JP2009050078A - Device and method for determining abnormality of machine and equipment - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an abnormality determining device of a machine and equipment, which can highly precisely determine abnormality and with which a result of abnormality determination is difficult to be affected by a change of an operation situation of the other motor sharing a power supply with a subject motor. <P>SOLUTION: The abnormality determining device of machine and equipment is provided with a current detecting means 2 detecting load current supplied to the motor 102, a removal frequency determining means 6 determining a frequency whose voltage component is the largest in voltage components of respective frequencies forming load voltage applied to the motor for supplying load current or a frequency whose voltage component is not less than a first threshold TH1 as a removal frequency, a removing means 7 removing a current component of the removal frequency from load current detected by the current detecting means, a first deciding means 9 deciding whether the current component of not less than a second threshold TH2 is included in load current from which the current component of the removal frequency is removed and an abnormality determining means 10 determining abnormality of machine and equipment when the first deciding means decides that it is included. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to an abnormality determination device for machine equipment driven by an electric motor and an abnormality determination method for machine equipment.

  Examples of mechanical equipment driven by the electric motor include rotating machines such as a blower, a pump, and a belt conveyor driving device. Examples of abnormalities in these mechanical facilities include abnormalities in parts alignment, wrinkles that occur in bearings, and missing parts. Such an abnormality determination of a mechanical facility can be performed by installing a number of sensors in the mechanical facility and directly detecting the abnormality of the mechanical facility.

  The above-described abnormality determination method requires a large number of sensors and signal cables. Therefore, the procurement cost of the sensors, the wiring work cost of the signal cables from the mechanical equipment to the electrical room, and the maintenance costs of the sensors and signal cables are high in practical use. Have the disadvantages. Therefore, Patent Documents 1 and 2 have proposed the following abnormality determination methods.

  The abnormality determination method proposed in Patent Document 1 detects a load current supplied to an electric motor, and the load current is equal to or higher than a preset fixed setting upper limit value or a preset fixed setting lower limit. If the value is less than or equal to the value, it is a method of determining that the mechanical equipment is abnormal.

On the other hand, in the abnormality determination method proposed in Patent Document 2, frequency analysis is performed on the load current supplied to the motor, and the mechanical equipment is based on the current component of each frequency forming the load current obtained by the frequency analysis. This is a method for determining whether or not there is an abnormality.
Japanese Patent Publication No. 6-95059 Japanese Patent Laid-Open No. 11-83686

  However, the abnormality determination method of Patent Document 1 cannot perform abnormality determination with high accuracy. This is because it is difficult for the abnormality determination method of Patent Document 1 to detect an abnormality that has a small effect on the magnitude of the load current. In order to detect such an abnormality by the abnormality determination method of Patent Document 1, it is necessary to make the fixed setting upper limit value and the fixed setting lower limit value close to the load current value when the mechanical equipment is in a normal state. However, if the fixed setting upper limit value and the fixed setting lower limit value are brought close to the load current value when the machine equipment is in a normal state, an error may occur even if the machine equipment is normal due to erroneous detection of current due to noise or the like. This increases the possibility of being judged as abnormal. Therefore, the abnormality determination method disclosed in Patent Document 1 cannot perform abnormality determination with high accuracy.

  Moreover, in the abnormality determination method of patent document 2, there is a possibility that the abnormality determination cannot be performed accurately if the operating conditions of the motor that drives the mechanical equipment that is the target of abnormality determination and other motors that share the power supply change. is there. This is because the harmonic component of the load current obtained by frequency analysis is likely to fluctuate due to changes in the operating conditions of other motors and the like.

  The present invention is capable of performing abnormality determination with high accuracy, and the result of abnormality determination is not easily affected by changes in the operating status of other motors that share a power source with the motor that drives the machine equipment to be subjected to abnormality determination. It is an object of the present invention to provide an equipment abnormality determination device and an equipment abnormality determination method.

  According to a first aspect of the present invention, there is provided a current detecting means for detecting a load current supplied to an electric motor for driving mechanical equipment, and the electric motor for supplying the electric load to the electric motor. Among the voltage components of each frequency forming the load voltage applied to the frequency, the frequency having the largest voltage component and at least one of the frequencies having the voltage component greater than or equal to the first threshold value as the removal frequency A removal frequency determining means for determining; a removing means for removing a current component of the removal frequency from a current component of each frequency forming the load current detected by the current detecting means; and a removal frequency of the removal frequency by the removing means. First determination means for determining whether or not the load current from which the current component has been removed includes a current component having a magnitude greater than or equal to a second threshold value, and the first determination means When it is determined to include the current component of size greater than the threshold value, to provide a malfunction determining device for a machinery, characterized in that it comprises an abnormality determination means for determining an abnormality of the mechanical equipment.

  The abnormality determination device for mechanical equipment according to the present invention has a current greater than or equal to a second threshold value to the load current from which the current component of the removal frequency has been removed by the removal means (hereinafter referred to as “the post-removal load current”). It is determined whether or not a component is included. If it is determined that the component is included, it is determined that there is an abnormality in the mechanical equipment driven by the electric motor. In order to supply a load current to the electric motor, the removal frequency is a frequency having the largest voltage component among the voltage components forming the load voltage applied to the electric motor, and the voltage component having the first magnitude. At least one of the frequencies above the threshold. That is, the removal frequency is a frequency of a voltage component having a relatively large size among the voltage components forming the load voltage. When the mechanical equipment is normal, the load voltage and the load current having the same frequency have a positive correlation. Therefore, the magnitude of the current component of the removal frequency is relatively large when the mechanical equipment is normal, and the magnitude of the current component forming the post-removal load current is relatively small when the mechanical equipment is normal. Therefore, when the post-removal load current includes a current component that is relatively large (greater than or equal to the second threshold), it can be determined that the mechanical equipment is abnormal. Therefore, the abnormality determination apparatus for mechanical equipment according to the present invention can determine abnormality of mechanical equipment driven by the electric motor.

  As described above, the magnitude of the current component forming the post-removal load current is relatively small when the mechanical equipment is normal. When the mechanical equipment is normal, the current component having a relatively small magnitude has a small change rate because the magnitude of the current component itself is small even when an abnormality having a small effect on the magnitude of the load current occurs. Relatively large. Therefore, the abnormality determination device for mechanical equipment according to the present invention can easily detect an abnormality having a small influence on the magnitude of the load current. Therefore, the abnormality determination apparatus for mechanical equipment according to the present invention can perform abnormality determination with high accuracy.

  In addition, even if the operating status of the motor that drives the mechanical equipment subject to abnormality determination and other motors that share the power supply change, the magnitude of the voltage component among the current components that form the load current is relatively Small frequency current components are unlikely to fluctuate. Therefore, the post-removal load current from which the current component of the removal frequency having a relatively large voltage component has been removed is unlikely to change even if the operating conditions of other motors or the like change. Therefore, the abnormality determination device for mechanical equipment according to the present invention that determines the abnormality of the mechanical equipment based on the load current after removal is less susceptible to the result of the abnormality determination due to changes in the operating status of other motors and the like.

Preferably, as described in claim 2 of the claims, when the basic frequency of the load voltage is f and the positive integer is α (f> α), the current component of the removal frequency is removed by the removal means. A second determination unit that determines whether or not the load current thus satisfied satisfies the following conditions (1) and (2) at the same time, and when the second determination unit determines that the load current is not satisfied, Re-detects the load current, and the removal means removes the current component of the removal frequency from the re-detected load current, and the second determination means determines that the load current is satisfied. 1 determination means determines whether or not the load current from which the current component of the removal frequency has been removed by the removal means determined to be satisfied by the second determination means includes a current component equal to or higher than a second threshold value. Size It is set as the structure which performs interruption.
(1) ... f ± α is a diagnostic frequency that forms the load current from which the current component of the removal frequency has been removed by the removal means and has a current component whose magnitude is not less than a third threshold value. It must be included together.
(2) The diagnostic frequency of 3f or more among the diagnostic frequencies exists at an interval that is an integral multiple of f.

  According to such a preferable configuration, when the load current from which the current component of the removal frequency is removed by the removal means (the load current after removal) does not satisfy the conditions (1) and (2) at the same time, the current detection means detects the load current. Try again. As described above, when the conditions (1) and (2) are not satisfied at the same time, the load current is detected again when the conditions (1) and (2) are not satisfied at the same time. This is because the current detection means does not accurately detect the load current due to the occurrence of a fault or a failure of the current detection means itself. This is because both the frequency f ± α is included in the diagnostic frequency that forms the load current and has a current component that is relatively large (greater than or equal to the third threshold value), and for diagnostic purposes. This is because a diagnostic frequency of 3f or more of the frequencies exists at intervals of an integral multiple of f. Note that the post-removal load current is used as the determination target whether or not the conditions (1) and (2) are satisfied simultaneously. As described above, the post-removal load current varies depending on the operating conditions of other motors and the like. This is because it is difficult to change.

  According to a third aspect of the present invention, there is provided a current detection step for detecting a load current supplied to an electric motor that drives mechanical equipment, and a method for supplying the load current to the electric motor. Of the voltage components of each frequency forming the load voltage applied to the motor, at least one of the frequency having the largest voltage component and the frequency having the voltage component greater than or equal to the first threshold is removed. A removal frequency determination step for determining a frequency, a removal step for removing a current component of the removal frequency from a current component of each frequency forming the load current detected by the current detection step, and the removal by the removal step. A first determination step for determining whether or not the load current from which the frequency current component has been removed includes a current component having a magnitude greater than or equal to a second threshold value; and the first determination step. And an abnormality determination step of determining that the machine equipment is abnormal when it is determined that a current component having a magnitude greater than or equal to a second threshold value is included. .

  According to the present invention, the abnormality determination result is affected by a change in the operation status of the electric motor that drives the mechanical equipment that is the target of the abnormality determination and the other electric motor that shares the power supply with the abnormality determination with high accuracy. It is possible to provide a machine equipment abnormality determination device and a machine equipment abnormality determination method that are difficult.

  FIG. 1 is a functional block diagram of a machine facility abnormality determination apparatus 1 according to the present embodiment. As shown in FIG. 1, the abnormality determination device 1 for mechanical equipment includes a current detection unit 2, a removal frequency determination unit 6, a removal unit 7, a first determination unit 9, and an abnormality determination unit 10. Furthermore, the machine facility abnormality determination device 1 includes a current A / D conversion unit 3, a voltage detection unit 4, a voltage A / D conversion unit 5, a second determination unit 8, an alarm unit 11, and a display unit 12.

The current detection unit 2 detects a load current I ₀ supplied from the power source 103 to the electric motor 102 that drives the mechanical equipment 101. The load current I ₀ is a current that flows from the power source 103 to the motor 102 through the signal cable 104 that connects the motor 102 and the power source 103. As the current detection means 2, for example, a current clamp probe (overhead ammeter) that is inserted into the load current circuit of the electric motor 102 and detects the load current can be used. The machine equipment 101 is not particularly limited, and can be a rotary machine such as a blower, a pump, and a belt conveyor driving device.

The current A / D conversion unit 3 performs A / D conversion on the load current I ₀ detected by the current detection unit 2.

The voltage detection unit 4 detects a load voltage applied to the motor 102 by the power source 103 in order to supply the load current I ₀ to the motor 102.

  The voltage A / D conversion means 5 performs A / D conversion on the load voltage detected by the voltage detection means 4.

  The removal frequency determination means 6 is a frequency having the largest voltage component magnitude (spectrum strength) among the voltage components of each frequency forming the load voltage A / D converted by the voltage A / D conversion means 5, and Then, at least one of the frequencies having a voltage component magnitude equal to or higher than the first threshold is determined as a removal frequency. The removal frequency is determined as follows. The removal frequency determination means 6 first performs frequency analysis on the load voltage A / D converted by the voltage A / D conversion means 5, and the frequency spectrum of the load voltage (hereinafter referred to as "voltage spectrum") as shown in FIG. ) The frequency analysis can be performed by a known Fourier transform (FFT) method. Moreover, the voltage spectrum shown in FIG. 2 is a voltage spectrum of Example 1 mentioned later. Next, the removal frequency determining means 6 determines at least one of the frequency having the largest voltage component and the frequency having the voltage component greater than or equal to the first threshold TH1 in the voltage spectrum as the removal frequency. . In FIG. 2, the frequency with a circle is the frequency with the largest voltage component, and the frequency with a cross is a frequency with the voltage component having a magnitude equal to or greater than the first threshold value TH1. In FIG. 2, the frequency marked with ◯ is the frequency having the largest voltage component and the voltage component magnitude equal to or higher than the first threshold value TH1. In FIG. 2, for ease of viewing, the frequency in the vicinity of the frequency with a circle is marked with × even if the magnitude of the voltage component is a frequency greater than the first threshold value TH1. Absent. The first threshold value TH1 is recorded on a recording medium that can be read by the removal frequency determining means 6. Such a first threshold value TH1 can be set to 160 dB, for example.

Further, the removal frequency may be a frequency included in a range defined by the upper limit value X and the lower limit value X calculated by the following equation (1).
X = fp ± (f ² / (2 × fp) × β) (1)
The fp in the expression (1) is the frequency component having the largest voltage component among the voltage components of each frequency forming the load voltage A / D converted by the voltage A / D conversion means 5, and the voltage component is At least one of the frequencies equal to or higher than the first threshold value TH1. That is, in FIG. 2, it is at least one of the frequency with a circle and the frequency with a cross. F in Expression (1) is a power supply frequency, that is, a fundamental frequency of a load voltage applied to the motor 102 by the power supply 103. Β in Equation (1) is a coefficient that satisfies 0 <β <1.

The removal means 7 removes the current component of the removal frequency from the current component of each frequency forming the load current I ₀ detected by the current detection means 2. The removal of the current component of the removal frequency is performed as follows. The removing unit 7 first analyzes the frequency of the load current I ₀ A / D converted by the current A / D converting unit 3, and the frequency spectrum of the load current as shown in FIG. 3 (hereinafter referred to as “current spectrum”). ) The frequency analysis can be performed by a known Fourier transform (FFT) method. Moreover, the current spectrum shown in FIG. 3 is a current spectrum of Example 1 described later. Next, the removal means 7 removes the current component of the removal frequency from the load current I ₀ A / D converted by the current A / D conversion means 3 using the current spectrum. FIG. 4 shows a frequency spectrum of the post-removal load current from which the current component of the removal frequency has been removed by the removal means 7 (hereinafter referred to as “post-removal load current spectrum”). The post-removal load current spectrum shown in FIG. 4 is a post-removal load current spectrum of Example 1 described later. The post-removal load current spectrum in FIG. 4 is the post-removal load current spectrum obtained when the frequency with ◯ and the frequency with x in FIG.

The second determination means 8 determines whether or not the load current after removal satisfies the following conditions (1) and (2) simultaneously, where f is the basic frequency of the load voltage and α is a positive integer (f> α). to decide.
(1) ... f ± α is included in the diagnostic frequency that forms the post-removal load current and has a current component whose magnitude is equal to or greater than the third threshold value TH3.
(2) The diagnostic frequency of 3f or more among the diagnostic frequencies exists at intervals of an integral multiple of f.
In the condition (1), if the basic frequency f of the load voltage is 60 Hz, the difference with respect to 60 Hz is the same as 0 Hz and less than 60 Hz, and both the frequency exceeding 60 Hz and less than 120 Hz. Refers to the frequency. In addition, in the post-removal load current of Example 1 showing the post-removal load current spectrum in FIG. 4, there are 1 to 7 diagnostic frequencies having a current component whose magnitude is equal to or greater than the third threshold value TH3. In the first embodiment, the basic frequency f of the load voltage is 60 Hz. Therefore, the diagnostic frequency 1 is 30 (f-30) Hz, and the diagnostic frequency 2 is 90 (f + 30) Hz. The load current after removal includes a diagnostic frequency of f ± α (here, 30). Therefore, the post-removal load current in Example 1 satisfies the condition (1).

  Condition (2) is that, for example, if the basic frequency f of the load voltage is 60 Hz, diagnostic frequencies of 180 Hz or more exist at intervals of (60 Hz × K (K: positive integer)). Means. As described above, in Example 1, the basic frequency f of the load voltage is 60 Hz. Therefore, among the diagnostic frequencies 1 to 7 shown in FIG. 4, the diagnostic frequency 4 (1013 Hz), the diagnostic frequency 5 (1133 Hz), diagnostic frequency 6 (1373 Hz), and diagnostic frequency 7 (1493 Hz) are diagnostic frequencies of 3f or more. The interval between the diagnostic frequency 4 and the diagnostic frequency 5 is 120 (60 × 2) Hz, the interval between the diagnostic frequency 5 and the diagnostic frequency 6 is 240 (60 × 4) Hz, the diagnostic frequency 6 and the diagnostic frequency 7 is 120 (60 × 2) Hz, and thus the load current after removal in Example 1 satisfies the condition (2).

When it is determined that the above conditions (1) and (2) are not satisfied at the same time, the current detection means 2 re-detects the load current I ₀ , and the removal means 7 starts from the re-detected load current I _0. The current component of the removal frequency is removed. Thus, the post-removal load current from which the current component of the removal frequency has been removed by the removal means 7 is again judged by the second determination means 8 whether or not the above conditions (1) and (2) are simultaneously satisfied. The

As described above, when the conditions (1) and (2) are not satisfied at the same time, the load current I ₀ is detected again when the conditions (1) and (2) are not satisfied at the same time. This is because the current detection unit 2 cannot accurately detect the load current I ₀ due to noise from the current detection unit or a failure of the current detection unit itself. This is because the diagnostic frequency that forms the load current I ₀ and has a current component that is relatively large (greater than or equal to the third threshold value TH3) includes both frequencies f ± α, This is because, among the diagnostic frequencies, diagnostic frequencies of 3f or more exist at intervals of an integral multiple of f. As shown in FIG. 4, the third threshold value TH3 can be set to 110 dB, for example.

The load current I ₀ has a relatively large current component at a frequency in the vicinity of f ± f / (number of poles (number of poles) / 2 of the motor 102). Therefore, α in the condition (1) can be f / (number of poles of the motor 102/2). When α in the condition (1) is f / (number of poles of the motor 102/2), when the number of poles of the motor is 4 and the basic frequency f of the load voltage is 60 Hz, the condition 1 f ± α is 60 / (4/2), that is, 60 ± 30 Hz.

  The basic frequency f of the load voltage, the third threshold value TH3, and the number of poles of the electric motor 102 are recorded in a record (not shown) that can be read by the second determination means 8.

  The first determination unit 9 determines whether or not the post-removal load current determined to be satisfied by the second determination unit 8 includes a current component having a magnitude greater than or equal to the second threshold value TH2. In the present embodiment, whether or not a current component having a magnitude equal to or greater than the second threshold value TH2 is included is a current component of the diagnostic frequency among the current components that form the post-removal load current. It is said. The second threshold value TH2 is recorded in a record (not shown) that can be read by the first determination means 9.

The abnormality determining means 10 determines that the mechanical equipment 101 is abnormal when it is determined by the first determining means 9 that the post-removal load current includes a current component equal to or greater than the second threshold value TH2. The determination can be made as follows. After removal load current, in which current component rejection frequency from the load current I ₀ has been removed. The removal frequency is at least one of the frequency having the largest voltage component among the voltage components forming the load voltage and the frequency having the voltage component having the first threshold value or more. That is, the removal frequency is a frequency of a voltage component having a relatively large size among the voltage components forming the load voltage. When the mechanical equipment 101 is normal, the load voltage and the load current having the same frequency have a positive correlation. Therefore, the magnitude of the current component of the removal frequency is relatively large when the mechanical equipment 101 is normal, and the magnitude of the current component forming the post-removal load current is relatively small when the mechanical equipment 101 is normal. Therefore, when the post-removal load current includes a current component that is relatively large (greater than or equal to the second threshold value TH2), it can be determined that the mechanical equipment 101 is abnormal. When the abnormality of the mechanical equipment 101 occurs, the second threshold value TH2 is set to, for example, an abnormality of the mechanical equipment 101 so that a current component greater than or equal to the second threshold value TH2 is included in the post-removal load current. Only when this occurs, the current component included in the post-removal load current is set to a magnitude that can be exceeded.

  When the abnormality determination unit 10 determines that the mechanical equipment 101 is abnormal, the warning means 11 emits an alarm sound or the like that notifies the abnormality of the mechanical equipment 101. When the abnormality determining means 10 determines that the mechanical equipment 101 is abnormal, the display means 12 displays on the screen of a monitor (not shown) that an abnormality of the mechanical equipment 101 has occurred.

  Next, the abnormality determination procedure of the mechanical equipment 101 performed by the mechanical equipment abnormality determination device 1 according to the present embodiment described above will be described. FIG. 5 is a flowchart showing an abnormality determination procedure for the machine equipment 101 performed by the machine equipment abnormality determination device 1 according to the present embodiment.

  First, the abnormality determination device 1 for mechanical equipment performs initial setting (FIG. 5, S501). In this initial setting, the second determination means 8 uses the basic frequency f of the load voltage, the third threshold TH3, and the storage medium in which the number of poles of the motor 102 is stored, the basic frequency f of the load voltage, The third threshold value TH3 and the number of poles of the electric motor 102 are read, and the first determination means 9 reads the second threshold value TH2 from the storage medium storing the second threshold value TH2. It should be noted that the frequency where the magnitude of the voltage component is greater than or equal to the first threshold TH1 is determined as the removal frequency, the frequency where the magnitude of the voltage component is the largest, and the magnitude of the voltage component is the first threshold TH1. In the case where the above frequency is determined as the removal frequency, in the initial setting, the removal frequency determination means 6 reads the first threshold value TH1 from the recording medium in which the first threshold value TH1 is stored.

When the initial setting is performed, the current detection unit 2 detects the load current I ₀ (FIG. 5, S502). When the load current I ₀ is detected by the current detection unit 2, the current A / D conversion unit 3 performs A / D conversion on the detected load current I ₀ (FIG. 5, S503). Then, removing means 7, the load current _{I 0} of A / D conversion from the current A / D converter 3 and the frequency analysis to obtain the current spectra as shown in FIG. 3 (FIG. 5, S504).

  Next, the voltage detection means 4 detects a load voltage (FIG. 5, S505). When the load voltage is detected by the voltage detection unit 4, the voltage A / D conversion unit 5 performs A / D conversion on the detected load voltage (S506 in FIG. 5). Next, the removal frequency determination means 6 performs frequency analysis on the load voltage A / D converted by the voltage A / D conversion means 5 (FIG. 5, S507), and determines the removal frequency (FIG. 5, S508). Steps S502 to S504 in FIG. 5 and steps S505 to S508 in FIG. 5 may be performed first or both may be performed simultaneously.

When the removal frequency is determined, the removal unit 7 removes the current component of the removal frequency from the current component of each frequency forming the load current I ₀ A / D converted by the current A / D conversion unit 3. A post-removal current spectrum as shown in FIG. 5 is obtained (FIG. 5, S509).

Next, the second determination means 8 determines whether or not the post-removal load current satisfies the above conditions (1) and (2) at the same time. In order to make this determination, first, the second determination means 8 uses the post-removal current spectrum to specify the diagnostic frequency (the frequency of the current component having a magnitude equal to or greater than the third threshold value TH3) (FIG. 5, S510). Next, it is simultaneously satisfied that the diagnostic frequency includes both f ± α and that the diagnostic frequency that is 3f or more of the diagnostic frequencies exists at intervals of an integral multiple of f. It is determined whether it has been performed (FIG. 5, S511). This determination, whether the current detection means 2 to accurately detect the load current I ₀ is judged.

In decision S511, if it is determined not satisfied, it starts over from the detection of the load current _{I 0} (Fig. 5, S502~S510). In the case re-detection of the load current I ₀ is the detection of the load voltage, even if re may not re.

  When it is determined that the condition is satisfied in the determination step S511, the first determination unit 9 determines whether or not the current component equal to or greater than the second threshold value TH2 is included in the post-removal load current (FIG. 5, S512).

  If it is determined in the determination step 512 that the post-removal load current includes a current component equal to or greater than the second threshold value TH2, the abnormality determination means 10 determines that the mechanical equipment 101 is abnormal (FIG. 5, S513). ). If it is determined that the mechanical equipment 101 is abnormal, the alarm means 11 emits an alarm sound or the like notifying the abnormality of the mechanical equipment 101, and the display means 12 displays on the monitor screen that the abnormality of the mechanical equipment 101 has occurred ( FIG. 5, S514).

  On the other hand, if it is determined in the determination step 512 that the post-removal load current does not include a current component equal to or greater than the second threshold value TH2, the abnormality determination unit 10 determines that the mechanical equipment 101 is normal (FIG. 5). , S515).

As described above, the machine equipment abnormality determination device 1 according to the present embodiment determines whether or not a current component equal to or greater than the second threshold value TH2 is included in the post-removal load current. It is determined that the mechanical equipment 101 driven by the electric motor 102 is abnormal. As described above, the current component of the removal frequency is a relatively large current component when the mechanical equipment 101 is normal. Therefore, the current component forming the post-removal load current obtained by removing the current component of the removal frequency from the load current I ₀ is relatively small when the mechanical equipment 101 is normal. When the mechanical equipment 101 is normal, a relatively small current component has a relatively large change rate because the current component itself is small even when an abnormality having a small effect on the magnitude of the load current occurs. Therefore, the abnormality determination device 1 for mechanical equipment according to the present embodiment can easily detect an abnormality having a small influence on the magnitude of the load current. Therefore, the machine equipment abnormality determination device 1 according to the present embodiment can perform abnormality determination with high accuracy.

In addition, even if the operating conditions of other motors that share the motor 102 and the power source 103 change, among the current components forming the load current I ₀ , the current component having a frequency with a relatively small voltage component is unlikely to fluctuate. That is, even if the operation status of other electric motors or the like changes, the current component whose frequency is not the removal frequency hardly changes. Accordingly, the post-removal load current is unlikely to change even if the operating conditions of other electric motors or the like change. Therefore, the abnormality determination device 1 for mechanical equipment according to the present embodiment is less likely to be affected by the abnormality determination result due to changes in the operating conditions of other motors that share the electric motor 102 and the power source 103.

  In the present embodiment, the voltage detection unit 4 detects the load voltage applied to the motor 102, but the load voltage detected by the voltage detection unit 4 is not limited to the load voltage. Examples of the load voltage detected by the voltage detection unit 4 include a load voltage having the same voltage component as the load voltage applied to the electric motor 102. Examples of the load voltage having the same voltage component configuration as the load voltage applied to the motor 102 include a load voltage applied by the power source 103 to another motor sharing the motor 102 and the power source 103.

  Further, in this embodiment, the removal frequency determination means 6 performs frequency analysis on the load voltage and determines the removal frequency, but when the analysis result obtained by frequency analysis of the load voltage is recorded on the recording medium, Instead of frequency analysis of the load voltage, the analysis result may be read from the recording medium. When reading the analysis result from the recording medium, the machine equipment abnormality determination device 1 need not include the voltage detection means 4 and the voltage A / D conversion means 5.

  In this example, an abnormality was generated in the mechanical equipment, and the abnormality determination device for the mechanical equipment was determined about the abnormality of the mechanical equipment. FIG. 6A is a schematic configuration diagram of an electric motor and mechanical equipment (blower) driven by the electric motor in the present embodiment and Example 2 described later. As shown in FIG. 6A, the blower 20 is connected to the electric motor 40 via the first rotating shaft member 31 and the second rotating shaft member 32. The first rotating shaft member 31 is a rotating shaft of a rotary blade included in the blower 20, and the second rotating shaft member 32 is a rotating shaft of the electric motor 40. The first rotating shaft member 31 and the second rotating shaft member 32 are connected by a coupling member 60 such as a flanged shaft joint. Further, the first rotating shaft member 31 is supported by two bearings 51 and 52 disposed between the blower 20 and the electric motor 40.

  The abnormality of the mechanical equipment in the present embodiment is vibration of the blower 20 that occurs when the rotary blades of the blower 20 rotate. FIG. 6B is a front view of the rotary blade 21 provided in the blower 20. In the present embodiment, in order to generate such an abnormality, as shown in FIG. 6B, the weight 23 is placed at one place off the center 22 of the rotary blade 21 of the blower 20. The electric motor 40 in this embodiment has an output of 5.5 kw and a pole number of 4. In this embodiment, the basic frequency of the load voltage is 60 Hz. In the present embodiment, the first threshold value TH1 is 160 dB, the second threshold value TH2 is 140 dB, and the third threshold value TH3 is 110 dB. The voltage spectrum of the load voltage, the current spectrum before removal of the current component of the removal frequency, and the current spectrum of the load current after removal in this embodiment are as shown in FIGS.

As described in the embodiment, the post-removal load current in Example 1 satisfies the conditions (1) and (2) for determining whether or not the second determination unit satisfies simultaneously. Therefore, in this embodiment, the current detection means 2 accurately detects the load current.

  Further, as shown in FIG. 4, the current components of the frequencies 30 Hz, 90 Hz, 1133 Hz, and 1373 Hz that form the post-removal load current were equal to or higher than the second threshold value TH2. As described above, since the load current after the removal includes a current component equal to or higher than the second threshold value TH2, when the rotating blade 21 of the blower 20 rotates and vibration of the blower 20 occurs, an abnormality determination device for mechanical equipment Was determined to be an abnormality in the mechanical equipment.

  Further, in the present embodiment, when the amplitude of vibration of the blower 20 when the rotary blade 21 of the blower 20 is rotated is 20 μm, 50 μm, and 70 μm, currents having frequencies of 1133 Hz and 1373 Hz that form a post-removal load current, respectively. The component size was measured. The amplitude of the vibration of the blower was changed by changing the weight of the weight 23 placed at one place off the center 22 of the rotary blade 21 of the blower 20. Further, the vibration amplitude of the blower 20 was measured with a vibration meter attached to the bearing 51 or the bearing 52 disposed between the blower 20 and the electric motor 40. As shown in FIG. 6 (c), in any current component at frequencies 1133 Hz and 1373 Hz, it increased as the amplitude of vibration increased. Therefore, since the value of the current component increases as the amplitude of vibration increases, the abnormality determination of the mechanical equipment according to the present invention is determined to determine that the mechanical equipment is abnormal if there is a current component equal to or greater than the second threshold value TH2. According to the apparatus, it is possible to determine abnormality of mechanical equipment.

  In this embodiment, the weight is not placed 23 at one place off the center 22 of the rotary blade 21 of the blower 20, but a cup between the blower 20 and the electric motor 40 as shown in FIG. In the ring member 60, the core 31a of the first rotating shaft member 31 and the core 32a of the second rotating shaft member 32 are shifted (misalignment) to cause an abnormality in the mechanical equipment. In the present embodiment, the frequency components forming the post-removal load current are 30 Hz and 90 Hz, and the current component is equal to or greater than the second threshold TH2. Further, in this embodiment, when the deviation of the core in the coupling member 60 is set to 0 mm, 0.1 mm, 0.2 mm, and 0.4 mm, the frequency for forming the load current after removal in each core deviation is 30 Hz, The magnitude of the 90 Hz current component was measured. As shown in FIG. 7B, in any current component having a frequency of 30 Hz or 90 Hz, the larger the amount of misalignment in the coupling member 60, the larger the current component. Therefore, as in the first embodiment, the larger the vibration amplitude, the larger the value of the current component. Therefore, according to the machine equipment abnormality determination device according to the present invention, the machine equipment abnormality determination can be performed. it can.

FIG. 1 is a functional block diagram of a machine facility abnormality determination device according to an embodiment. FIG. 2 is a voltage spectrum in the first embodiment. FIG. 3 is a current spectrum of the load current before the current component of the removal frequency is removed in the first embodiment. FIG. 4 is a current spectrum of the post-removal load current in Example 1. FIG. 5 is a flowchart showing a procedure for determining whether or not the mechanical equipment is abnormal, which is performed by the mechanical equipment abnormality determining device. FIG. 6A is a schematic configuration diagram of the electric motor and the blower driven by the electric motor in the first and second embodiments. FIG.6 (b) is a front view of the rotary blade with which the blower shown to Fig.6 (a) is provided. FIG. 6C is a test result showing the magnitude of the current component of each frequency included in the post-removal load current. Fig.7 (a) is the figure which expanded the coupling member, the electric motor, and the blower vicinity of Fig.6 (a). FIG. 7B is a test result showing the magnitude of the current component of each frequency included in the post-removal load current.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Mechanical equipment abnormality determination apparatus, 2 ... Current detection means, 6 ... Removal frequency determination means, 7 ... Removal means, 9 ... First judgment means, 10 ... Abnormality judgment means

Claims (3)

Current detection means for detecting a load current supplied to an electric motor that drives the mechanical equipment;
Of the voltage components of each frequency forming the load voltage applied to the motor to supply the load current to the motor, the frequency having the largest voltage component and the magnitude of the voltage component are first. A removal frequency determining means for determining at least one of the frequencies equal to or higher than the threshold as a removal frequency;
Removing means for removing the current component of the removal frequency from the current component of each frequency forming the load current detected by the current detection means;
First determination means for determining whether or not the load current from which the current component of the removal frequency has been removed by the removal means includes a current component having a magnitude greater than or equal to a second threshold value;
An abnormality of the mechanical equipment, comprising: an abnormality determining means for determining that an abnormality of the mechanical equipment is detected when the first judging means determines that a current component having a magnitude equal to or greater than a second threshold value is included. Judgment device. When the basic frequency of the load voltage is f and the positive integer is α (f> α), the load current from which the current component of the removal frequency has been removed by the removal means satisfies the following conditions (1) and (2). A second judging means for judging whether or not the user is satisfied at the same time;
If it is determined that the second determination means is not satisfied,
The current detection means re-detects the load current, and the removal means removes a current component of the removal frequency from the re-detected load current,
If it is determined that the second determination means is satisfied,
The first determination means determines whether the load current from which the current component of the removal frequency has been removed by the removal means determined to be satisfied by the second determination means includes a current component equal to or higher than a second threshold value. The machine equipment abnormality determination device according to claim 1, wherein the determination is performed.
(1) ... f ± α is a diagnostic frequency that forms the load current from which the current component of the removal frequency has been removed by the removal means and has a current component whose magnitude is not less than a third threshold value. It must be included together.
(2) The diagnostic frequency of 3f or more among the diagnostic frequencies exists at an interval that is an integral multiple of f. A current detection step for detecting a load current supplied to an electric motor that drives the mechanical equipment;
Of the voltage components of each frequency forming the load voltage applied to the motor to supply the load current to the motor, the frequency having the largest voltage component and the magnitude of the voltage component are first. A removal frequency determination step of determining at least one of the frequencies equal to or higher than the threshold as a removal frequency;
A removal step of removing a current component of the removal frequency from a current component of each frequency forming the load current detected by the current detection step;
A first determination step of determining whether or not the load current from which the current component of the removal frequency has been removed by the removal step includes a current component having a magnitude greater than or equal to a second threshold;
An abnormality of the mechanical equipment, including an abnormality determination step of determining that the abnormality of the mechanical equipment is detected when the first judgment step determines that a current component having a magnitude greater than or equal to a second threshold value is included. Judgment method.