SU1404983A1 - Method of checking insulation resistance - Google Patents

Abstract

The invention can be used to control insulation resistance, mainly electrical objects. Capacitance of the object of control from an alternating current circuit of an industrial frequency is charged. The charge flowing through the insulation resistance for one period of the industrial frequency over the area under the curve of the current pulse that restores the charge capacity of the test object is measured. The magnitude of the measured charge determines the value of the insulation resistance. In the description of the invention, a device is considered, a real method, and timing diagrams of the measured current and voltage are given. The method reduces the time control. 2 Il. with S C / s

Description

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er

The invention relates to instrumentation technology and can be used to control the resistance of an electrical object to its insulation.

The purpose of the invention is to reduce the monitoring time by measuring the magnitude of the Hbs charge for one period of industrial frequency,

FIG. 1 shows a device that implements the proposed method; Fig. 2 shows time diagrams of the measured current and the voltage of the source.

The device contains a switch 1 unipolar key 2 J control unit 3 control unit 4 delay control unit 5, current transformer 6, industrial frequency source 7, insulation resistance 8 and control object 9, terminal 10 for connecting the control object. Moreover, the first output of source 7 is connected to the inputs of key 2 and control unit 3, the first output of which is connected to the control input of switch 2, the output of the latter is connected to terminal 10 via the primary winding of the transformer 6, the secondary winding of which is connected to the first input of the unit 5, the second the input of which is connected to the output of block 4, the input of which is connected to the second output of block 3,

Insulation resistance monitoring is performed as follows.

After switching on the switch 1, the source voltage is applied to the key 2 and transmitted to the control unit 3, which, when the voltage drops to zero, gives the command to unlock the key 2, This occurs at the time t, the current pulse passes into the control circuit i ,, the charging capacitance 9 of the insulation to the amplitude value of the voltage of source 7, the controlled insulation system acquires a charge

Q ist.monns L-b)

0

five

0

a charge of Q during a time t - t ,, equal to a period of 50 Hz, is

7.0.10

Pure yist, where t,

 “Ñ-С„,) (,)

H is the time of the beginning and end of the current charge of capacitance 9, respectively.

A sinusoidally varying voltage source and. (t) exceeds the voltage on the insulation capacitor I. through the reducing charge of the monitored insulation system to the level of the initial charge.

Unit 4 delays the permission to receive the signal by unit 5 from transformer 6 for the time of initial charging of the insulation capacitance t - t,,

Block 5 determines the resistance level of the monitored insulation under the curve of the current pulse i,

The ability to control the flowing part of the charge, which determines the insulation resistance, by the impulse of the reducing current charge is determined by the dependence

q j 1, (t) -dt (2)

 tj

Using dependencies (2) and (1) determine the insulation resistance value of the test object,

Claims (1)

5 claims 0 five The method of controlling the insulation resistance, which means that the capacitance of the test object is charged, measures the charge flowing through the insulation resistance of the test object and determines the insulation resistance value, which is control time by measuring the magnitude of the charge for one period of the industrial frequency, charge the capacity of the control object from the network where Y, is the amplitude value of the industrial frequency current,. source 7, and the measurement of the charge flowing After the voltage of the source is due to the insulation resistance, the prod- uct 7 will decrease below its amplitude w the total value of U, ist Max capacity 9 It takes time t. Thus, the part q of the initial frequency that flows down over the area under the curve of the current pulse that restores the charge of the control object.  vtf i / cm. f / 3i  ifff Sh FIG.