JP5584036B2 - Deterioration diagnosis device - Google Patents

Description

  The present invention relates to a deterioration diagnosis apparatus that attaches an electric motor having a rotor and a stator to a test jig and diagnoses a winding insulation state of the attached electric motor.

  Conventionally, in an electric motor used for an industrial machine in a chemical plant factory, once an accident due to insulation deterioration occurs, a huge social loss such as plant shutdown occurs in addition to the time and cost required to restore the equipment. There are things to do. For this reason, various insulation diagnosis techniques for stator windings have been developed for high-voltage motors that drive large-capacity turbo pumps.

  Patent Document 1 discloses a diagnostic method in which an insulating coil is vibrated by hammering, the natural frequency is measured, and winding looseness due to insulation deterioration is determined based on a vibration waveform that changes with time. Yes. Patent Document 2 discloses a method of directly or indirectly exciting a winding with a large current surge and detecting looseness of the winding from its vibration peak value, frequency, waveform attenuation factor, and the like. . Further, Patent Document 3 relates to an insulation diagnostic device for electric power equipment such as a gas insulated switchgear, a gas circuit breaker, a cubicle, etc., and a partial discharge generated as a precursor phenomenon of insulation deterioration of the electrical equipment is generated inside or outside the electrical equipment. A technique for detecting with an antenna provided is disclosed.

  Thus, in high voltage motors, visual inspection methods such as fouling, looseness, and discoloration, electrical diagnostic methods such as insulation resistance, PI value, tan δ, AC voltage / current characteristics, partial discharge test, shock wave comparison test, etc. A method for comprehensive judgment by combining the inspection of the sound and the sounding diagnosis as a mechanical diagnosis method has been established, and a temporary result has been obtained.

  On the other hand, the insulation diagnosis technology for low-voltage motors has not progressed for the following reasons. The first reason is that the diagnosis based on the discharge phenomenon that is effective in a high-voltage motor is said to have a voltage at which corona discharge starts is 3000 V, which exceeds the withstand voltage of a low-voltage motor, and is not suitable for a low-voltage motor. is there. The second reason is that the bearing part is likely to break down earlier than the low-voltage motor, and the low-voltage motor has a low renewal cost, so the low-voltage motor itself is often replaced, and insulation diagnosis data is difficult to accumulate. there were.

Japanese Patent Publication No. 01-26500 Japanese Patent Laid-Open No. 11-086689 JP 09-229992 A

  Here, the canned motor pump using the low-voltage electric motor covers the inside of the stator of the electric motor that drives the centrifugal pump with a can, supports the rotor inside the can, and fills the liquid to be handled so that the rotating part of the canned motor pump Is in the handling liquid. In the canned motor pump, since the impeller and shaft of the rotor and centrifugal pump are in the liquid to be handled, sealing of the rotating part is unnecessary, and the bearing has a simple structure like a sliding bearing.

  Since the stator of the canned motor pump is sealed by the can, the motor outer cylinder, and the end plate, the inspection and replacement of the stator windings involve removal of the handling liquid and disassembly of the sealed stator. Since these operations are not limited to simply replacing the low-voltage motor, but are related to the plant, it is necessary to perform an appropriate insulation diagnosis to determine the life of the winding and to perform the timing at the time of inspection of the plant.

  Therefore, the present invention relates to a deterioration diagnosis device for winding insulation, and particularly to provide a deterioration diagnosis device capable of grasping a deterioration state of a low voltage motor such as a canned motor pump.

  In order to achieve the above object, a deterioration diagnosis apparatus according to the present invention is a deterioration diagnosis apparatus that attaches an electric motor having a rotor and a stator to a test jig and diagnoses the winding insulation state of the attached electric motor. The test jig includes an electric motor fixing jig for fixing the electric motor, a shaft fixing jig for fixing an arm-equipped sleeve having an arm provided on a sleeve fitted into the shaft of the electric motor, an electric motor fixing jig and a shaft fixing jig. And a power supply means for exciting the motor by supplying an AC voltage to the motor, and the deterioration diagnosis device is wound around the stator. First vibration measurement means for measuring the vibration value of the motor fixing jig including the vibration value of the winding, and second vibration measurement for measuring the vibration value of the shaft fixing jig connected to the shaft And a difference calculation means for calculating a difference between the vibration value of the motor fixing jig and the vibration value of the shaft fixing jig, and the winding insulation state of the motor based on the vibration value calculated from the difference calculation means It is characterized by diagnosing.

  In other words, the vibration component measured by the first vibration measuring unit includes the vibration component of the rotor and the vibration component of the stator (winding), and the vibration component measured by the second vibration measuring unit is mainly the rotor component. Contains vibration components. Assuming that the vibration components of the rotor itself and the stator itself do not change, the difference calculation means can calculate the vibration component of the winding.

  In the deterioration diagnosis apparatus according to another preferred invention, the shaft fixing jig is a shaft fixing jig based on the mass of the electric motor fixing jig, the mass of the shaft fixing jig, and the mass of the rotor having the shaft measured in advance. And adjusting means for adjusting the mass of the shaft fixing jig so that the mass of the rotor becomes equal to the mass of the rotor having the shaft.

In general, the natural frequency f ₀ (Hz) is obtained by a spring constant k (N / m) and a mass M (kg) f ₀ = 1 / 2π · √ (k / M). It is important to preset the frequency of each component so as not to overlap the vibration frequency.

In the deterioration diagnosis apparatus according to another preferred invention, the power supply means supplies a preset AC voltage to the winding of the motor, and the n-order frequency (n is a natural number) of the AC voltage applied to the winding. The deterioration state of the motor is diagnosed on the basis of the vibration value excited in step (1). Since the frequency of the winding accompanying the decrease in the varnish fixing force is empirically known, it is needless to say that excitation by the n-th order frequency of the AC voltage close to that frequency is important.

  By using the deterioration diagnosis device according to the present invention, for example, vibration at the initial delivery is measured without disassembling the motor, and the change over time can be read by acquiring the data during periodic inspection. Can do. If the data tends to increase gradually, it can be considered that the adhesion of the varnish fixing the coil has decreased, and it can be determined that the insulation state of the motor has deteriorated. From this, by collecting data regularly, it is possible not only to grasp the soundness of the motor and make it useful for preventive maintenance, but also to enable planned maintenance and reduce the impact on the plant. effective.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a configuration diagram showing a configuration of a deterioration diagnosis apparatus according to an embodiment of the present invention, in which an electric motor having a rotor and a stator is attached to a test jig and a winding insulation state of the attached electric motor is diagnosed. is there. It is a side view of the shaft fixing tool attached to the electric motor of FIG. 1 is a structural diagram showing a structure of a canned motor pump which is a reference for understanding the present invention. It is a vibration model figure which shows the vibration model of the electric motor attached to the test jig | tool of FIG. It is the characteristic view measured with the deterioration diagnostic apparatus of FIG. It is a characteristic view which shows the relationship between the vibration value measured with the deterioration diagnostic apparatus of FIG. 1, and the magnification of a rated current. It is a flowchart figure which shows the flow of a process of the degradation diagnostic apparatus in this embodiment.

  Hereinafter, the best mode for carrying out the present invention (hereinafter referred to as an embodiment) will be described with reference to the drawings.

  FIG. 1 shows a configuration of a test jig for fixing the motor 14 and a deterioration diagnosis device 30 for diagnosing the winding insulation state of the motor 14. The test jig 60 includes a vibration transmission preventing base 51 that fixes the electric motor 14 having the rotor 22 and the stator 15, and a vibration transmission preventing base 52 that fixes the shaft fixture 61 connected to the shaft 24. . Further, the shaft fixture 61 has a torque meter built-in arm 62 and can measure the rotational torque force of the electric motor. The deterioration diagnosis device 30 measures the vibrations of the control device 2 that controls the power, the power source 4 that supplies power to the electric motor 14 according to the output command of the control device 2, the sensor 5a that measures the vibration of the electric motor 14, and the shaft fixture 61. The vibration sensor amplifier 6 connected to the sensor 5b, the FFT analyzer 7 for analyzing the signal from the vibration meter amplifier 6, and the control device 2 analyze the analysis result from the FFT analyzer 7 and the rotational torque from the torque meter built-in arm 62. It has a display 8a that obtains force and diagnoses the deterioration state and displays information from the control device 2, and an input device 8b that can input various information.

  Here, the structure of the canned motor pump 10 used as a reference in understanding the present invention will be described with reference to FIG. The canned motor pump 10 includes a pump unit 12 and an electric motor 14 that are integrally formed. The electric motor 14 includes a stand 42 and a terminal unit 11 that inputs a three-phase alternating current. The pump section 12 includes an impeller 16 that gives a speed to a handling fluid, and a casing 18 that houses the impeller 16. The electric motor 14 includes a cylindrical stator 15 and a rotor 22 disposed inside the stator 15. The rotor 22 is fixed to a shaft 24. The shaft 24 extends to the pump unit 12, and the impeller 16 is fixed thereto. The can 26 is disposed so as to partition between the stator 15 and the rotor 22, and the outer side of the stator 15 is covered with an electric motor outer cylinder 28, and both ends of the can 26 and the electric motor outer cylinder 28 are annular rings. It is sealed with end plates 31 and 32.

  The end plate 31 on the pump side is fixed to a connection plate 34 fixed to the casing 18. A bearing holder 36 is fixed to the opposite end plate 32, and a space inside the can 26 in which the rotor 22 is disposed is sealed by the can 26, the two end plates 31 and 32, and the bearing holder 36. And communicated with the pump unit 12. The shaft 24 is supported by bearings 38 and 40 which are sliding bearings fixed to the connection plate 34 and the bearing holder 36, respectively, and the handling fluid exhibits a lubricating effect. In other words, when vibration is measured by attaching to a test jig in the absence of a handling fluid, it is necessary to deal with rattling caused by a gap between the shaft 24 and the bearings 38 and 40.

  Therefore, in the test jig according to the present embodiment, rattling due to the gap between the shaft and the bearing is reduced by using the shaft fixture 61 as shown in FIG. In the canned motor pump 10, the pump portion 12 of FIG. 3 is removed, and a sleeve 63 having a torque meter built-in arm 62 is fitted to the shaft 24 instead of the impeller 16. The torque meter built-in arm 62 fitted into the shaft is fixed to the stand 66 with an arm fixing bolt. The stand 66 to which the torque meter built-in arm 62 is fixed has a hole for fixing the arm fixing bolt, a sensor 5b for measuring vibration, and a plurality of weights for adjusting the mass of the shaft fixing tool. doing.

  In this embodiment, in order to concentrate the vibration direction in the vertical direction, a hole for the arm fixing bolt 65 of the stand 66 is provided in order to horizontally arrange the torque meter built-in arm. When AC power is supplied to the motor, the arm with a built-in torque meter presses the stand 66 in the gravitational direction due to the rotational torque, and the shaft is pushed up by the bearing by the vertical reaction force received from the stand 66, and the clearance between the shaft and the bearing is reduced. Shaking will be reduced. Further, by adjusting the mass of the shaft fixture to be equal to the mass of the rotor or the like, the rotor and the shaft fixture are balanced with the pushed-up portion as a fulcrum, and the vibration generated by the rotor is detected by the sensor 5b of the shaft fixture. It becomes possible to measure efficiently.

  Next, the vibration model of the electric motor attached to the test jig will be outlined. The characteristic feature of the present invention is to detect the vibration of the winding due to a decrease in the varnish fixing force without removing the rotor in order to simplify the measurement work. In general, in order to apply a large current exceeding the rated current to the stator primary winding with the rotor inserted, it is necessary to forcibly increase the load factor. Dedicated equipment that can be used is required. Therefore, in this embodiment, the rotation of the rotor is stopped by the shaft fixing jig, and the vibration generated by the rotation of the rotor and the vibration generated by the electromagnetic force acting between the rotor and the stator are reduced. The mass, the spring constant, and the damping coefficient were set so as to provide a test jig that emphasizes the vibration caused by the looseness of the coil itself while separating the excitation force generated by the vibration by the vibration transmission prevention stand described later.

  An outline of the vibration model of FIG. 4 will be described. The vibration model includes (A) a stator model 72, (B) a rotor model 73, (C) a shaft fixing model 74, and a seesaw model 71 that mechanically connects the rotor model 73 and the shaft fixing model 74. This is a vibration model of a multi-degree-of-freedom system. This model shows a configuration for separately measuring the vibration of the stator and the rotor by the sensor 5a for measuring the vibration of the motor outer cylinder and the sensor 5b for measuring the vibration of the shaft fixture. In addition, in order to make a vibration model that efficiently extracts the vibration of the stator including the vibration of the winding, the vibration model is simplified by concentrating the vibration direction in the vertical direction.

In the stator model 72, a stator having windings has a mass m ₁ (kg), a spring constant k ₁ (N / m), a damping coefficient c ₁ (N · s / m) proportional to speed, and a ground displacement x _0. , The displacement of the mass m ₁ is expressed as x ₁ . The rotor model 73 is connected to the stator model 72, it expresses the rotor having a shaft mass m _2, the spring constant k _2, the attenuation coefficient c _2, the displacement of the mass m ₂ as x _2.

The shaft fixing model 74 is expressed as mass m ₃ , spring constant k ₃ , damping coefficient c ₃ , ground displacement x ₀ , and mass m ₃ displacement x ₃ . The shaft fixing model 74 is connected to the rotor model 73 via a seesaw model 71 that models a bearing, a shaft, and a torque meter built-in arm. The shaft fixing model 74 has substantially the same mass m ₃ as the rotor model 73. By having it, it is comprised so that the rotor model 73 may be balanced.

First, the equation of motion of the stator model 72 will be described. The stator model 72 has a ground-side spring constant k ₁ and a damping coefficient c _1, and a mass m ₂ -side spring constant k ₂ and a damping coefficient with a mass m ₁ in between, as shown in the range indicated by symbol A in FIG. It can be expressed as Equation 1 by c ₂ . Here, the spring constant shows a characteristic corresponding to the displacement, damping factor will indicate characteristics according to the speed, the section left side of the ground side as shown in Equation 1, the term of the right side mass m ₂ side It becomes the formula which has.

Next, assuming that the mass m ₁ is the ground, the rotor model 73 as in the range indicated by the symbol B and the shaft fixing model 74 as the range indicated by the symbol C are the mass m2 and the mass m3. Can be expressed similarly. Assuming that Pcosωt is applied to the rotor model 73 as the amplitude P (N) of the excitation force generated by supplying AC power and the angular frequency (circular frequency: rad / s), Equation 2 shows Such a left side is a term on the rotor side, and a right side is a term on the shaft fixing side, which are respectively equal to P cos ωt.

Here, when the formula 2 is transformed by paying attention to the rotor model 73 that generates the excitation force, the formula 3 is obtained and becomes the same term as the right side of the formula 1.

When the obtained Expression 3 is substituted into Expression 1, an expression relating to the stator model and the rotor model as shown in Expression 4 is obtained.

Here, since the excitation force applied to the rotor model 73 and the shaft fixing model 74 is seesaw-connected, it is assumed that the value of the antiphase is as shown in Equation 5.

When Expression 5 is substituted into Expression 4 and the term of the stator model 72 and the term of the rotor model 73 are moved to the left side, Expression 6 in which the excitation force of the rotor model 73, the stator model, and the shaft fixing model 74 are related is obtained. .

When formula 6 is modified and the terms of the stator model and shaft fixing model 74 are summarized on the left side, a value obtained by subtracting the acceleration of the shaft fixture from the acceleration of the stator is a predetermined value related to the excitation force Pcosωt as shown in formula 7. You can see that

  Next, a test flow of the deterioration diagnosis apparatus in the present embodiment will be described with reference to the flowchart of FIG. 7 and FIG. In the test method, an AC voltage is applied so that a current n times the rated current flows in a state where the rotor 22 of FIG. 1 is assembled to the stator 15, and the vibration at that time is measured and diagnosed.

  First, in step S10, time-dependent information such as stator mass and rotor mass at the time of manufacture, vibration characteristics, usage time, and maintenance records based on the serial number of the motor 14 is obtained from the deterioration information database 3 (hereinafter abbreviated as DB). Information is acquired and it moves to step S12.

  Next, in step S12, the electric motor is attached to the test jig 60, and the shaft fixture 61 is attached to the shaft so that the rotor 22 does not rotate. Here, the vibration transmission preventing base 51 that fixes the electric motor (stator side) and the vibration transmission preventing base 52 that supports the shaft fixture 61 are separated so as not to transmit vibration. Further, sensors 5a and 5b (accelerometers) for detecting vibrations are attached to the electric motor 14 and the shaft fixture 61, and the torque meter output from the shaft fixture is connected to the degradation diagnostic device 2 and controlled by the degradation diagnostic device 2. The power source 4 is connected to the electric motor 14.

  Next, in step S14, a current to be applied to the deterioration diagnosis apparatus is set. The setting of the rated current is, for example, 0.5 times (50%) / 1.0 times (100%) / 1.25 times (125%) / 1.5 times (150%) / 1.75 of the rated current. Double (175%) / 2.0 times (200%) / 3.0 times (300%) current is allowed to flow. When the current is applied to the motor 14, in step S16, the signal amplified by the vibration meter amplifier 6 is frequency analyzed by the FFT analyzer 7 and the output of the torque meter is acquired in order to measure the measurement signal. In the analysis result, peaks appear at the resonance frequency (for example, set to 10 Hz) of the vibration transmission preventing base and the nth order of the frequency fHz of the AC voltage. The vibration component of the sensor 5a attached to the electric motor 14 includes the vibration component of the rotor and the vibration component of the stator (winding), and the vibration component of the sensor 5b attached to the shaft fixture 61 is mainly composed of the vibration component of the rotor. It becomes.

  Next, in step S18, the difference value between the sensor 5a and the sensor 5b can be calculated to detect “a vibration component due to a decrease in varnish fixing force”. In step S20, n-fold frequency components including the characteristic 2f component are extracted, and the process proceeds to step S22. In step S22, the result extracted in the deterioration information DB is stored together with the rated current value and the torque value. In step S24, the test is repeated up to 300% of the rating.

  After the series of tests is completed, the stored data is read from the deterioration information DB in step S26. In step S28, if the data value is in an upward trend by performing trend management for comparison with the results measured in the past, the coil vibration may increase due to a decrease in the adhesion of the varnish, resulting in a poor insulation state. Therefore, it is possible to determine whether the motor is in an insulated state.

  FIG. 5 is an example of a characteristic diagram measured by the deterioration diagnosis apparatus 30, where the horizontal axis indicates the frequency and the vertical axis indicates the vibration value. In the figure, a peak is seen at n times the AC voltage frequency of 60 Hz, while a peak is also seen at 10 Hz, which is the resonance frequency of the vibration transmission preventing base. As described above, the two vibration transmission preventing bases not only stop the rotation of the motor but also can efficiently detect the vibration value of the winding by minimizing the influence on the frequency of the winding appearing in 2f. It becomes possible.

  Further, according to the difference between the vibration values measured on the stator side and the shaft side, since a difference appears in addition to 2f, it is not determined only by 2f. For example, the varnish fixing force is based on the difference from 2f to 6f. It is also preferable to determine a decrease in the.

  FIG. 6 is a characteristic diagram in which the vibration value measured by the deterioration diagnosis apparatus and the magnification of the rated current are measured from 50% to 300%. In the figure, the horizontal axis indicates the rated current magnification, and the vertical axis indicates the characteristics depending on the vibration value and the age of the motor.

  From the characteristic diagram, those with a service life of 15 years or less show no change in vibration value even when the magnification of the rated current is changed, indicating that the varnish fixing force is not reduced. As the number of years of use increased to 20 years and 30 years, the change in vibration value increased, so we were able to find some regularity.

  On the other hand, even if the service life is about 20 years, the deteriorated product with reduced varnish adhesion has a larger vibration value than the normal service product, and is proportional to the rated current magnification. Since the vibration value becomes large, it can be seen that it is possible to determine a deteriorated product.

  As described above, by using the deterioration diagnosis apparatus according to the present embodiment, the electromagnetic vibration at the initial stage of delivery is measured, and the change over time can be read by acquiring the data during periodic inspection. Is possible. Moreover, if the data has a tendency to increase gradually, there is an advantage that it can be determined that the fixing force of the varnish fixing the coil is reduced and the insulation state of the motor is deteriorated.

  Therefore, by collecting data regularly, the health of the motor can be grasped and used for preventive maintenance. Furthermore, planned maintenance is possible, and the impact on the plant can be reduced. In addition, by using the deterioration diagnosis apparatus according to the present embodiment, the test can be performed with the rotor inserted without disassembling the electric motor, so that there is an advantage that the number of test steps can be reduced.

  In this embodiment, the motor and the shaft fixing jig are supported by using two vibration transmission preventing bases. However, the vibration transmission preventing base has a function of preventing vibrations from being transmitted in a vertical direction. Needless to say, it is necessary to arrange an elastic body such as a coil spring or rubber, a damper, a damping resin, or the like as a damping material in consideration of the center of gravity of the structure to be supported.

  2 control device, 3 deterioration information database, 4 power supply, 5 sensor, 6 vibrometer amplifier, 7 FFT analyzer, 8a display, 8b input device, 10 canned motor pump, 11 terminal unit, 12 pump unit, 14 motor, 15 stator , 16 impeller, 18 casing, 22 rotor, 24 shaft, 26 can, 28 motor outer cylinder, 30 deterioration diagnosis device, 31, 32 end plate, 34 connection plate, 36 bearing holder, 38, 40 bearing, 42 stand, 51, 52 vibration transmission prevention stand, 60 test jig, 61 shaft fixture, 62 arm with built-in torque meter, 63 sleeve, 65 arm fixing bolt, 66 stand, 71 seesaw model, 72 stator model, 73 rotor model, 74 shaft fixed model.

Claims (3)

In a deterioration diagnosis device that attaches an electric motor having a rotor and a stator to a test jig and diagnoses the winding insulation state of the attached electric motor,
The test jig is
An electric motor fixing jig for fixing the electric motor;
A shaft fixing jig for fixing a sleeve with an arm provided with an arm on a sleeve fitted into the shaft of the electric motor;
A vibration isolation base that supports the motor fixing jig and the shaft fixing jig separately and insulates each other's vibrations;
Power supply means for exciting the motor by supplying an AC voltage to the motor,
The deterioration diagnosis device
First vibration measuring means for measuring a vibration value of a motor fixing jig including a vibration value of a winding wound around a stator;
A second vibration measuring means for measuring a vibration value of a shaft fixing jig connected to the shaft;
Difference calculation means for calculating the difference between the vibration value of the motor fixing jig and the vibration value of the shaft fixing jig, and diagnosing the winding insulation state of the motor based on the vibration value calculated from the difference calculation means A deterioration diagnosis device characterized by that. In the deterioration diagnosis apparatus according to claim 1,
The shaft fixing jig is based on the pre-measured mass of the motor fixing jig, the mass of the shaft fixing jig, and the mass of the rotor having the shaft, so that the mass of the shaft fixing jig becomes equal to the mass of the rotor having the shaft. As described above, a deterioration diagnosis apparatus having adjustment means for adjusting the mass of the shaft fixing jig. In the deterioration diagnostic apparatus according to claim 1 or 2,
The power supply means supplies a preset AC voltage to the winding of the motor,
A deterioration diagnosis apparatus characterized by diagnosing a deterioration state of an electric motor based on a vibration value excited at an n-order frequency (n is a natural number) of an AC voltage applied to a winding .

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