SU917136A1 - Device for detecting damage of asynchronous motor short-circuited rotor rods - Google Patents

Description

(54) DEVICE FOR DETECTION OF DAMAGES OF STEM OF SHORT-CLOSED ROTOR OF ASYNCHRONOUS MOTOR

I

The invention relates to an electron measuring technique and can be used to create devices for diagnosing rotor bars of asynchronous motors ...

A device is known for monitoring damage to the rotor squirrel cage rods of an asynchronous motor in operating mode, which contains a power source, a speed sensor and an indicator 1.

The closest to the present invention is a device for detecting damage to the cores of a short-circuit: - that rotor of an induction motor containing an electromagnetic sensor, the output of which is connected to one of the decoder inputs, another input of the sensor is connected to the output of the counter, the inputs of which are connected respectively to the outputs of the spatial location sensor rotor rods a and fic. rev sator, and display unit 2.

A disadvantage of the known devices is the low accuracy of the determination of the defenses.

The purpose of the invention is to improve the accuracy of determining the solids of a squirrel-cage rotor of an asynchronous motor in the operating mode.

This goal is achieved by the fact that a device for detecting damage to rods of a short-circuited rotor asyn10 chronically engine contains an electromagnetic sensor, the output of which is connected to one of the inputs of the decoder, the other input of which is connected to the output of the counter, the inputs of which are connected respectively to the outputs of the spatial location sensor. rotor rods and latch rotations, and a display unit, equipped with an additional counter and trigger blocks and

20 elements And by the number of rods of the tested rotor, while the counting input of the additional counter is connected to the output of the latching speed, its output

connected respectively to one of the inputs of the display unit and c. the first inputs of the elements I, the outputs of which are connected to the corresponding other inputs of the display unit, the control output of which is connected respectively to the reset input of the additional counter and the first inputs of the flip-flops, the second inputs of which are connected to the corresponding outputs of the main counter, and the outputs of the flip-flops are connected respectively to the second inputs of the elements I.-.

In addition, to achieve this goal, the electromagnetic sensor is designed with a differential R S-1upyu, the output of which is connected to the output of the electromagnetic sensor.

The drawing shows a structural scheme of the device.

The device contains an electromagnetic sensor 1 with a differentiating I S-circuit, a decoder 2, a sensor 3 of the spatial arrangement of the rotor rods, a latch 4 turns, a counter 5, an additional counter 6, blocks 7 of the flip-flops, blocks of elements 8 And and block 9 of the trigger.

The device works as follows.

Sensor 1 is located near the rotor sterling. With healthy rods from each of them, an EMF pulse is induced in the coil. The differentiation of the R S -chain in sensor 1 is necessary to reduce the EMF value from the electromagnetic fields of the stator. In the decoder 2, the pulses are distributed synchronously with the signals from the sensor 3 of the spatial arrangement along the outputs, the number of which is equal to the number of rods. The latch 4 turns after each revolution resets the counter 5. Signals switching the triggers are given from the additional counter b according to the filling setpoint. After accumulating a certain number of pulses, an additional counter 6 at its output appears a signal that is fed to the inputs of elements 8 I. If there is damage on the output of element 8 And corresponding to the number of the damaged rod, the signal is. The indicator block sums up the number of broken rods, fixes their numbers, resets the additional counter 6 and switches the triggers 7 to the initial position. Multiple operation of the counter 5 is necessary because.

that the frequency of the current in the rotor bars is equal to the product t S, where 5 is the slip, and f is the frequency of the supply network. The passage of current through zero in

the rod with frequency tp will be registered by sensor 1 as its break. Every quarter of the period, the magnitude of the current in the rod reaches its maximum value. Hence the minimum required number of revolutions for one measurement is. P g, where P is the rotor speed per unit of time ..

The signal from the latch 4 turns

appears between the last and the first pulses of the sensor 3 of the spatial arrangement of the rods. This is accomplished with the aid of the latch of the latch of revolutions, which provides the necessary

Duty time reset counter 5 after each turn. This circuit works in any direction of rotation of the engine. Only the order numbers of the rods change when the direction changes.

rotation

Thus, the proposed device has the same sensitivity due to the introduction of the differentiating 45-chain, and, consequently, the increased accuracy of determining the number of damaged rods by memorizing the state of the rods for several rotor turns, which is accomplished additionally by the counter, triggers and elements with appropriate compounds.

Claims (2)

Invention Formula 40 1, Device for detecting damage to rods of a short-circuited rotor of an induction motor, comprising an electromagnetic sensor, the output of which is connected to one of the inputs of the decoder, the other input of which is connected to the output of the counter, the inputs of which are connected respectively to the outputs of the sensor of the spatial arrangement of the rotor rods and the speed lock, and the unit indicators, in order to determine the accuracy of the damaged rods of the closed-loop rotor of the induction motor in the working In the meantime, it is equipped with an additional counter and blocks of triggers and elements And the number of rods of the tested rotor, the counting input of the additional counter is connected to the output of the speed lock, its output is connected to one of the inputs of the display unit and to the first inputs of the elements And, whose outputs connected to the corresponding other inputs of the display unit, the control output of which is connected respectively to the reset input of the additional counter and to the first inputs of the flip-flops, the second inputs of which are connected with the corresponding outputs of the main counter, and the outputs of the triggers are connected Svettelsteenio with the second inputs of elements I. 2. The device according to claim 1, about tl and which is so that the electromagnetic sensor is differentiated from the differentiating RS-chain, the output of which is connected to the output of the electromagnetic darachik. Information sources, taken into account in the examination l.B.C.Gaydon andOt / l, Efectp. . 1979, 205, No. 14, p. 37-38. 2. USSR author's certificate number 333656, cl. C, O1 R 31 / OO, 1973.