JPH0888959A - Inspection device for cage rotor - Google Patents

Abstract

PURPOSE: To provide an inspection device which does away with individual differences without needing skill in judgment on whether a cage rotor is good or bad. CONSTITUTION: This inspection device is equipped with a temperature changing device 7, which gives uniform temperature change in the circumferential direction by heating or cooling one of short circuit rings 2 on both sides of a cage rotor 4, and a thermometer 9, which measures the temperature distribution during the conduction of heat to the other short circuit ring 2 through a bar 1, and it is made possible to detect that there is a defect in the bar 1 connected to the section by detecting the position where the change of temperature is slow in temperature distribution.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for inspecting the integrity of a squirrel cage rotor of an induction machine.

[0002]

2. Description of the Related Art Conventionally, electricity is applied to a bar from short-circuit rings at both ends of a squirrel-cage rotor, the voltage at each bar is measured, and the voltage balance state is checked to determine the bar's electricity. The quality of the physical connection was judged. This is called the voltage drop method.

In this voltage drop method, the current flowing from the adjacent bar through the iron core is also measured at the same time, so that the defective bar cannot be detected even if there is a defect because the voltage drop is very small. In some cases, if the rotor did not have a ventilation duct, the bar could not be inspected because the voltage on each bar could not be measured.

[0004]

Even if there is a ventilation duct, since a minute voltage difference is detected, the measurement error due to the way the probe is applied is large, requiring skill in measurement, and
With the passage of time for measurement work, the bar heats up due to energization,
As the temperature rises and its resistance changes, it may be an abnormal bar,
It was difficult to determine if it was due to the temperature rise.

An object of the present invention is to provide an inspection device which does not require skill to judge the quality of a cage rotor and eliminates individual differences.

[0006]

SUMMARY OF THE INVENTION In order to solve the above problems, the present invention provides a temperature changing device which applies a uniform temperature change in the circumferential direction by heating or cooling one side of short-circuit rings on both sides of a squirrel cage rotor. And a temperature measuring device for measuring the temperature distribution in which the temperature change changes along the bar on the short-circuit ring on the opposite side, and by detecting the position where the temperature distribution changes slowly, the bar connected to that part is detected. It is possible to detect that there is a defect in.

[0007]

Since the present invention is constituted as described above, when a uniform temperature change is applied to the short-circuit ring on one side in the circumferential direction and the distribution of the temperature transmitted to the short-circuit ring on the opposite side is measured, cuts and burrs are formed on the bar. In some cases, the temperature transmission in that part will be poor, so the temperature distribution will change compared to the part connected to a sound bar, and it will detect that the cage rotor is defective and the position of the defective bar. can do. If the change in temperature distribution is uniform, it can be seen that the cage rotor is sound.

[0008]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIG.

A basket-shaped rotor (4) having short-circuit rings (2) at both ends of a plurality of bars (1) and assembled to an iron core (3) is heated in a dish-shaped container (5) with hot water. The medium (6) is placed in a temperature changing device (7), and one side of the short-circuit ring (2) is heated uniformly. At the position corresponding to each bar (1) end of the opposite short-circuit ring (2) located above, there are multiple sensors (8) of the temperature measuring device (9).
Install along the short-circuit end.

With this structure, the temperature of the short-circuit ring (2) on one side rises via the bar (1) to the short-circuit ring (2) on the other side, but the temperature distribution of each sensor (8) is increased. Is detected by the temperature measuring device (9) connected to the sensor. In this case, all bars
If there is no defect in (1), the temperature distribution is uniform, and if there is a defect, the temperature rise of that bar is delayed compared to the temperature rise of other bars and the temperature distribution becomes non-uniform. In this case, the quality inspection can be automatically performed by setting the appropriate temperature distribution change level in the temperature measuring device in advance according to the standard of the cage rotor. Therefore, there is no individual error in the measurement, and the soundness of the cage rotor can be inspected.

In the above example, the lower short-circuit ring was heated,
Similar effects can be obtained by cooling with a refrigerant. Further, the temperature measurement and recording can be regarded as a multipoint temperature recorder or a thermal image. When a thermal imager is used, it is possible to identify a poor heat transfer location (defect) by observing the temperature change between the iron core surface and the upper short-circuit ring.

[0012]

As described above, according to the present invention,
It does not require skill to judge whether the cage rotor is good or bad, and it can be judged by measuring temperature, recording temperature or seeing it as a thermal image. In addition, even if the cage rotor does not have a duct, the cage rotor can be inspected. A device can be provided.

[Brief description of drawings]

FIG. 1 is a partially cutaway perspective view showing an inspection device for a squirrel cage rotor according to the present invention.

[Explanation of symbols]

 1 ... Bar 2 ... Short-circuit ring 3 ... Iron core 4 ... Cage-shaped rotor 5 ... Container 6 ... Heat medium 7 ... Temperature changing device 8 ... Temperature measuring device sensor 9 ... Temperature measuring device

─────────────────────────────────────────────────── ───

[Procedure amendment]

[Submission date] October 24, 1994

[Procedure Amendment 1]

[Document name to be amended] Statement

[Correction target item name] 0004

[Correction method] Change

[Correction content]

[0004]

Even if there is a ventilation duct, since a minute voltage difference is detected, the measurement error due to the way the probe is applied is large, requiring skill in measurement, and
With the passage of time for measurement work, the bar heats up due to energization,
As the temperature rises and its resistance increases, it may be an abnormal bar,
It was difficult to determine whether the resistance increased due to the temperature rise.

Claims (1)

[Claims] 1. A temperature changing device for applying a uniform temperature change in the circumferential direction by heating or cooling one side of a short-circuit ring on both sides of a squirrel cage rotor, and the temperature change is transmitted to a bar to a short-circuit ring on the opposite side. It is equipped with a temperature measuring device that measures the temperature distribution that changes with time, and by detecting the position where the temperature distribution changes slowly, it is possible to detect that there is a defect in the bar connected to that part. Inspection device for squirrel cage rotors.