RU1808165C - Device for protection of excitation winding of synchronous electric machine - Google Patents

Abstract

The essence of the invention: combining the inputs of the first and second control units and connecting them to the input of the first controlled key, as well as the second control unit in the form of p series-connected zener diodes, and the first control unit in the form of p-1 series-connected zener diodes can improve the reliability of operation - .y devices. 1 ill.

Description

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The invention relates to electrical engineering, in particular to the excitation, regulation and protection of electrical machines, and to find application for protecting the excitation winding of a synchronous machine, in particular a synchronous compensator, from overvoltages arising during start-up.

The aim of the invention is to increase the reliability of the device.

The drawing shows a diagram of the device.

The device for protecting the field winding 1 contains a rectifier 2 having inputs 3 by the number of phases of the supply voltage and connected to the field winding 1, the first 4 and second 5 start-up resistors, the first 6 and second 7 switches, each having a power 8 and a control 9 inputs and output 10, and the first 11 and second 12 control units, each of which has an input 13 and an output 14. Each

the control unit contains serially connected zener diodes 15, the second block 12 containing m zener diodes, and the first block 11 containing n zener diodes, where n 1,2, ... (t - 1). The first start-up resistor 4, the first key b, the second key 7, the second start-up resistor 5 are connected in series and connected to the excitation winding 1 with a polarity opposite to the polarity of rectifier 2, the midpoint of this circuit is connected to one of the inputs of 3 rectifier 2 The outputs 14 of the control units 11 and 12 are connected to the control inputs 9 of the keys 6 and 7, respectively, and the outputs 13 are interconnected and connected to the power input 8 of the first key 6,

The device operates as follows.

At start-up, one half-wave of the variable EMF. arising on the winding 1 excitation

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It closes through rectifier 2. After the current passes through zero, the voltage on the excitation winding 1, which turned out to be open in this mode, rises rapidly and, having reached the triggering voltage of the zener diode chains 15 of control units 11 and 12, leads to the opening of Keys 6 and 7 closing the field winding 1 to the start-up resistors 4 and 5, after this half-wave of current passes through the start-up resistors 4 and 5, the keys 6 and 7 are closed, and the process is repeated with the slip frequency. At a subsynchronous speed, the supply voltage is supplied to the inputs 3 of the rectifier 2, if at that moment the keys 6 and 7 are open, the inrush current through them is limited by the resistance of the starting-protective resistors 4 and 5. The jumper between the middle point of the protective circuit and one of the inputs 3 Rectifier 2 enables each key 6 and 7 to be shunted for currents coming from Rectifier 2, whereby the keys are closed and are not involved in further normal operation of the synchronous machine. However, when overvoltages occur on the excitation winding 1, exceeding the operation settings of the control units 11 and 12, the switches b and 7 connect the start-up resistors 4 and 5, which helps to suppress the overvoltages.

Thanks to the connected control units 11 and 12, their response threshold is determined by the maximum possible voltage in the forcing modes of the excitation winding 1, which allows the device to be kept in operation to less glides than the device provides with the control units connected to the voltage of their key. and therefore, the starting process is facilitated.

Due to the fact that the control unit 11 contains zener diodes less than the control unit 12, the key 6 is ready for operation somewhat earlier than the key 7. This ensures reliable switching on of the device by

when the voltage across the excitation winding 1 is reached equal to the threshold of the control unit 12, which results in a high performance of the device. Since current

5 of each control unit flows in its own circuit, the shunting of key control unit 11 of key b is not reflected in the current through the control unit 12 when the device is turned on. Thus, the operation mode of blocks 11 and 12

Management is facilitated, which increases the reliability of the device.

Thus, a set of distinctive features provides when using the claimed device

5 lightweight start-up of the synchronous machine at. increased reliability of the device itself by facilitating its operating modes.

Claims (1)

The claims 0 A device for protecting the excitation winding of a synchronous machine, containing a rectifier, the inputs of which are intended to be connected to the phases of the supply voltage, and the outputs are connected to the terminals of the excitation winding 5, the first resistor, the first controlled key, the second controlled are connected in series to the outputs of the rectifier switchable key and second resistor, common connection point of the first 0 and the second controlled key is connected to one of the inputs of the rectifier, to which the controlled keys are connected in the opposite polarity, the control inputs of the first and second controlled keys 5 are connected to the outputs of the first and second control units, respectively, characterized in that, in order to increase reliability, the inputs of the first and second control units are combined and connected to the input of the first controlled key, while the second control unit is made in the form of n sequentially connected zener diodes, and the first control unit is made in the form n - 1 5 series-connected zener diodes.