RU2485534C1 - Method for determining technical condition of asynchronous induction motor in process of launch - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: in the method for determining the technical condition of an asynchronous motor in the process of launch the acceleration time is assumed as the parameter being diagnosed whereby one judges on the asynchronous electric motor technical condition. The acceleration time value will depend on the following parameters: mains voltage, current frequency, rotor inertia momentum, the motor rated speed, the motor rated power, design parameters (slot type, windings position etc), magnetic flux non-uniformity. Diagnostics is performed by way of comparing the obtained value of the acceleration time of the motor being controlled to the preset theoretical or reference value.

EFFECT: determination of the motor technical condition and evaluation of the machine performance in the capacity of the process being fulfilled.

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Description

The invention relates to electrical engineering and can be used for express control of the health of electrical machines, in particular asynchronous motors.

A known method for determining the technical condition of an induction motor according to the experience of short circuit [1].

The disadvantage of this method is that during the experiment it is necessary to achieve the symmetry of the applied voltage, due to the deviation of which large errors occur.

The closest technical solution, selected as a prototype, is the test mode at idle [2]. The tests are carried out in idle mode with a steady thermal state of the parts of the electric motor. In this case, the linear voltage between all phases, the network frequency, the linear stator current in each phase and the power consumption are measured. The test begins with a voltage equal to 130% of the nominal. During the test, 9-11 measurements are usually carried out at different line voltage values.

The disadvantage of this method is that it is impossible to determine the general condition of the electric motor, as well as its malfunction.

The objective of the invention is to provide a method for determining the technical condition of an induction motor during start-up.

The invention consists in the following. As a diagnostic indicator, the rotor acceleration time from a stationary state to a maximum (idle) speed is used. In this case, depending on the technical condition of the engine, the acceleration time increases relative to the reference.

In FIG. depicts a method for determining the technical condition of an induction motor by starting time. The acceleration time value depends on the following parameters: mains voltage; current frequency; moment of inertia of the rotor; rated engine speed; rated engine power; constructive (type of groove, arrangement of windings, etc.); uneven magnetic flux.

All of the above parameters, except for the irregularity of the magnetic flux, can be assumed constant for specific operating conditions and the make of the engine. Diagnosis is carried out by comparing the obtained value of the acceleration time of the controlled engine with a given theoretical or reference value (Fig.).

The theoretical value of the acceleration curve (curve 1) during the start-up process can be constructed using the motor passport data using a special program, and the reference value must be removed from the new electric motor. The actual acceleration curve (curve 3) is removed from the motor shaft. To do this, during start-up, the start time is monitored, and a signal is received from the engine, it is converted and fed to a computer, with the help of which a graph of the rotor speed is obtained as a function of time.

According to the data, the starting time of a new engine (reference) and an engine in operation (500 hours) differ by t = 0.0025 s. The critical value of the start time (curve 2) is set experimentally for the engines of the same type, in which the likelihood increases that during the operation of the engine an emergency occurs in which the engine fails, it is possible to designate the zone of operational state.

The actual curve of the acceleration of the motor is in the range from the reference value to the critical. Depending on the deviation of this curve from the reference value, it is possible to evaluate the state of the electric motor.

In the future, checking the engines, you can judge their technical condition, as well as predict the resource before repair or, if necessary, the decommissioning of the electric motor.

Studying the dynamics of increasing the rotor speed will not only determine the technical condition of the engine and predict its life, but also evaluate the performance of the machine and the quality of the process.

Information sources

1. Gervais G.K. Industrial testing of electrical machines: textbook. for universities / G.K. Gervais. - 4th ed., Abbr. and reslave. - L .: Energoatomizdat, 1984. - 359 p.

2. Gervais G.K. Industrial testing of electrical machines: textbook. for universities / G.K. Gervais. - 4th ed., Abbr. and reslave. - L .: Energoatomizdat, 1984. - p. 354-359 - prototype.

Claims (1)

A method for determining the technical condition of an induction motor during start-up, in which the asynchronous motor is prepared for start-up and started, characterized in that during start-up, the start time is monitored, a signal is received from the motor, it is converted and fed to a computer, by which a schedule is obtained rotor speed as a function of time, then it is compared with the schedule of a technically sound engine, according to the revealed deviations of the start-up schedule of the test engine from the start-up schedule Ki of a working engine determines the technical condition of the tested engine.