SU1663684A1 - Device for protection of submersible motor with two or more phase windings from abnormal operation - Google Patents

Abstract

The invention relates to electrical engineering and can be used to protect an electric motor powered by a multi-phase AC mains. The purpose of the invention is to increase reliability by determining the cause of the abnormal mode. When an anomalous mode occurs, for example, asymmetry of phase voltages, the latter will contain, respectively, pulses in magnitude greater and smaller than the settings from the outputs of the threshold elements 7, 8 to the inputs of converters 9, 10 of a serial digital code to a parallel one. The pulses of the clock generator 17 carry out a digit shift of the digital signal in the 9, 10 converters. When a pulse appears at the output of the polling cycle forming element 15, the comparator unit 11 reads the digital words from the code converters 9 and 10, which after comparison with the previously set digital words of the normal mode and their mismatch the comparison unit 11 forms the corresponding symbol on the display unit 12, and on the programmable timer 13 a digital code is issued for the required shutdown time motor 1. 1 Il.

Description

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The setting is larger and smaller than the settings from the outputs of the threshold elements 7.8 to the inputs of converters 9, 10 of a serial digital code into a parallel one. The pulses of the clock generator 14 carry out a digital shift of the digital signal in the converters 9 and 10 of the code. When a pulse appears at the output of the polling cycle forming element 15 by the comparison unit 11,

The invention relates to electrical engineering, is intended to protect submersible electric motors from abnormal modes, and can be used to protect electrical installations powered from a multi-phase AC mains.

The purpose of the invention is to increase reliability by determining the causes of the abnormal mode.

Fig.1 shows the scheme of the proposed device; Fig. 2 illustrates an example of the formation of digital state words in normal and asymmetric modes of operation.

The protection device of the submersible electric motor 1 contains a converter 2 of voltages (currents, power) of each phase into a total ripple voltage connected to the mains through the power contacts 3 of the switching apparatus, to the control unit 4 of which the output of the shaping device 5 of the control signals of the switching apparatus and the input of the unit are connected 6 clock generation.

The output of the converter 2 voltages of each phase is connected to the first and second threshold elements 7 and 8, the outputs of which are connected respectively with the inputs of the converters 9 and 10 of the serial digital code to the parallel one, the parallel outputs of which are connected to the inputs of the comparison unit 11 - The outputs of the comparison unit 11 are connected the display unit 12 and the programmable timer 13, the output of which is connected to the input of the driver 5 of the control signals of the switching apparatus. The clock and pulses forming unit 6 consists of a clock generator 14, the output of which is connected to the clock inputs of converters 9 and 10 of a serial digital code into a parallel one, as well as to a polling cycle forming element 15 connected to the input of the comparison unit 11.

reading digital words from converters 9 and 10 of the code, by which, after comparing with the previously set digital words of the normal mode and their mismatch, the comparison block 11 forms the corresponding symbol on the display unit 12, and the digital code of the required delay time for the electric motor 1 is output to the programmable timer 13 2 il.

Figure 2 shows: 1) a, b, c — total pulsating voltage (current, power) of phases a, b, c; Ui and Uz are voltage settings, above which pulses are formed from the output of threshold elements; 14f and 15f - signals at the outputs of the clock pulses; e ... q are the signals at the outputs of the serial digital code converters in parallel at the time of the appearance of the signal at the output of the element of the formation of the interrogation cycle, which are digital state words; 11f is the output of the comparison block per programmable timer (conventionally shown as a single pulse); 13f - programmable timer output; 5f is the output of the control driver. Submersible Motor Protection

performed as follows.

The normal mode of operation of the submersible electric motor corresponds to the same magnitude of the currents in each phase, which are in the specified range.

the settings Ui and Da of the threshold elements 8 and 7. At the output of the threshold element 7, the signals 7f are absent, and the output sequence of the threshold element 8 receives the current sequence of coincidence and mismatch of the signal with

given setpoint Ui to the input of the converter 10 of a serial digital code into a parallel one. The pulses of the clock generator 14 carry out a digital shift of the digital signal in the transducers 9 and 10 of the serial digital code to the parallel one. When a pulse appears at the output of the polling cycle forming element 15, the comparison unit 11 reads digital words from

transducers 9 and 10 of the code, which, after comparison with previously defined digital status words, determine the normal mode of operation. There is no signal for programmable timer 13, but for

the display unit 12 lights up the corresponding symbol,

When an anomalous mode occurs, for example, asymmetry of phase voltages above the allowable one, the voltage Ua.B.c contains pulses larger than the setpoint Da and less than the setpoint Ui. In this case, the process of forming digital words is similar, but the digital words themselves are different from the digital words in the normal mode. After comparing with the previously set digital words, the comparator unit 11 forms a symbol on the display unit that corresponds to the asymmetrical mode, and to the programmable timer 13, it outputs a digital code to withstand the required time to turn off the electric motor. After this time delay, the signal from the output of timer 13 is fed to the shaper 5 of the control signals of the switching apparatus, which shuts off the electric motor and the clock generator 14. The arrival of the clock pulses is stopped and the asymmetric mode symbol is stored on the display unit. Similarly, the motor is protected in other abnormal conditions.

The device allows complex protection of the submersible electric motor with a differentiated response time and memorizing the cause of the anomalous mode, which increases the reliability of the protection and extends the functionality. The device circuit can be performed entirely on digital integrated circuits, which also increases the reliability of the device and extends its functionality. For example, a three-phase single-phase rectifier can be used as a voltage converter 2; as the threshold elements 7 and 8 are comparators; converters 9 and 10 of serial serial code into parallel - shift registers or serial interfaces; Comparison unit 11 — programmable logic array or EPROM; indication unit 12 - seven-segment indicator; timer 13 - reversible counter.

The use of a microcomputer as a unit of comparison makes it possible to further extend the functionality by controlling the modes of several electric motors at once.

Claims (1)

An apparatus for protecting a submersible electric motor with two or more phase windings from an anomalous mode, comprising: switching an apparatus with terminals of power contacts intended to be connected in series to the phase wires of an electric motor; a voltage converter of each phase into a total pulsating voltage; input terminals connected to terminals for connections to the phase outputs of the motor, and the output to the inputs of the first and second threshold elements, display unit, comparison unit, photo The world of switching device control signals, whose control unit is connected to the output of the said driver, is characterized in that, in order to increase reliability by determining the cause of the anomalous mode, it is additionally equipped with two serial digital code to parallel converters, a clock pulse shaping unit, synchronized with a power supply network, and a programmable timer, with the inputs of the first and second converters of the serial digital code to parallel It is connected respectively to the outputs of the first and second threshold elements, and the outputs of serial digital code converters in parallel are connected to the inputs of the comparison unit, the outputs of which are connected to the display unit and the programmable timer, the output of which is connected to the input of the switching control signal generator unit, clock generating unit its input is connected to the output of the said driver, and the outputs to the clock inputs of the comparison unit and converters are sequentially o digital code in parallel,