RU2035047C1 - Device for quality inspection of potted rotors - Google Patents

Abstract

FIELD: electrical engineering. SUBSTANCE: invention relates to diagnostics of electric machines. Device for quality inspection of potted rotors has tested rotor 1, two transformers 2,3, two windings 4,5, magnetic field pickup 6, rectifier 7, indicator 8, sliding contact unit 9, source 10 of variable voltage. EFFECT: improved authenticity of quality inspection. 1 dwg

Description

 The invention relates to techniques for diagnosing electric machines and is intended for quality control of rotor rods of asynchronous squirrel-cage motors with open and closed slots before or after machining.

A device containing a direct current source connected through a contact node to a controlled rotor rod, an inductive magnetic field sensor of the rod and an indicator [1]
The disadvantages of this device is the low sensitivity, especially with closed grooves of the rotor, as well as the duration of the rejection.

Closest to the proposed one is a device containing two transformers, a rectifier, an alternating voltage source, an inductive magnetic field sensor, an indication unit and a sliding contact node, the input of which is connected to the rectifier output, and the primary winding of the first transformer is connected to the output of the alternating voltage source [2]
The differential signal indication block includes two voltage amplifiers with half-wave half-wave rectifiers, two filters, two potentiometers and a half-wave amplitude comparison module for the magnetic field sensor, the output signal of which is supplied to the indicator.

 However, the device has insufficient sensitivity to minor defects in the rods.

 The aim of the invention is to increase the reliability and reliability of control.

 This is achieved by the fact that in a device containing two transformers, a rectifier, an AC voltage source, an inductive magnetic field sensor, an indication unit and a sliding contact node, the input of which is connected to the output of the rectifier, and the primary winding of the first transformer is connected to the output of the AC voltage source, the first the terminal of the primary winding of the first transformer is connected to the first terminals of the inductive magnetic field sensor and the display unit, the second terminals of which are connected to the first terminal of the secondary bmotki second transformer, a second terminal which is connected to the second terminal of the primary winding of the first transformer, the secondary winding of the first transformer is connected to the input of the rectifier.

 The drawing shows the proposed device.

 The device comprises a test rotor 1, a first transformer 2, a second transformer 3, a primary 4 and a secondary 5 winding of the first transformer 2, a magnetic field sensor 6, a rectifier 7, an indication unit 8, a sliding contact node 9, an alternating voltage source 10.

 The test rotor 1 rotates around its own axis and relatively stationary sliding on the rotor rings of the contacts 9 and the sensor 6 of the magnetic field of the rod, covering one rod (horseshoe-shaped electromagnet). When the rod passes under the sensor, it is magnetized, the difference signal detected by indicator 8 is maximum, and when it is between the rods, it is minimal. The omission of the maximum with a different level of signal decline characterizes a different degree of defectiveness of the rod. This also happens when the first transformer 2 supplying the rectifier 7 is autonomous and is not connected in series to the secondary winding of the second transformer 3 of the source 10.

As a transformer 2, a current transformer is used, the primary winding 4 of which has the number of turns W ₁ >> W _{2 of the} number of turns of the winding 5. When the transformer 2 is turned on with an increase in current I ₁ through the sensor 6, as the magnetization of the rods increases the voltage drop across the winding 4, then the direct current I ₂ flowing through the test rotor 1 increases. If there is no or small magnetization of the sensor 6 from the rod (rotor tooth or rod defect), the current through the sensor 6 drops and the current I ₂ decreases. Block 8 captures the sequence of maximum and minimum values of the output signal corresponding to the passage of the sensor 6 above the rod and the tooth of the rotor 1. The signal corresponding to the defective rod has a maximum in the interval between these two levels and is proportional to the degree of defectiveness. Thus, the inclusion of the transformer 2 in series with the sensor 6 determines its role as positive current feedback. Under these conditions, it is advisable to include the differential signal indication block parallel to the sensor 6. These factors significantly increase the sensitivity of the device.

 The selection of device parameters is based on the following considerations.

To achieve maximum sensitivity, the device must be equal
I ₁ W ₃ I _c W _c , (1) where I ₁ current through the sensor 6 of the magnetic field of the rod;
W _{3 the} number of turns of the sensor 6;
I _c current through the rod;
W _{c the} number of rods covered by the sensor 6; W _c 1.

(2) где I₂ ток через испытуемый ротор в цепи выпрямителя 7;
Z₂ число стержней (пазов) испытуемого ротора.Current through the rod
I _c =

(2) where I _{2 is the} current through the test rotor in the rectifier circuit 7;
Z _{2 the} number of rods (grooves) of the tested rotor.

For current transformer 2, the ratio
K _cx I ₂ W ₂ I ₁ W ₁ , where W ₂ and W _{1 the} number of turns of the windings 5 and 4, respectively;
To _{cx the} coefficient of the rectification circuit 7 current.

(3)
Подставляя выражения (3) и (2) в (1), получают
W₃=

(4)
Преимуществом предлагаемого устройства является значительное повышение чувствительности, исключение второго источника питания и обеспечение возможности фиксации мелких дефектов стержней клетки, что позволяет исключить дефектные роторы со сборки двигателей и воздействовать на соответствующие параметры технологии заливки.Where from
I ₂ = I ₁

(3)
Substituting expressions (3) and (2) in (1), we obtain
W ₃ =

(4)
The advantage of the proposed device is a significant increase in sensitivity, the exclusion of a second power source and the possibility of fixing small defects of the cell rods, which eliminates defective rotors from the motor assembly and affects the corresponding parameters of the casting technology.

Claims (1)

 DEVICE FOR QUALITY CONTROL OF FILLED ROTORS, containing two transformers, a rectifier, an AC voltage source, an inductive magnetic field sensor, an indication unit and a sliding contact node, the input of which is connected to the output of the rectifier, and the primary winding of the first transformer is connected to the output of the AC voltage source, characterized in that, in order to increase the reliability and reliability of control, the first output of the primary winding of the first transformer is connected to the first conclusions of the inductive sensor deleterious field and display unit, the second terminals of which are connected to a first terminal of the secondary winding of the second transformer, a second terminal which is connected to the second terminal of the primary winding of the first transformer, the secondary winding of the first transformer is connected to the input of the rectifier.