JPS61151484A - Apparatus for diagnosis of electromotor - Google Patents

Abstract

PURPOSE:To provide an electromotor diagnosis apparatus capable of performing not only accurate diagnosis by quantitatively judging the layer short, disconnection of slackening of a stator coil but also easy tendency control with the elapse of time. CONSTITUTION:A phase non-equilibrium ratio and an amplitude non-equilibrium ratio changing by the abnormal degree of the stator coil of a three-phase electro motor 1 are calculated while the data of the phase non-equilibrium ratio and the amplitude non-equilibrium ratio calculated at every predetermined period are successively stored in second memory 16 and the data of the phase non- equilibrium ratio and the amplitude non-equilibrium ratio stored in the second memory 16 are subjected to data processing to be displayed on a graphic display device 19. As a result, the advance state of the abnormality of the stator coil of the three-phase electromotor 1 can be quantitatively displayed and the diagno sis of the stator coil can be accurately performed without an indivisual differ ence and tendency control can be also performed.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application This invention can determine whether there is a layer short circuit, disconnection, or looseness in the stator coil of a three-phase induction motor, or whether there is a layer coat, disconnection, or looseness in the rotor coil. The present invention relates to a motor diagnostic device that can diagnose abnormalities such as disconnection of rotor bars.

Conventional technology Layer shorts and stator coil loosening caused by dielectric breakdown in the stake coils of three-phase induction motors are caused by
Since this is directly linked to the lifespan of the phase induction motor, it is necessary to periodically diagnose its presence or absence and strive for early detection.

To diagnose layer shorts, looseness, etc. of the stator coil of a three-phase induction motor, observe the current waveform of each phase during rotation of the three-phase induction motor with an oscilloscope, record it with a Visigraph, etc., and use these observations and recorded results. Based on this, the inspector determines the presence or absence of layer short-circuit loosening (degree of interlayer dielectric breakdown). Specifically, the presence or absence of layer short-circuiting, loosening, etc. is determined by utilizing the fact that when layer short-circuiting, loosening, etc. occur in the stator coil, the current waveforms of each phase become unbalanced.

On the other hand, if a disconnection or layer short occurs in the rotor coil or rotor bar of a three-phase induction motor, smooth rotation will not be obtained and a serious failure will occur, so it is necessary to detect rotor abnormalities at an early stage.

For this reason, the current waveform of one phase of the rotating rotor coil is observed using an oscilloscope, and based on the observation results, an inspector determines whether the rotor is normal or abnormal. That is,
When an abnormality occurs in the rotor, the detected waveform differs from the normal one, which is used to determine whether the motor is normal or abnormal.

Problems to be Solved by the Invention In the stator coil diagnostic method described above, it is difficult to quantify the criteria for determining the presence or absence of layer shorts and loosening, and the determination must rely on the experience and intuition of the inspector. There was a problem in that there was considerable variation among individual patients, making it difficult to make accurate diagnoses.

Additionally, in order to monitor the progress of abnormalities in three-phase induction motors, it is necessary to manage trends over time, but conventionally, diagnosis has been based on the experience and intuition of inspectors, making the above trend management extremely difficult. Met.

On the other hand, in the case of rotor diagnosis, it is difficult to quantify the criteria for determining normality and abnormality, and the judgment is based on the experience and intuition of the inspector, which has the same problem as stator coil diagnosis that it lacks accuracy. Furthermore, trend management has been extremely difficult when diagnosing rotor coil abnormalities.

The object of the first invention is to quantitatively determine layer short-circuit breakage, loosening, etc. of a stator coil and to make an accurate diagnosis, and to easily manage trends over time. It is an object of the second invention to provide an electric motor diagnostic device that can quantitatively determine whether a rotor is normal or abnormal and perform accurate diagnosis, and also easily manage trends over time. The object of the present invention is to provide a motor diagnostic device that can perform the following steps.

Means for Solving the Problems As shown in FIG. 1(A), the motor diagnostic device of the first invention includes a current detector (
a current transformer 2.3), an A/D converter 8.9 that A/D converts the output of the current detector (2, 3), and a waveform output from the A/D converters 8, 9; Collect data and memory 1
3, a phase difference calculation means 12B for calculating the phase difference between each phase current from the waveform data stored in the first memory 13, and an amplitude calculation unit 12B for calculating the amplitude of the first current. stage 12C, phase unbalance rate calculating means 12D which calculates a phase unbalance rate from the difference between the maximum and minimum phase difference of each phase current calculated by the phase difference calculating means 12B, and the amplitude calculating means 12C. An amplitude unbalance rate calculating means 12E for calculating an amplitude unbalance rate from the difference between the maximum and minimum amplitude of each phase current, a graphic display 19, and the phase unbalance rate calculating means 12.
a second data collecting means 12F that sequentially stores the calculation results in the second memory 16 each time the amplitude unbalance rate calculation means 12E outputs the calculation results; and the second memory 16.
data processing means a (to) for graphically displaying the plurality of calculation results stored in the graphic display 19;
The present invention is characterized by having a configuration including the following.

As shown in FIG. 1(B), the motor diagnostic device of the second invention includes a current detector (
2), a rotation detector 6 for detecting the rotation of the three-phase electric motor l, an A/D converter 8 for A/D converting the output of the current detector, and a rotation detector 6 for detecting the rotation of the three-phase motor l; a rotation speed calculation means 12G for calculating the rotation speed of the phase motor 1;
A first data collecting means 12A that collects waveform data output from the D converter 8 and stores it in a first memory 13, and performs frequency analysis based on the waveform data stored in the first memory 13. a frequency analysis means 12H for calculating the power spectrum, a beat frequency calculation means 121 for calculating the beat frequency from the rotation speed of the three-phase motor 1 determined by the rotation speed calculation means IZG, and a beat frequency calculation means 121 for calculating the beat frequency from the rotation speed of the three-phase motor 1 determined by the rotation speed calculation means IZG; Each time the power spectrum ratio calculation means 12J, the graphic display 19, and the power spectrum ratio calculation means 12J, which calculates the ratio between the beat frequency component and the power supply frequency component of the power spectrum, output the calculation results, the calculation results are sequentially displayed. A second data collection means 12F for storing data in the memory 16 of the second memory 16, and a data processing means Om for graphically displaying a plurality of calculation results stored in the second memory 16 on a graphic display 19. As described above, the motor diagnostic device of the first invention is configured to determine the phase unbalance rate and amplitude unbalance rate that change depending on the degree of abnormality in the stator coil of a three-phase motor, and Data on the phase unbalance rate and amplitude unbalance rate obtained for each period is sequentially stored in the second memory, and the data on the phase unbalance rate and amplitude unbalance rate stored in the second memory is processed and graphically displayed. Because it is displayed, it is possible to quantitatively display the progress of abnormalities in the stator coil of a three-phase motor, and it is possible to diagnose stake coils accurately without individual differences, and to manage trends. . What's more, instead of manual recording, the graphic display is automatically performed by storing data in memory, reading data from memory, and processing the data, so graphs can be created in a short time without mistakes, making trend management extremely easy. It can be carried out.

Further, the motor diagnostic device of the second invention is configured to determine the ratio of the beat frequency component of the power spectrum of the primary current of the three-phase motor to the power frequency component, which changes depending on the degree of abnormality in the rotor coil, etc. of the three-phase motor. At the same time, the ratios obtained at each predetermined period are sequentially stored in memory, and the ratio data stored in memory is processed and displayed graphically, making it easy to see the progress of abnormalities in the rotor coil of a three-phase motor. It can be displayed quantitatively, the rotor coil can be diagnosed accurately without individual differences, and trends can be managed. What's more, instead of manual recording, the graphic display is automatically performed by storing data in memory, reading data from memory, and processing the data, so graphs can be created in a short time without mistakes, making trend management extremely easy. It can be carried out.

Embodiment An embodiment of the present invention will be described with reference to FIGS. 2 to 9. As shown in Fig. 2, this electric motor diagnostic device has the following features:
1 of the 1st phase and 3rd phase of the 3-phase induction motor 1 to be diagnosed
The next current is detected by current transformers (current detectors) 2 and 3 and applied to the first input terminal 4 and second input terminal 5, and the rotation speed of the three-phase induction motor l is detected by the pulse generator (rotation detector) 6. in addition to the third input terminal 7, each input terminal 4
The signal added to ゜5.7 is sent to A/D converter 8, 9゜10
The configuration is such that A/D conversion is performed for each.

The A/D conversion process of this A/D converter 8.9.10 is as follows:
The output frequency of the sampling pulse generator 11 is determined by the sampling pulse frequency setting signal from the central processing unit 12 during stator coil diagnosis (waveform analysis). is set to, for example, 256 times the power supply frequency, and during rotor coil diagnosis (frequency analysis), it is set to, for example, 16 times the power supply frequency.

The central processing unit 12 collects the waveform data output from the A/D converters 8, 9, and 10 and stores them in the memory 13.
By performing various calculations based on the waveform data stored in the memory 13, diagnosis of the stator coil of a three-phase induction motor (layer short circuit) is performed.

Obtain data for diagnosing low coils (detecting disconnections and loose wires) and diagnosing low coils (detecting layer shorts and disconnections).
This data is displayed on display devices 14 and 15.

1G is a memory backed up by a battery or the like, 17 is a transmission circuit, 18 is a data processing device, and I9 is a graphic display device, the operations of which will be described later.

Note that the memory 13 not only stores the collected waveform data but also stores programs for diagnosing the stator coils and rotor coils.

Hereinafter, the operation of this motor diagnostic device will be explained in detail with reference to FIGS. 3 to 9.

As shown in FIG. 3, the central processing unit I2 first performs a diagnostic operation for the stator coil (step U), then performs a diagnostic operation for the rotor coil (step U2), and finally displays the diagnostic results for the stator coil and rotor coil. (Step U3) In diagnosing the six stator coils, the central processing unit 12 first sets the sampling frequency to one for stator coil diagnosis (for example, a frequency 256 times the power supply frequency), as shown in FIG. A sampling pulse frequency setting signal is given to the sampling pulse generator 11 (step registration). As a result, the sampling pulse generator 1'1 generates a sampling pulse with a frequency 256 times the power supply frequency, and the A/D converter 8.9 generates a sampling pulse in FIGS. 5(A) and 5(B) based on this sampling pulse. ),
Among the primary currents of the first phase, second phase, and third phase of the three-phase induction motor l shown in (C), one light current of the first phase and the third phase is A/D converted and waveform data D , , D3 columns will be output.

Next, the central processing unit I2 receives the first phase and third phase waveform data D, , D from the A/D converter 8.9 as many times as necessary for diagnosing the stator coil (several cycles of the power supply frequency).
3 is collected and stored in the memory 13 (step v2), and the timing waveform data D, , D stored in the memory 13 is collected.
By calculating the following equation every 3, the three-phase induction motor l
The waveform data D2 corresponding to the second phase primary current is obtained and stored in the memory 13.

D2=-(D, +D3) ・・・・・・(1)
The calculation of the above equation (11) is normally held because the zero-sequence current is extremely small and there is a relationship of D1+D2+D3#O.The waveform data D2 of the second phase primary current is , it is also possible to obtain it by providing one set of current transformers and an A/D converter without performing the calculation of equation (1).

Next, the central processing unit 112 stores the waveform data D1 . of each phase stored in the memory 13 . D2. 1st, 2nd from D8. Zero cross phase g1 when the current value of each third phase changes from a negative value to a positive value. /2. x3 (Fig. 5), and waveform data D, , D2 . Select the amplitudes (peak values) AI, , AI2'+ AI3 from D3, respectively. -e3 to phase difference PI2 of each phase. P
23. P3+ is determined by the following formula (step 5).

Next, the first. Second. Phase difference of each third phase P12゜PP
The largest one PMA X and the smallest PMIN
and further select the amplitude A11 . Similarly for AI2゜AI3, the maximum AI, 4Ax and the minimum AI
Select MIN (step V6). Next, calculate the phase unbalance rate UBP by performing the calculation according to the following equation.
and the amplitude unbalance rate UBA (step 7).

(Left below) PMAX PMTN AI, +AI2 +AI3 Next, when diagnosing the rotor coil, the central processing unit 1
2, as shown in FIG. 6, first, a sampling pulse frequency setting signal is given to the sampling pulse generator 11 to set the sampling frequency for rotor coil diagnosis (for example, a frequency 16 times the power supply frequency) (step W,
). As a result, the sampling pulse generator 11 generates a sampling pulse with a frequency 16 times the power supply frequency,
A/D converter8. IO converts the primary current of the first phase of the three-phase motor 1 into A/D based on this sampling pulse and outputs a sequence of waveform data D1', and also converts the output of the pulse generator 6 into an A/D converter. The data will be converted and output as data D4.

Next, the central processing unit 12 collects waveform data D1' and data D4 from the A/D converters 8 and 10 as many times as necessary for diagnosing the rotor coil (several tens of cycles of the power supply frequency) and stores them in the memory 13. (Step W2).

Next, the power spectrum of the primary current of the first phase is obtained by reading out the waveform data D1' from the memory 13 and performing frequency analysis (Fourier transform is performed with several tens of cycles of the power supply frequency as one cycle). W
3).

Next, data D4 is read from the memory 13, the number of sampling data within a period is counted from the timing when data D4 becomes "1" until the timing when data D4 becomes "1" next, and this number of sampling data and the sampling frequency are calculated. The rotation speed N (rpm) of the three-phase induction motor 1 is determined based on the number of pulses output from the pulse generator 6 per one rotation of the three-phase induction motor 1, and further, this rotation speed N and the synchronous rotation speed Ns (rpm) are calculated. The calculation shown in the following equation is performed to calculate the total S (step W4).

S Next, the beat frequency fs is determined by calculating the following formula based on the suberi S and the power supply frequency f0 (step W
5).

fs"fgX (1-2XS) ... (6
Next, the power spectrum value P(fs) at the beat frequency fs and the power spectrum value P(fo) at the power supply frequency "." are selected from the Fourier transform results stored in the memory 13, and the power spectrum values P(fs),
, -P (fo) is calculated by the following equation (step W6).

P(fo) Next, in displaying the diagnosis results, the central processing unit 12 first digitally displays the data of the phase unbalance rate UBP and the amplitude unbalance rate UBA obtained in the stator coil diagnosis process on the display 14. At the same time, data is plotted on the display 15 with the phase unbalance rate UBP on the horizontal axis and the amplitude unbalance rate UBA on the vertical axis. Next, the beat frequency fs and the power spectrum ratio obtained in the rotor coil diagnosis process are digitally displayed on the display 14, and the power spectrum is graphically displayed on the graphic display 15 with the power frequency component set as 100%.

Here, the above-mentioned phase unbalance rate UBP and amplitude unbalance rate UBA and stator coil layer'? −G, disconnection,
Relationship with looseness and beat frequency fs'
power spectrum value P(fs) and power supply frequency r. The relationship between the power spectrum value P(fo) and the rotor coil chassis 1ff-t and wire breakage will be explained.

First, the former will be explained. All of the tested motors were three-phase induction motors with a rated output of 3 KW, and some had one pole of the stator coil short-circuited between the eyebrows or the windings were loosened. For such a large number of three-phase induction motors, the phase unbalance rate UBP and amplitude unbalance U are determined respectively.
I asked for BA.

Figure 7 plots the detection results for each tested motor, with the horizontal axis representing the phase unbalance rate UBP and the vertical axis representing the amplitude unbalance rate UBA. The white triangles indicate those with short circuits, and the white triangles indicate those with loose connections.

In addition, the Not motor is used as a representative of the normal motor group.
In addition, we selected the NO2 motor as a representative of the motor group with interlayer short circuit, and calculated the phase difference PIZ, P23 for each motor.
．． P31. Amplitude AI,, A12°Al1. Table 1 shows the phase unbalance rate UBP and the amplitude unbalance rate UBA.

(Leaving space below) Table 1 As is clear from Figure 7, the region where both the phase unbalance rate UBP and the amplitude unbalance rate UBA are small, specifically, the area where UBP ≦ 20% and UBA ≦ 20%. , can be considered as a normal region where no glabella short circuit or looseness occurs in the three-phase induction motor, and 20% < UB
The area where P < 40% or 20% < UBA < 40% is an abnormal area where the stator coil is loosened or a short circuit between the eyebrows occurs in a minute area, and UBA ≥ 40% or UBP ≥ 40%. The above region can be regarded as an abnormal region where a glabellar short circuit has occurred in the stator coil.

Therefore, if we detect the phase unbalance rate UBP and amplitude unbalance rate UBA for the three-phase induction motor actually used, and see where this three-phase induction motor is located in Fig. 7, we can find that the stator coil It is possible to quantitatively determine the presence or absence of short-circuited or loose eyebrows. Furthermore, as the pro-node position moves from left to right or from bottom to top in FIG. 7, that is, as the phase unbalance rate UBP or amplitude unbalance rate UBA increases, the stator coil abnormality progresses. It is possible to make judgments and monitor changes over time.

As mentioned above, the phase unbalance rate UBP and the amplitude unbalance rate UBP can be quantified, so experiments were conducted.

A normal region as shown in FIG. 7 obtained from actual results is determined in advance as judgment 71, and the phase unbalance rate UBP and amplitude unbalance rate UBA of the three-phase induction motor to be judged are determined.
The three-phase induction It is possible to accurately judge whether the electric motor is normal or abnormal.

Next, the power spectrum value P(fs) at the beat frequency f and the power supply frequency f. The relationship between the power spectrum value P(fo) and the layer short disconnection of the rotor coil will be explained. The use of the test motor is as follows. - Rated output 3KW Rated voltage: 400V Rated current: 12A Number of poles: 6 Rated rotation speed: 1144rpm Synchronous rotation speed: 1200rpm Power frequency: 60Hz Figure 8 (A) shows the normal rotation of the three-phase induction motor. It is a primary current waveform diagram of the first phase, where the vertical axis shows amplitude and the horizontal axis shows time.

FIG. 8(B) shows the power spectrum, where the vertical axis shows the percentage of the effective value and the horizontal axis shows the frequency.

FIG. 9(A) is a first phase primary current waveform diagram when the rotor winding is unbalanced, and FIG. 9(B) is its power spectrum.

Since the detected rotational speed during normal operation was 1144 rpm, the slip Sl was 0.0467 as shown in equation (8).

Then, the beat frequency fsl is 54°4 Hz as shown in equation (9).

rs1=sox (12X0.0467)=54.4H
z ... (9) As is clear from Figure 8 (A), in this case, no beat waveform appears in the primary current waveform, and from Figure 8 (B), 54.4 Hz.
It can be seen that the level of is O.

On the other hand, since the rotation speed detected at the time of abnormality was 1110 rpm, the slip S2 becomes 0.075 as shown in the αωth equation. Then, the beat frequency fs2 becomes 51 Hz as shown in equation (11).

f S 2 = 60 X (12X O,075) =
5111z... (11) As is clear from Figure 9 (A), the primary current wave,
A power spectrum of about 9% is seen at 51 Hz, and from this it is known that D=9%, and an abnormality in rotation can be detected.

In this way, the beat frequency can be accurately known, and abnormalities in the rotation of the motor can be detected from the ratio with the power spectrum at the power supply frequency. Therefore, if a criterion value obtained through experimentation or actual results is determined, a quantitative determination of normality or abnormality can be made by directly comparing the detection result with the criterion value. As a result, it is possible to diagnose the electric motor regardless of individual differences, and it is possible to prevent serious failures of the electric motor.

Here, the reason why the waveform analysis frequency is set to 256 times the power supply frequency and the frequency analysis frequency is set to 16 times the power supply frequency will be explained.

First of all, the reason why the waveform analysis frequency is set to 256 times the power supply frequency is to increase the measurement precision of the phase unbalance rate UBP and amplitude unbalance rate UBA by keeping the waveform analysis accuracy below 2 degrees and to distinguish between normal and abnormal areas. For example, it is 256 times larger than the critical value. Increasing the frequency further increases accuracy.

On the other hand, the reason why the frequency analysis frequency is set to 16 times the power supply frequency is as follows. In other words, a small amount of data (several tens of cycles worth) is required to perform frequency analysis, but if these tens of cycles worth of data were sampled and collected at the waveform analysis frequency, the capacity of the memory 13 would be enormous. In order to reduce the capacity of this memory 13, the sampling frequency is lower than the waveform analysis frequency.
Sampling may be performed at a frequency higher than twice the frequency. However, in this case, the lower limit of the sampling frequency is about 8 times the power supply frequency. If the frequency is lower than this, an aliasing error will appear, and the frequency analysis accuracy will decrease.

Here, the aforementioned memory 16. The operation of the transmission circuit 17, the data processing device 18, and the graphic display device 19 will be explained.

This motor diagnostic device sequentially performs a stator coil diagnostic operation and a rotor coil diagnostic operation on a plurality of three-phase induction motors 1, and data P1 obtained by each diagnostic operation.
□, P23. P3. ．． UBP.

AI,,A12. AI3. UBA, N8. N.S.

f3. D and the number No. of the three-phase induction motor 1 are sequentially stored in the memory 16 in the format shown in FIG. 10, and each data stored in the memory 16 is stored in the format shown in FIG. Transmission circuit 17
The data will be sent to the external data processing device 18 through.

The motor diagnostic device performs diagnostic operations on a plurality of three-phase induction motors at predetermined intervals, and sends the obtained data to the data processing device 18.

The data processing device 18 stores data sent through the transmission circuit 17 at predetermined intervals in a memory (not shown), classifies the data stored in the memory by number NO of the three-phase induction motor l, and stores the classified data. Specifically, data on the phase unbalance rate and amplitude unbalance rate obtained by the stator coil diagnostic operation is processed and displayed on a graphic display device, with the phase unbalance rate on the horizontal axis and the amplitude unbalance rate on the vertical axis. You can plot the data for each predetermined period sequentially on the axis, or
Alternatively, data on phase unbalance rate and amplitude unbalance rate can be displayed with time as the horizontal axis. Further, the beat frequency component and power frequency component Q ratio of the power spectrum of the frequency analysis result of the primary current of the three-phase induction motor obtained by the rotor coil diagnostic operation are displayed with time as the horizontal axis.

In this way, the data of the phase unbalance rate and amplitude unbalance rate obtained at each predetermined period are stored in the memory, and the data stored in the memory is processed and displayed graphically, so that the progress of abnormalities in the stator coil can be easily monitored. I understand, and also,
The ratio of the beat frequency component of the power spectrum and the power supply frequency component obtained at each predetermined period is stored in memory, and the data stored in memory is processed and displayed graphically, allowing the progress status of abnormalities such as rotor coils to be understood. It becomes easy to manage trends in three-phase induction motors.

Note that the data 12 of the three-phase induction electric motor AT for each predetermined period may be processed and displayed graphically on the display 15.

Effects of the Invention The motor diagnostic device of the first invention calculates the phase unbalance rate and the amplitude unbalance rate that change depending on the degree of abnormality of the three-phase motor stator coil, and also calculates the phase unbalance rate calculated at predetermined intervals. The data on the phase unbalance rate and amplitude unbalance rate are sequentially stored in the second memory, and the data on the phase unbalance rate and amplitude unbalance rate stored in the second memory is processed and displayed graphically. The progress of abnormality in the stator coil of the electric motor can be displayed quantitatively, the stator coil can be diagnosed accurately without individual differences, and trends can be managed. What's more, instead of manual recording, graphic display is performed automatically by storing data in memory, reading data from memory, and processing the data, so graphs can be created in a short time without mistakes, and trend management is extremely easy. The motor diagnostic device according to the second aspect of the invention can detect the ratio of the beat frequency component of the power spectrum of the primary current of the three-phase motor to the power frequency component, which varies depending on the degree of abnormality in the rotor coil, etc. of the three-phase motor. At the same time, the ratios obtained at predetermined intervals are sequentially stored in the memory, and the data of the ratios stored in the memory is processed and displayed graphically, so that the progress of abnormalities such as the rotor coil of a three-phase motor can be easily monitored. can be displayed quantitatively, the rotor coil can be diagnosed accurately without individual differences, and trends can be managed. What's more, instead of manually recording data, it records data in memory, reads data from memory, and processes the data to automatically display graphics, allowing graphs to be created in a short time without mistakes, and greatly simplifying direction management. It can be easily installed.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention, FIG. 2 is a block diagram of an embodiment of the invention, FIG. 3 is a flowchart showing the main program of the central processing unit, and FIG. 4 is the same as that shown in FIG. Detailed flowchart of stator coil diagnosis, Figure 5 is a waveform diagram of the primary current of a three-phase induction motor,
Figure 6 is a detailed flowchart of the rotor coil diagnosis in Figure 3, Figure 7 is an explanatory diagram of the relationship between the phase unbalance rate and amplitude unbalance rate and whether the stator coil is normal or abnormal.
9 and 9 are explanatory diagrams of the relationship between frequency analysis results and whether the rotor coil is normal or abnormal, and FIGS. 10 and 11 are explanatory diagrams of data formats. 1... Three-phase induction motor, 2, 3... Current transformer (current detector), 6... Pulse generator (rotation detector),
8.9... A/D converter, 11... Sampling pulse generator, 12... Central processing unit, 12A... Frequency setting means, 12B... First data collection means, 1
2C: Phase difference calculation means, 12D: Amplitude calculation means, 12E: Phase unbalance rate calculation means, 12F: Amplitude imbalance rate calculation means, 12G: Rotation speed calculation means, 1
2H...Second data collection means, 12I...Frequency analysis means, 12J...Beat frequency calculation means, 12K
...spectral ratio calculation means, 13...memory, 16
...Memory, 17...Transmission circuit, 18...Data processing device, 19...Graphic display device'F), 3 Figure A11 Figure 5 Figure 6rjA Figure 7 Figure 8 Figure 9 Figure 10

Claims (2)

[Claims] (1) A current detector that detects the primary current of a three-phase motor;
an A/D converter that A/D converts the output of the current detector; a first data collection means that collects waveform data output from the A/D converter and stores it in a first memory; a phase difference calculation means for calculating the phase difference between each phase current from the waveform data stored in the first memory; an amplitude calculation means for calculating the amplitude of each phase current from the waveform data stored in the first memory; a phase unbalance rate calculating means for calculating a phase unbalance rate from the difference between the maximum and minimum phase difference of each phase current calculated by the phase difference calculating means; An amplitude unbalance rate calculating means for calculating an amplitude unbalance rate from the difference between the minimum values; A motor diagnostic device comprising: second data collection means stored in a second memory; and data processing means for data processing a plurality of calculation results stored in the second memory and displaying the data in graphics on the graphic display. . (2) a current detector that detects the primary current of the three-phase motor;
a rotation detector for detecting the rotation of the three-phase motor; an A/D converter for A/D converting the output of the current detector; and a rotation for determining the rotation speed of the three-phase motor from the output of the rotation detector. a numerical calculation means; a first data collection means for collecting waveform data output from the A/D converter and storing it in a first memory; a frequency analysis means for calculating a power spectrum of each frequency by performing frequency analysis; a beat frequency calculation means for calculating a beat frequency from the rotation speed of the three-phase motor calculated by the rotation speed calculation means; power spectrum ratio calculation means for calculating the ratio between the beat frequency component and the power supply frequency component of the power spectrum obtained by the power spectrum; a second data collection means for storing in memory;
A motor diagnostic device comprising: data processing means for data processing a plurality of calculation results stored in the second memory and displaying the data in graphics on the graphic display.