SU805201A1 - Electrical circuit insulation resistance meter - Google Patents

Description

(54) DEVICE FOR MEASURING THE RESISTANCE OF ISOLATION OF ELECTRIC NETWORKS

a stopper, the first output of which is connected to the differentiation unit and a key analysis and control unit, the first and second outputs of which are connected respectively to the control inputs of the switch and the key, the third output connected to the middle output of the adjustable resistor, two voltage meters forcing the capacitor are entered , the first output of which is connected to the output of the switch, the second output to the housing (ground), potential inputs of voltage meters and two outputs of the switch are respectively connected to the phases of the monitored network, the third output is connected to an adjustable resistor, the second output of which and the second inputs of voltage meters are connected to the housing (ground), the outputs of the voltage meters and differentiation unit are connected respectively to the three inputs of the analysis and control unit, to the output of which the indicator is connected.

The drawing shows the functional scheme of the device.

The device contains voltage meters 1 and 2, switch 3, adjustable resistor 4, switch 5, forcing capacitor b, differentiation unit 7, analysis and control unit 8, and indicator 9.

The device works as follows.

After the device is connected to the network, the information about the potentials of the poles (phases) of the network comes from the outputs of meters 1 and 2 for comparison to the analysis and control unit 8, from where the command comes to switch 3 about connecting the resistor 4 to the pole (phase) of the network with higher potential . Then, block 8 issues a command to change the resistance value of resistor 4 (downwards) by the selected step. Simultaneously, from block 8, commands are periodically received from the key 5, which periodically carries out the resistor 4 bypassing the capacitor 6. Thus, a channel of forced recharging and capacitances of the network Cj (and C) 2 relative to the body is periodically created to the level determined by the ratio of the poles of the network after the first adjustment step. The voltage across the resistor 4 is continuously differentiated in block 7 and information about the derivative is fed into block 8. The periodic cycles of forced recharging and shunting of resistor 4 by capacitor 6 continue until the signal at the output of block 7 of differentiation in the pause between successive cycles does not change your sign on the reverse of that sign, which took place at the moment of time preceding this pause or in the previous pause between the CC

lamy forced reload yes. This signal blocks the possibility of CONNECTING capacitor 6. When the signal at the output of block 7 approaches the block 8, the signal 8 gives a signal at the next step of changing the value of adjustable resistor 4, and the process repeats.

This happens until the signals at the outputs of the meters 1 and 2 become equal to each other. At this time, the regulation of the resistor 4 and the periodic connection of the capacitance 6 is terminated. The value of the adjusted resistor 4, together with the originally existing potential values of the poles of the network, measured by meters 1 and 2 before connecting the adjustable resistor 4, is used to determine the insulation resistance values of the poles (phases) of the network and equivalent insulation resistance according to the formulas

"M in-0-Rp.Rp,

U -.iiii.R -.bi ::.

xg n v P

V.-Y,

n-r

 P

p,

where is r,

the value of the adjustable resistor 4 at V V potentials of the poles (phase

and VjV network relative to the body (zero bus),

insulation resistance

X2 of the corresponding poles (phases) of the network relative to the housing;

D) - the ratio of the measured potentials of the poles of the network. The obtained values, or the value of the adjusted resistor 4, are displayed on the indicator 9.

The technical and economic effect of the invention is to improve the measurement speed, which will enable one device to control more networks and feeders at the same time and more quickly detect the malfunction, and also leads to an increase in measurement accuracy, as the probability of change parameter during the measurement process itself as a result of various switching in the controlled network (connecting and disconnecting energy consumers, energy sources, etc.)

Claims (2)

Invention Formula A device for measuring the insulation resistance of electrical networks that are under voltage and have large capacitance phases relative to the body (ground), containing | INDICATOR, switch, adjustable resistor, the first output of which is connected to the differentiation unit and with the key, and the first unit and controlling the first and second outputs of which are connected respectively to the control inputs of the switch and the key, the third output is connected to the middle terminal of the controlled resistor, characterized in that, in order to increase speed and measurement accuracy, two voltage testers are inserted, forcing a capacitor, the first output of which is connected to the key output, the second output is connected to the housing (ground), the potential inputs of the voltage meters and two output switch are respectively connected to the phases of the monitored network, the third output is connected with an adjustable resistor, the second output of which and the second inputs of the voltage meters are connected to the housing (ground), the outputs of the voltage meters and the differentiation unit are connected respectively to the three inputs of the analog unit from the control to the output of which the indicator is connected. Sources of information taken into account during the examination 1. Tsapenko E, F. Control of isolation in networks up to 1000 c. M., Energie, 1972, p. 132-134. 2. USSR author's certificate number 606143, cl. q 01 R 27/18, 1975 (prototype).