RU1774452C - Dc electric drive - Google Patents

Abstract

Usage: in general industrial mechanisms made according to the GD system. The essence is that when the insulation is degraded, the leakage current increases and when a limit value is reached at the output of the nonlinear element with dead zone 18, a signal appears. Feedback on the leakage current comes into operation, which leads to a decrease in the voltage at the output of the generator 1. With further deterioration of the insulation, the voltage of the generator decreases and, as soon as it reaches the limit value at the output of the relay element 14, a signal appears that through element And 15 disables the drive system. 1 ill.

Description

The invention relates to electrical engineering and can be used in systems of controlled electric drive of direct current, general industrial mechanisms made according to the G-D or TP-D system, and can be used in electric drives of crane mechanisms, vertical and inclined shaft hoisting installations.

The aim of the invention is to increase the reliability and safety of operation by automatically reducing the voltage of the generator as a function of the leakage current.

The drawing shows a diagram of an electric drive.

The electric drive contains a DC generator 1 with a motor 2 connected in series, parallel to the core of which a voltage sensor 3 is connected, the first output of the voltage sensor 3 is connected to the input of the adder 4, which through the voltage regulator 5, the exciter of the generator 6 is connected to the excitation winding 7 , leakage current sensor 8, diodes 9 and 10, resistors 11 and 12, first 13 and second 14 relay elements with adjustable zone

insensitivity and limitation, logic element And 15, block 16 signaling the limit value of the leakage current, shutdown block 17, non-linear element 18. Moreover, the diodes by the anodes are connected respectively to the terminals of the motor 2, the input of the leakage current sensor 8 is connected to the midpoint of the series-connected resistors.

The input of the nonlinear element 18 with deadband and restriction is connected to the first output of the leakage current sensor 8. and the first output is connected to the input of the alarm unit 16. The first input of the first relay element 13 is connected to the second output of the leakage current sensor 8, and the second input of this element is connected to the block setting current setpoint 1lim.add., the first input of the second relay element 14 - with the second output of the voltage sensor 3, the second input - with the unit for setting the voltage setting of the generator Ui-pre. output - with the first input of AND gate 15, the second input of which is connected with the output of the first relay

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element 13, and the output is connected to shutdown unit 17.

The electric drive operates as follows. Under conditions of normal operation of electrical equipment corresponding to the maximum voltage values of the generator, the leakage current must not exceed the permissible value of u.sup. For leakage currents. due to the presence of a non-linear element with a dead zone 18 included in the feedback circuit, there is no signal at the output of this element and the leakage current feedback does not work. As the insulation deteriorates, the leakage current increases and, as soon as it reaches the value of u.s. the operating point of the nonlinear element 18 is shifted to a linear portion of its characteristic. As a result, a voltage proportional to the leakage current appears at the output of this element. On adder 4, this voltage is subtracted from the reference voltage and as a result, the voltage at the output of generator 1 decreases, reducing the leakage current to the required safe value. At the same time, a signal is sent from the second output of the non-linear element 18 to the signaling unit 16, a signal lights up, indicating that the leakage current has reached the permissible value, and the electric drive is operating at a reduced voltage of the generator. With further deterioration of the insulation, the voltage at the output of the generator 1 continues to decrease automatically, and as soon as it reaches the limit value Ui-limit. at the output of the second relay element 1 with an adjustable deadband, a signal appears that acts on the first input of the logic element And 15. At the same time, when the leakage current ly 1 u.red.add. at the output of the first relay element 14c with an adjustable deadband, a signal appears which is supplied to the second input of the logic element And 15. As a result, the protection device is activated and the electric drive is turned off, and an alarm is triggered.

Claims (1)

SUMMARY OF THE INVENTION A dc electric drive comprising a dc generator with a series-connected motor, parallel to the core of which a voltage sensor is connected, the output of which is connected to the input of the adder, the output of the adder through a series-connected voltage regulator, an exciter connected to the excitation winding of the generator, two series-connected resistors connected in parallel to the motor core, characterized in that, in order to increase reliability and security in operation by automatically reducing the voltage of the generator as a function of leakage current, two diodes are additionally introduced into the electric drive, connected by anodes to the terminals of the motor core, a sensor leakage current, the input of which is connected to the midpoint of the connection of the resistors, as well as the first and second relay elements with adjustable deadband and restriction with one output and two inputs, logic element And, block signaling the limit value of the leakage current, shutdown block, setting blocks of the current setting and voltages and non-linear element with deadband and restriction, the input of which is connected to the first output of the leakage current sensor, and the first output to the adder, the second output of this element to the input of the alarm unit, the first input of the first relay element is connected to the second output of the leakage current sensor, the second input of which is connected to the unit for setting the setpoint current equal to the maximum permissible value of the leakage current u.pred.dop, the first input of the second relay of the element is connected to the second output of the voltage sensor, and the second input is connected to the unit for setting the generator voltage setting equal to the limit value Ui-.limit, and the output is connected to the first input of the AND gate, the second input of which is connected to the output of the first relay element and the output is connected to a trip unit. V