Rotating machine and control method therefor

Abstract

To detect an electrolytic corrosion risk with high accuracy in a rotating machine and a control method therefor.SOLUTION: A compressor 1 comprises: a rotary shaft member 10 of a motor 2; a bearing 11 which rotatably supports the rotary shaft member 10; a first parameter acquisition unit which acquires, as a first parameter, an electrical state value between the rotary shaft member 10 and a ground portion 14; a second parameter acquisition unit which acquires, as a second parameter, an impedance related to the bearing 11; and a control device 9 which outputs an electrical signal upon determining that the first parameter is in an abnormal state when the first parameter exceeds a threshold a predetermined number of times or when a rate of change of the first parameter exceeds a reference value, and outputs an electrical signal upon determining that the second parameter is in an abnormal state when the second parameter is less than the threshold in a case where the first parameter is not in the abnormal state.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a rotating machine and a control method thereof. [Background technology]

[0002] Electrical corrosion of motors and bearings in rotating machinery such as compressors and fans can lead to a shortened product life, increased noise, and product failure, so it is an important factor that must be monitored for preventive maintenance and stable operation.

[0003] Patent Document 1 discloses a fan filter unit that allows for easy detection of when abnormal motor noise occurs due to electrolytic corrosion, which accounts for a large percentage of breakdowns, and facilitates regular inspections and advance planning. The fan unit measures the potential difference between the outer shell of the bearing and the outer casing of the rotating shaft member, and monitors electrolytic corrosion based on this potential difference. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2019-132508 Summary of the Invention [Problem to be solved by the invention]

[0005] However, in Patent Document 1, the presence or absence of electrolytic corrosion is determined solely based on the potential difference between the outer shell of the bearing and the outer casing of the rotating shaft member, so there is room for improvement in the accuracy of detecting the risk of electrolytic corrosion.

[0006] An object of the present invention is to detect the risk of electrolytic corrosion with high accuracy in a rotating machine and a control method thereof. [Means for solving the problem]

[0007] A first aspect of the present invention is a rotating shaft member of the motor; a bearing that rotatably supports the rotary shaft member; a first parameter acquisition unit that acquires an electrical state value between the rotating shaft member and a grounding portion as a first parameter; a second parameter acquisition unit that acquires an impedance related to the bearing as a second parameter; a control device that determines that the first parameter is in an abnormal state when the first parameter exceeds a threshold value a predetermined number of times or when a rate of change of the first parameter exceeds a reference value, and outputs an electric signal; and that determines that the second parameter is in an abnormal state when the second parameter becomes less than a threshold value while the first parameter is not in an abnormal state, and outputs an electric signal; A rotary machine comprising:

[0008] According to the above configuration, since the presence or absence of a risk of electrolytic corrosion of the motor is determined based on both the first parameter and the second parameter, the risk of electrolytic corrosion of the motor can be detected with high accuracy. Therefore, measures to reduce electrolytic corrosion can be taken early, and damage to the motor of a rotating machine such as a compressor or a fan can be reduced.

[0009] The electrical state value may be a potential difference between the end of the rotating shaft member and the ground portion, or may be an impedance between the end of the rotating shaft member and the ground portion.

[0010] The occurrence of a potential difference or a decrease in impedance can cause a current to flow through the bearing, resulting in electrolytic corrosion. According to the above configuration, the potential difference and impedance as the first parameter are easy to measure, so electrolytic corrosion can be detected with high accuracy using a simple configuration.

[0011] The bearing may have an inner ring and an outer ring. The second parameter may be an impedance between the inner ring and the outer ring of the bearing. The second parameter may be an impedance between the outer ring of the bearing and the end of the rotating shaft member.

[0012] According to the above configuration, the impedance as the second parameter is easy to measure, so electrolytic corrosion can be detected with high accuracy using a simple configuration.

[0013] The rotating machine may further include an alarm unit that receives the electrical signal and issues an alarm.

[0014] According to the above configuration, the risk of electrolytic corrosion can be easily recognized by the alarm from the alarm unit.

[0015] The alarm unit may have a display screen. The control device may cause the alarm unit to issue an alarm and may also cause the display screen to display a maintenance method for improving the first parameter or the second parameter.

[0016] According to the above configuration, the user can easily check the maintenance method and easily improve the first parameter or the second parameter. For example, the maintenance method may be to prompt the user to check the grounding state of the earth, to prompt the user to replenish grease in the bearing, or to prompt the user to replace the bearing.

[0017] The rotary machine may further include an inverter that adjusts the rotation speed of the rotary shaft member, The control device may cause the alarm unit to issue an alarm and reduce the carrier frequency of the inverter.

[0018] According to the above configuration, the risk of electrolytic corrosion can be automatically reduced by lowering the carrier frequency of the inverter.

[0019] The rotary machine may further include an inverter that adjusts the rotation speed of the rotary shaft member, The control device may cause the alarm unit to issue an alarm and control the inverter to adjust the rotation speed of the rotating shaft member.

[0020] According to the above configuration, the risk of electrolytic corrosion can be automatically reduced by adjusting the rotation speed of the rotating shaft member. For example, the risk of electrolytic corrosion can be automatically reduced by adjusting the rotation speed so that it does not become constant.

[0021] The predetermined number of times may be a plurality of times.

[0022] According to the above configuration, a case where the first parameter takes a high value in a pulse-like manner only once due to an external factor or the like is not determined to be abnormal, thereby making it possible to suppress erroneous detection of electrolytic corrosion.

[0023] The control device may have a cloud communication function.

[0024] According to the above configuration, various data such as the first parameter and the second parameter acquired from the rotating machine can be managed by the server and effectively used as cloud data. In addition, even if the customer terminal is located in a remote location from the rotating machine, the risk of electrolytic corrosion of the rotating machine can be recognized.

[0025] A second aspect of the present invention is a rotating shaft member of the motor; a bearing that rotatably supports the rotary shaft member; a first parameter acquisition unit that measures an electrical state value between the rotating shaft member and a grounding portion as a first parameter; a second parameter acquisition unit that measures an impedance related to the bearing as a second parameter; A method for controlling a rotary machine comprising: Provided is a control method for a rotating machine, which determines that the first parameter is in an abnormal state and outputs an electrical signal if the first parameter exceeds a threshold value a predetermined number of times or if the rate of change of the first parameter exceeds a reference value, and determines that the second parameter is in an abnormal state and outputs an electrical signal if the second parameter is less than a threshold value when the first parameter is not in an abnormal state. [Effects of the Invention]

[0026] According to the present invention, electrolytic corrosion can be detected with high accuracy in a rotating machine and a control method thereof. [Brief explanation of the drawings]

[0027] [Figure 1] 1 is a schematic configuration diagram of a rotary machine according to a first embodiment. [Figure 2] 1 is a flowchart showing an example of a control method for a rotating machine. [Figure 3] 1 is a graph showing the relationship between axial potential and time. [Figure 4] 10 is a graph showing the relationship between bearing impedance and time. [Figure 5] 10 is a flowchart showing another example of the control method for the rotating machine according to the second embodiment. [Figure 6] 10 is another graph showing the relationship between axial potential and time. [Figure 7] FIG. 10 is a schematic configuration diagram of a rotary machine according to a third embodiment. [Figure 8] FIG. 10 is a schematic configuration diagram of a rotary machine according to a fourth embodiment. [Figure 9] FIG. 10 is a schematic configuration diagram of a rotary machine according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0028] Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

[0029] (First embodiment) Referring to Fig. 1, a rotary machine 1 of this embodiment is a compressor that compresses gas by rotating a load device (screw rotor) 3 with a motor 2. Therefore, hereinafter, the rotary machine 1 will also be referred to as a compressor 1. The gas to be compressed by the compressor 1 is, for example, air, but is not particularly limited to this. Note that Fig. 1 shows an enlarged view of the portion indicated by the dashed circle.

[0030] The compressor 1 of this embodiment has a motor 2, a screw rotor 3, an inverter 4, a terminal block 5, a voltage sensor (first parameter acquisition unit) 6, an impedance sensor (second parameter acquisition unit) 7, an alarm unit 8, and a control device 9. In the figure, the connection wiring of each component is shown, and in particular, the wiring related to the sensors is shown by dashed lines to clarify the illustration.

[0031] The load device 3 is mechanically connected to the motor 2 and generates a given load. In this embodiment, the load device 3 is a screw rotor 3. The screw rotor 3 has a structure in which a pair of male and female rotors rotate and mesh. However, the load device 3 is not limited to the screw rotor 3, and may be any component of the rotating machine 1, such as a fan blade 3. When the load device 3 is a fan blade 3, the rotating machine 1 is a blower.

[0032] The motor 2 is an AC motor that serves as a power source for rotating the screw rotor 3. The motor 2 has a rotating shaft member 10 and a bearing 11. In this embodiment, the bearing 11 is a rolling bearing having an inner ring 11a, an outer ring 11b, and rolling elements 11c. The bearing 11 rotatably supports the rotating shaft member 10. The rotating shaft member 10 extends horizontally, and one end 10a is connected to the screw rotor 3, and the other end 10b is connected to a voltage sensor 6 (described later). The motor 2 has legs 12 for self-support. The legs 12 are electrically connected to a grounding portion 14 via a terminal block 5. The grounding portion 14 is a grounded portion with zero potential. In this embodiment, the rotating shaft member 10 of the motor 2 also serves as the shaft of the screw rotor 3 and is integrally formed with the screw rotor 3. However, one end 10a of the rotating shaft member 10 of the motor 2 may be indirectly connected to the shaft of the screw rotor 3 via a power transmission means such as a gear or a coupling.

[0033] The inverter 4 is electrically connected to the motor 2 by a three-phase, three-wire power distribution system, and is also electrically connected to the power supply 13 via a terminal block 5. The inverter 4 receives input from the power supply 13 and outputs to the motor 2 at a desired frequency and voltage. This allows the inverter 4 to adjust the rotation speed of the motor 2.

[0034] The voltage sensor 6 acquires the electrical state value between the other end 10b of the rotating shaft member 10 and the earth part 14 as a first parameter. In this embodiment, the voltage sensor 6 is electrically connected to the other end 10b of the rotating shaft member 10 and is also electrically connected to the earth part 14 via the terminal block 5. Here, the first parameter is the potential difference between the other end 10b of the rotating shaft member 10 and the earth part 14.

[0035] The impedance sensor 7 acquires the impedance associated with the bearing 11 as the second parameter. In this embodiment, the impedance sensor 7 is electrically connected to the inner ring 11a and the outer ring 11b of the bearing 11. Here, the second parameter is the impedance between the inner ring 11a and the outer ring 11b of the bearing 11.

[0036] The alarm unit 8 is controlled by the control device 9 and issues an alarm in a predetermined case, which will be described later. In this embodiment, the alarm unit 8 has a speaker and a display (display screen) and can output both an alarm sound and an alarm screen. However, the mode of the alarm is not particularly limited.

[0037] The control device 9 performs arithmetic processing and overall control of the compressor 1. The control device 9 includes, for example, a central processing unit (CPU) or a microprocessing unit (MPU) that implements predetermined functions in cooperation with software. The control device 9 may be configured with hardware circuits, such as dedicated electronic circuits or reconfigurable electronic circuits, designed to implement predetermined functions, or may be configured with various semiconductor integrated circuits. Examples of various semiconductor integrated circuits include CPUs, MPUs, microcomputers, digital signal processors (DSPs), field programmable gate arrays (FPGAs), and application-specific integrated circuits (ASICs). The control device 9 may also include storage devices such as random access memory (RAM) and read-only memory (ROM). Specifically, the control device 9 may be configured with an information processing device such as a desktop computer, laptop computer, workstation, or tablet terminal, or a printed circuit board with equivalent functions.

[0038] The control device 9 determines that the first parameter is in an abnormal state when the first parameter exceeds the threshold a predetermined number of times, and outputs an electric signal. The alarm unit 8 that receives the electric signal issues an alarm. Here, the threshold and the predetermined number of times for the first parameter are set appropriately taking into consideration the risk of electrolytic corrosion and the detection accuracy. In this embodiment, the predetermined number is, for example, two times. However, the predetermined number of times may be one time, or three or more times. Furthermore, the control device 9 determines that the second parameter is in an abnormal state when the first parameter is not in an abnormal state and the second parameter is less than the threshold, and outputs an electric signal. The alarm unit 8 that receives the electric signal issues an alarm. Here, the threshold for the second parameter is set appropriately taking into consideration the risk of electrolytic corrosion and the detection accuracy.

[0039] In this embodiment, the control device 9 outputs an electrical signal when the first parameter or the second parameter is determined to be in an abnormal state. When the alarm unit 8 receives the electrical signal, the alarm unit 8 issues an alarm. The control device 9 automatically executes electrolytic corrosion reduction control to reduce the risk of electrolytic corrosion. Specifically, when the first parameter or the second parameter is determined to be in an abnormal state, the control device 9 may output an electrical signal to the inverter 4 and, as electrolytic corrosion reduction control, may lower the carrier frequency of the inverter 4. By lowering the carrier frequency of the inverter 4, it becomes more difficult for current to flow through the motor 2, thereby reducing electrolytic corrosion. Alternatively or in addition to this, the electrolytic corrosion reduction control may adjust the rotation speed of the rotating shaft member 10. Specifically, when the first parameter or the second parameter is determined to be in an abnormal state, the control device 9 may output an electrical signal to the inverter 4 and increase and then decrease the rotation speed of the rotating shaft member 10 of the motor 2 so that it does not remain constant, or may decrease and then increase the rotation speed. In this way, the rotation speed of the rotating shaft member 10 is adjusted so as not to be constant, and the oil film thickness of the bearing is ensured, thereby reducing the risk of electrolytic corrosion.

[0040] A control method for the compressor 1 of this embodiment will be described in detail with reference to FIG.

[0041] When the compressor 1 starts operating (step S2-1), a first parameter Z1 and a second parameter Z2 are measured (step S2-2). In this embodiment, the first parameter Z1 is the potential difference (shaft potential) between the other end 10b of the rotating shaft member 10 and the earth part 14, measured by the voltage sensor 6. The second parameter Z2 is the impedance (bearing impedance) between the inner ring 11a and the outer ring 11b of the bearing 11, measured by the impedance sensor 7. Next, it is determined whether the first parameter Z1 exceeds the threshold value Za a predetermined number of times (twice in this embodiment) within a predetermined time (step S2-3). If the first parameter Z1 exceeds the threshold value Za a predetermined number of times (twice in this embodiment) (Y: step S2-3), it is determined that the first parameter Z1 is in an abnormal state.

[0042] The determination in step S2-3 will be described with reference to the time-series data of the first parameter Z1 (axial potential) in FIG.

[0043] In the illustrated example, the first parameter Z1 (shaft potential) changes over time and occasionally takes a high value. The first parameter Z1 (shaft potential) exceeds the threshold value Za for the first time at time t1 and exceeds the threshold value Za for the second time at time t2. Therefore, the control device 9 determines that the first parameter Z1 is in an abnormal state at time t2.

[0044] Even if the first parameter Z1 is not determined to be in an abnormal state (N: step S2-3), it is determined whether the second parameter Z2 is less than the threshold value Zb (step S2-4), and if the second parameter Z2 is less than the threshold value Zb (Y: step S2-4), it is determined that the second parameter is in an abnormal state.

[0045] The determination in step S2-4 above will be described with reference to the time-series data of the second parameter Z2 (bearing impedance) in FIG.

[0046] The second parameter Z2 (bearing impedance) changes over time and falls below the threshold Zb at time t3. Therefore, the control device 9 determines that the second parameter Z2 is in an abnormal state at time t3. If the second parameter Z2 is not in an abnormal state (N: step S2-4), the first parameter Z1 and the second parameter Z2 are measured again (step S2-2).

[0047] If the first parameter Z1 is in an abnormal state (Y: step S2-3) or the second parameter Z2 is in an abnormal state (Y: step S2-4), an electric signal is output from the control device 9, and an alarm is issued from the alarm unit 8 (step S2-5). The alarm is issued continuously, and while the alarm is being issued, the above-mentioned electrolytic corrosion reduction control is executed (step S2-6). This makes it possible to automatically improve the abnormality of the first parameter Z1 or the second parameter Z2.

[0048] If the first parameter Z1 does not become equal to or less than the threshold value Za and the abnormality of the first parameter is not improved (N: step S2-7), the electrolytic corrosion reduction control is continued (step S2-6). Even if the first parameter Z1 becomes equal to or less than the threshold value Za and the abnormality of the first parameter is improved (Y: step S2-7), if the second parameter Z2 becomes equal to or greater than the threshold value Zb and the abnormality of the second parameter is not improved (N: step S2-8), the electrolytic corrosion reduction control is continued (step S2-6). If the second parameter Z2 becomes equal to or greater than the threshold value Zb and the abnormality of the second parameter is improved (Y: step S2-8), the alarm and the electrolytic corrosion reduction control are stopped (step S2-9), and the first parameter Z1 and the second parameter Z2 are measured again (step S2-2). Then, the processing from step S2-3 onwards is repeated.

[0049] The compressor 1 of this embodiment provides the following advantages.

[0050] Since the presence or absence of electrolytic corrosion is determined using both the first parameter and the second parameter, it is possible to detect with high accuracy the risk of electrolytic corrosion of the motor 2. Therefore, measures to reduce electrolytic corrosion can be taken early, and damage to the motor 2 of the compressor 1 can be reduced.

[0051] Furthermore, since the potential difference between the rotating shaft member 10 and the earth portion 14 as the first parameter is easy to measure, electrolytic corrosion can be detected with high accuracy using a simple configuration.

[0052] Furthermore, the impedance between the inner ring 11a and the outer ring 11b of the bearing 11 as the second parameter is easy to measure, and therefore electrolytic corrosion can be detected with high accuracy using a simple configuration.

[0053] Furthermore, the risk of electrolytic corrosion can be easily recognized by the warning from the warning unit 8.

[0054] In addition, electrolytic corrosion risk can be automatically reduced by electrolytic corrosion reduction control.

[0055] Furthermore, the predetermined number of times for determining whether the first parameter exceeds the threshold is set to multiple times (twice in this embodiment). Therefore, a case where the first parameter takes a high value in a pulse-like manner only once due to an external factor or the like is not determined to be an abnormality, thereby suppressing erroneous detection of electrolytic corrosion.

[0056] As a modification of this embodiment, instead of or in addition to electrolytic corrosion reduction control, the control device 9 may cause the alarm unit 8 to issue an alarm and display a maintenance method for improving the first parameter or the second parameter on a display (display screen) of the alarm unit 8. For example, the maintenance method may be to prompt the user to check the grounding condition of the earthing unit 14, to prompt the user to replenish grease in the bearing 11, or to prompt the user to replace the bearing 11.

[0057] This allows the user to easily check the maintenance method and easily improve the first parameter or the second parameter. For example, the maintenance method may be to prompt the user to check the grounding state of the earth, to prompt the user to replenish grease in the bearing, or to prompt the user to replace the bearing.

[0058] (Second embodiment) In the flowchart of the control method for the compressor 1 of the second embodiment shown in Fig. 5, the handling of the first parameter is different from that of the first embodiment. Other than this, the second embodiment is substantially the same as the first embodiment. Therefore, the description of the parts shown in the first embodiment may be omitted.

[0059] In this embodiment, when the compressor 1 starts operating (step S3-1), the first parameter Z1 and the second parameter Z2 are measured (step S3-2). The first parameter Z1 and the second parameter Z2 themselves are the same as those in the first embodiment. That is, the first parameter Z1 is the potential difference (shaft potential) between the other end 10b of the rotating shaft member 10 and the earth part 14, which is acquired by the voltage sensor 6. The second parameter Z2 is the impedance (bearing impedance) between the inner ring 11a and the outer ring 11b of the bearing 11, which is acquired by the impedance sensor 7. Next, the control device 9 calculates the rate of change Zx of the first parameter Z1 (step S3-3).

[0060] The calculation in step S3-3 will be described with reference to the time-series data of the first parameter Z1 (axial potential) in FIG.

[0061] In the illustrated example, the first parameter Z1 (axis potential) changes over time and gradually increases. The first parameter Z1 (axis potential) takes on a value Z11 at time t4 and a value Z12 at time t5. Therefore, the rate of change Zx of the first parameter Z1 during this period is expressed as (Z12-Z11) / (t5-t4). Then, it is determined whether the rate of change Zx of the first parameter Z1 is greater than a reference value Zc (step S3-4). If the rate of change Zx of the first parameter Z1 is greater than the reference value Zc (Y: step S3-4), it is determined that the first parameter Z1 is in an abnormal state. Here, the reference value Zc is set appropriately taking into account the risk of electrolytic corrosion and detection accuracy.

[0062] Even if the first parameter Z1 is not determined to be in an abnormal state (N: step S3-4), it is determined whether the second parameter Z2 is less than the threshold value Zb (step S3-5), and if the second parameter Z2 is less than the threshold value Zb (Y: step S3-5), it is determined that the second parameter is in an abnormal state.

[0063] The processing relating to steps S3-6 to S3-10 in this embodiment is substantially the same as steps S2-5 to S2-9 in the first embodiment (FIG. 2).

[0064] As in this embodiment, the abnormality determination of the first parameter Z1 can be based not on the value of the first parameter Z1 itself but on the rate of change Zx thereof.

[0065] (Third embodiment) The compressor 1 of the third embodiment shown in Fig. 7 differs from the first embodiment in the measurement location of the impedance sensor (second parameter acquisition unit) 7. Other than this, the compressor 1 is substantially the same as the first embodiment. Therefore, the description of the parts shown in the first embodiment may be omitted.

[0066] In this embodiment, the impedance sensor 7 is electrically connected to the outer ring 11b of the bearing 11 and the other end 10b of the rotating shaft member 10. Here, the second parameter is the impedance between the outer ring 11b of the bearing 11 and the other end 10b of the rotating shaft member 10.

[0067] According to this embodiment, the impedance between the outer ring 11b of the bearing 11 and the other end 10b of the rotating shaft member 10 as the second parameter is easy to measure, and therefore electrolytic corrosion can be detected with high accuracy using a simple configuration.

[0068] (Fourth embodiment) The compressor 1 of the fourth embodiment shown in Fig. 8 differs from the first embodiment in the configuration related to the first parameter. Other than this, the compressor 1 is substantially the same as the first embodiment. Therefore, the description of the parts shown in the first embodiment may be omitted.

[0069] In this embodiment, the voltage sensor 6 (see FIG. 1) of the first embodiment is replaced with an impedance sensor (first parameter acquisition unit) 15. The impedance sensor 15 is electrically connected to the other end 10b of the rotating shaft member 10 and is also electrically connected to the earth part 14 via the terminal block 5. Here, the first parameter is the impedance between the other end 10b of the rotating shaft member 10 and the earth part 14.

[0070] According to this embodiment, the impedance between the other end 10b of the rotating shaft member 10 and the earth part 14 as the first parameter is easy to measure, and therefore electrolytic corrosion can be detected with high accuracy using a simple configuration.

[0071] (Fifth embodiment) The compressor 1 of the fifth embodiment shown in Fig. 9 differs from the first embodiment in that it has a cloud communication function. Other than this, the compressor 1 is substantially the same as the first embodiment. Therefore, the description of the parts shown in the first embodiment may be omitted.

[0072] In this embodiment, the control device 9 has a cloud communication function. That is, the control device 9 is connected to an external device 16 via a network N. For example, the external device 16 is a server having a storage device. The storage device is realized by a flash memory, an SSD (Solid State Device), a hard disk, another storage device, or an appropriate combination thereof. The network N may be the Internet, an intranet, an extranet, a LAN, ISDN, a VAN, a CATV communication network, a virtual private network, a telephone line network, a mobile communication network, a satellite communication network, or the like. The server 16 communicates with the control device 9 via the network N and receives and stores various data related to the first parameter and the second parameter.

[0073] Alternatively, the external device 16 may be a customer terminal for monitoring the status of the compressor 1. The customer terminal may be an information processing device such as a desktop computer, a laptop computer, a workstation, or a tablet computer.

[0074] According to this embodiment, various data such as the first parameter and the second parameter acquired in the compressor 1 can be managed by a server (external device 16) and effectively used as cloud data. Furthermore, even if the customer terminal (external device 16) is located in a remote location, the risk of electrolytic corrosion of the motor 2 can be recognized.

[0075] While specific embodiments of the present invention and their modifications have been described above, the present invention is not limited to the above-described embodiments and can be implemented with various modifications within the scope of the present invention. For example, an appropriate combination of the contents of the individual embodiments may be considered as one embodiment of the present invention.

[0076] Furthermore, in the above embodiment and its modified examples, the inverter 4 may be omitted. That is, the rotation speed of the motor 2 does not need to be adjustable. In this case, electrolytic corrosion reduction control using the inverter 4 is also omitted. [Explanation of symbols]

[0077] 1 Rotating machines (compressors) (fans) 2 motors 3 Load device (screw rotor) (fan blade) 4 inverters 5 Terminal block 6 Voltage sensor (first parameter acquisition unit) 7 Impedance sensor (second parameter acquisition unit) 8 Alarm section 9 Control Device 10 Rotating shaft member 10a One end 10b Other end (end) 11 Bearings 11a Inner Circle 11b outer ring 11c Rolling elements 12 Legs 13 Power supply 14 Earth section 15 Impedance sensor (first parameter acquisition unit) 16 External device (server) (customer terminal)

Claims

1. The rotating shaft member of the motor, A bearing that rotatably supports the aforementioned rotating shaft member, A first parameter acquisition unit acquires the electrical state value between the rotating shaft member and the ground portion as a first parameter, A second parameter acquisition unit that acquires the impedance related to the bearing as a second parameter, A control device that outputs an electrical signal when the first parameter exceeds a first threshold a predetermined number of times or when the rate of change of the first parameter exceeds a reference value, and when the second parameter falls below a second threshold while the first parameter is not in an abnormal state, it determines that the second parameter is in an abnormal state and outputs an electrical signal. A rotating machine equipped with the following features.

2. The rotating machine according to claim 1, wherein the electrical state value is the potential difference between the end of the rotating shaft member and the ground portion.

3. The rotating machine according to claim 1, wherein the electrical state value is the impedance between the end of the rotating shaft member and the ground portion.

4. The bearing has an inner ring and an outer ring, The rotating machine according to any one of claims 1 to 3, wherein the second parameter is the impedance between the inner ring and the outer ring of the bearing.

5. The bearing has an inner ring and an outer ring, The rotating machine according to any one of claims 1 to 3, wherein the second parameter is the impedance between the outer ring of the bearing and the end of the rotating shaft member.

6. The rotating machine according to any one of claims 1 to 3, further comprising an alarm unit that receives the aforementioned electrical signal and issues an alarm.

7. The alarm unit has a display screen, The rotating machine according to claim 6, wherein the control device causes the alarm unit to issue an alarm and displays on the display screen a maintenance method for improving the abnormal state of the first parameter or the second parameter.

8. The system further includes an inverter for adjusting the rotational speed of the aforementioned rotating shaft member. The rotating machine according to claim 6, wherein the control device causes the alarm unit to issue an alarm and reduces the carrier frequency of the inverter.

9. The system further includes an inverter for adjusting the rotational speed of the aforementioned rotating shaft member. The rotating machine according to claim 6, wherein the control device causes the alarm unit to issue an alarm and controls the inverter to adjust the rotational speed of the rotating shaft member.

10. The rotating machine according to any one of claims 1 to 3, wherein the predetermined number of times is multiple times.

11. The control device is a rotating machine according to any one of claims 1 to 3, wherein the control device has a cloud communication function.

12. The rotating shaft member of the motor, A bearing that rotatably supports the aforementioned rotating shaft member, A first parameter acquisition unit acquires the electrical state value between the rotating shaft member and the ground portion as a first parameter, A second parameter acquisition unit that acquires the impedance related to the bearing as a second parameter, A control method for a rotating machine comprising, A control method for a rotating machine, comprising: determining that the first parameter is in an abnormal state and outputting an electrical signal when the first parameter exceeds a first threshold a predetermined number of times or when the rate of change of the first parameter exceeds a reference value; and determining that the second parameter is in an abnormal state and outputting an electrical signal when the second parameter is below a second threshold, provided that the first parameter is not in an abnormal state.

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