SU1030744A1 - Device for measuring electric network insulation resistance - Google Patents

Abstract

A DEVICE FOR MEASURING THE RESISTANCE OF ELECTRIC NETWORK INSULATION, containing an additional resistor, connected to the switch contacts between the control poles, the network and the copy, two memory blocks, an adder and a measuring unit, characterized in that, for the purpose of sensitivity, a second adder and voltage divider with two outputs, while the latter consists of two partitioned arms, which are connected between the poles of the network and the earther, and has outputs from sections connected directly enno k. earth ground, and its outputs connected to inputs of the second adder, the output of which is connected via switch contacts to blocks of memory which are connected to the outputs pervogosummatora input to the output of which is connected § measuring element. . with SAE i; i

Description

The invention relates to a measurement technique, and more specifically to the measurement of the insulation resistance under the voltage of a nocTOHiiHoro and of a constant current network with a pulse current.

1-1, devices for monitoring the resistance of the insulation of DC electric networks 13 are known.

These devices have a low sensitivity in the region of small insulation resistance values.

A device for measuring the insulation resistance of electrically DC networks is known, which contains an additional resistor, a measuring element and a switch connected to. the phases of the monitored network, the first output of the additional resistor is connected to the first and second outputs of the switch, and the second output of the additional resistor, as well as non-switched inputs of the two programming blocks are connected to the housing, the remaining inputs of the storage blocks are connected to the fifth and sixth outputs of the switch 2.

When using this device, it is possible to obtain results with great accuracy, but in networks with a low level of insulation resistance its sensitivity is not very high and, as a result, there are errors in the measurement results.

The aim of the invention is to increase the sensitivity.

The goal is achieved by the fact that a second adder and a voltage divider with two outputs, while the latter consists of two partitioned shoulders, which are connected between the poles of the network and the grounding conductor, and has outputs from sections connected directly to the grounding conductor, and its outputs us to the inputs of the second adder, the output of which is connected via switch contacts to blocks of memory which are connected to the outputs of the first input matopa cy, which is connected to the output of the measuring body,

In the drawing there is a block diagram of the proposed device.

The device contains a controlled network 1 with a working voltage V and insulation resistances R and R. network poles with respect to ground, switch 2 with two pairs of change-over contacts, additional resistor 3, voltage divider 4.

adders 5-1 and 5-2, memory blocks 6-1 and 6-2, measuring unit 7.

One pin of the additional resistor 3 is connected to the poles of the monitored network 1 through pins 2-1

(short-circuiting) and 2-2 (disconnecting switch, the second terminal of resistor 3 is connected to the grounding conductor. The input of the summing unit 5-1 is connected to the monitored network through a voltage divider, and the output through the contacts 2-3 is closed) and 2-4 ( to the output of memory blocks 6-1 and 6-2. The outputs of the memory blocks are connected to the input of the adder 5-2, from the output of which

the signal is fed to the input of the measuring body 7.

The device works as follows.

When the device is connected to a monitored network (at this position of the switch contacts as indicated in the diagram), the voltage divider 4-1 connects the voltage of V and Vg through the divider 4 to the input of the adder 5-1. ( as

they are of different polarity), which has the form

r-VV R:; R H)

This value is recorded in memory block 6-2.

s

Next, the switching of the contacts of the switch takes place, after which (according to the switching of the contacts) the signal at the output of the block is

vR-t

V-V., CR.4,) - V,

This signal is recorded in memory block 6-1, after which signals from memory blocks 6-1 and 6-2 are fed to the input of block 5-2, which performs the subtraction. signals D from D, and a voltage appears at its output, the value of which is determined by the expression.

Q

-U-a ,, - uv - v "um

1-v

R 9Kb

Where I am

is equivalent to the network isolation resistance,

those. The magnitude of the voltage at the output of the summing unit S2 is uniquely determined by the value of the equivalent insulation resistance of the network. This voltage is applied to the input to measure the l organ.

The use of the proposed device improves the accuracy of measurements in the low

310307444

insulation resistance. 20–30 times lower than the error of the known non-relations 0,., 1 error-devices based on the three-norm method of the proposed device per voltmeter readings.

Claims (1)

DEVICE FOR MEASURING RESISTANCE OF ELECTRICAL NETWORK INSULATION, containing an additional resistor connected through the switch contacts between the poles of the monitored network and the ground electrode, two memory blocks, an adder and a measuring organ, characterized in that, in order to increase the sensitivity, a second adder and divider are introduced into it voltage with two outputs, while the latter consists of two sectioned arms that are connected between the poles of the network and the ground electrode, and has outputs from sections connected directly about to the ground electrode, and its outputs are connected to the inputs of the second adder, the output of which is connected via the switch contacts to memory blocks, to the outputs of which the input of the first adder is connected, to the output of which § measuring body