangement of the measuring electrodes, the averaged value of the resistivity of the soil is already measured.

Fig, 1 shows the block diagram of the device; in fig. 2 is an electrode layout diagram;

The device contains an alternating voltage generator 1 connected through an isolating transformer 2 to the diagonal of the measuring bridge, formed by constant resistance 3, ground resistance between radially located pin-w vertical side probes-electrodes 4, driven into the ground at the test site, and a central probe -electrode 5 with a measuring conductive zone h and two guard zones with a height of a and b, a constant resistance of 6 and a compensating resistor 7 with a scale of reference; in units of soil resistivity. In the second diagonal of the measuring bridge, a zero indicator 8 is included. The guard zones of the central probe electrode 5 are connected via a balancing constant resistance 9 and 10 to the common cable of the transformer 2 and constant resistance 3 and 6,

The device works as follows.

According to the zero-indicator 8, the operator, changing the resistance of the reich, 7, balances the bridge and counts on the scale of the reichord 7, the resistivity of the soil located in the interelectrode O

Mr. space. Due to the coaxial arrangement of the probe electrodes, the shape of the electric field inside the structure of the electrodes in the horizontal plane is radial. This eliminates the effect of nearby 1x random inclusions, in particular, stones placed in the soil layer near the probe-electrode electrodes, metal structures, etc. The presence of two security zones symmetrically located in height relative to the measuring zone on the central electrode allows to obtain a uniform vertical electric field in the measurement zone. This eliminates the error from the effects of the upper layer of soil (bulk or natural, for example, the upper layer of chernozem), as well as from the high-lying overmoistened lower layers. As a result, the current in the measuring zone passes only through a layer of soil, which is not measured, and the choice of the area of the second guard zone within 0.7-0.8 square meters will be measured by the first and guard zone dictated by the goal of reducing the impact -. effects on uniformity

five

0

thirty

floor in the measuring area. This ratio is chosen experimentally.

five

Claims (1)

Invention Formula A device for measuring soil resistivity, containing vertical stubby probes-electrodes connected to an ac measuring bridge, "characterized in that, in order to improve measurement accuracy in complex geological conditions and to simplify the measurement process, vertical stub probes-electrodes placed coaxially relative5 0 five but the central probe electrode containing in the middle part a measuring conductive zone and two guard zones located symmetrically with respect to this zone, the side surface area of the measuring zone on the central probe electrode being equal to the first guard zone, and the second guard zone being 0.7-0.8 of the area of the measuring zone, while the protection zones are connected to one of the nodes of the powered diagonal of the bridge through balun resistors. Editor G. Volkova Compiled by N. Mikhalev Tehred L. Serdyukova Order 1969/44 Circulation 731. Subscription VNIIPI USSR State Committee for Inventions and Discoveries 113035, Moscow, Zh-35, Raushsk nab., 4/5 Production and printing company, Uzhgorod, Projecto st., 4 9us. S Corrector S.Cherni.