Patent Publication Number: US-2022221375-A1

Title: A Method and a Condition Monitoring Device for Monitoring a Rotating Equipment

Description:
TECHNICAL FIELD 
     The present disclosure relates in general to condition monitoring of rotating equipment. More particularly, the present disclosure relates to a method and a condition monitoring device for monitoring a rotating equipment. 
     BACKGROUND 
     Rotating equipment such as, motors, generators, pumps and the like are highly important in industrial applications. The rotating equipment are affected by environmental, mechanical, and other issues, most of which can be rectified. Due to these issues, condition monitoring of the rotating equipment has become an important factor in industries. The condition monitoring of rotating equipment is a process of monitoring parameters of a particular condition in the rotating equipment (such as, vibration, temperature etc.), in order to identify a significant change which is indicative of a developing fault. The use of condition monitoring allows maintenance to be scheduled, or other actions to be taken to prevent consequential damages and avoid its consequences. 
     Nowadays, in almost every applications, rotating equipment such as, motors are used. The motors are differentiated based on multiple factors, one being an operating time of the motors. The operating time of motors differ based on duty cycle. For instance, some of the motors run continuously, while some motors may run in a time period. 
     Multiple parameters of the motors are monitored during the condition monitoring. One of the parameters being the start and stop status of the motors. Typically, for the motors which runs continuously, determination of exact start and stop time might be of less importance. Currently, the running condition of the motor is determined for hourly basis. Thus, the start and stop events for the motors is recorded with a resolution of approximately an hour. This resolution may be well suited for continuous duty motors. However, for the motors having intermittent duty cycle, it may be required to monitor the running condition more frequently. The intermittent duty cycle is cycle of operation occurring on an interval basis. Thus, detecting the start and stop events of the rotating equipment with a lesser resolution period is desired. 
     SUMMARY 
     An aspect of the present disclosure relates to a method of monitoring a rotating equipment using a condition monitoring device. The condition monitoring device comprises a plurality of sensors for measuring one or more parameters associated with the rotating equipment and a processor for processing data measured using the plurality of sensors. The method is performed at every predetermined time period and after every predetermined time interval. 
     The method comprises detecting presence of vibration in the rotating equipment based on a signal associated with vibration in the rotating equipment. The signal is measured with one or more sensors of the plurality of sensors and corresponds to a measurement location of the one or more sensors based on a placement of the condition monitoring device relative to the rotating equipment. Upon detecting the presence of vibration in the rotating equipment, the method comprises acquiring a predefined number of samples associated with the vibration at a first frequency. The predetermined number of samples are acquired using the one or more sensors. The predefined number of the samples are utilised for calculating a Root Mean Square (RMS) value of vibration. Further, the method includes comparing the calculated RMS value of vibration with a reference value for detecting an operating status of the rotating equipment. The reference value is calculated from data measured by the plurality of sensors at beginning of the predetermined time period. 
     Particularly, the reference value is calculated based on vibration data measured at the beginning of each predetermined time period. In an embodiment, the rotating equipment receives power at a variable frequency which is used in calculation of the reference value at the beginning of each predetermined time period. In an embodiment, the operating status of the rotating equipment comprises information on one or more start of the rotating equipment and one or more stop of the rotating equipment at the plurality of predetermined time interval. In an embodiment, if the RMS value is greater than the reference value, the operating status of the rotating equipment is detected as start. Further, the method includes storing the operating status of the rotating equipment detected for every predetermined time interval. Thereafter, the method comprises processing information stored for each of the predetermined time intervals in the predetermined time period, to assess a condition of the rotating equipment. In an embodiment, the condition of the rotating equipment is determined based on the processed information associated with the plurality of predetermined time interval and the processed information associated with the predetermined time period. 
     In an implementation, the present disclosure may relate to a condition monitoring device for monitoring a rotating equipment. The condition monitoring device comprises a plurality of sensors configured to measure data associated with the rotating equipment. At every predetermined time interval, one or more sensor of the plurality of sensors is configured to generate a signal associated with vibration at a measurement location relative to the rotating equipment and acquire a predefined number of samples associated with the vibration at a first frequency. Further, the condition monitoring device comprises a network interface configured to communicate with a server and a processor. The processor performs one or more operations in the predetermined time period, after every predetermined time interval. Particularly, the processor detects presence of vibration in the rotating equipment based on the signal generated by the one or more sensors. Upon detecting the vibration based on the signal, the processor calculates a Root Mean Square (RMS) value of vibration using the predefined number of samples received from the one or more sensors. Further, the processor compares the calculated RMS value with a reference value for detecting an operating status of the rotating equipment. The reference value is calculated based on the data measured by the plurality of sensors at beginning of the predetermined time period. The operating status detected for every predetermined time interval is stored in a memory. The memory is communicatively coupled to the processor. Thereafter, the processor processes information stored for every predetermined time intervals in the predetermined time period, to assess a condition of the rotating equipment. 
     The processor may optionally comprise providing data measured by each of the plurality of sensors to the server using the network interface. Further, receiving the information for assessing the condition of the rotating equipment. The information is processed at the server based on the provided data. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The novel features and characteristic of the disclosure are set forth in the appended claims. The disclosure itself, however, as well as a preferred mode of use, further objectives and advantages thereof, will best be understood by reference to the following detailed description of an illustrative embodiment when read in conjunction with the accompanying figures. One or more embodiments are now described, by way of example only, with reference to the accompanying figures wherein like reference numerals represent like elements and in which: 
         FIG. 1  is illustrative of a motor schematic including a condition monitoring device in accordance with an embodiment of the present disclosure; 
         FIG. 2  shows a functional block diagram of the condition monitoring device, in accordance with an embodiment of the present disclosure; 
         FIG. 3  illustrates an exemplary embodiment for a condition monitoring device communicating with a server for monitoring a rotating equipment, in accordance with an embodiment of the present disclosure; 
         FIG. 4  shows a flowchart of a method for monitoring a rotating equipment in accordance with an embodiment of the present disclosure; and 
         FIG. 5  illustrates an exemplary graph representing operating status of a rotating equipment device in accordance with an embodiment of the present disclosure. 
     
    
    
     DETAILED DESCRIPTION 
     Embodiments of the present disclosure relate to a method and a condition monitoring device for monitoring a rotating equipment. In an embodiment, the rotating equipment may be one of motors, generators, pumps and the like, used in an industrial environment. The method is performed using a condition monitoring device associated with the rotating equipment. The condition monitoring device may be affixed to the rotating equipment in order to monitor the rotating equipment. Particularly, the condition monitoring device may detect an operating status of the rotating equipment based on the monitoring in order to access a condition of the rotating equipment. 
     Reference is now made to  FIG. 1  showing a schematic diagram of a motor  100 . The motor  100  may be any motor operating with an intermittent duty cycle. In an embodiment, the intermittent duty cycle may be defined as an operation period which occurs on an interval basis, for example, duty cycle of one hour. As shown in  FIG. 1 , the motor  100  is affixed with a condition monitoring device  101 . The condition monitoring device  101  may monitor the motor  100  to access a condition of the motor  100 . Particularly, the condition monitoring device  101  may monitor the motor  100  for every predetermined time period for detecting an operating status of the motor  100 . For instance, the predetermined time period may be one hour. The monitoring may be performed after every predetermined time interval in the predetermined time period. For example, the predetermined time interval may be 2.5 minutes. Thus, in this case, the monitoring may be performed after every 2.5 minutes in the one-hour time period. The monitoring and processing data at the rotating equipment in predetermined time interval may save memory space and lead to power conservation in the condition monitoring device  101 . The operating status of the motor  100  may include information on start of the motor  100  and stop of the  100  at the predetermined time interval. The operating status may be detected for a plurality of predetermined time interval. For example, the operating status may include information if the motor  100  is at start position or at stop position at every predetermined time interval. The information associated with the operating status may be processed to access a condition of the motor  100 . 
       FIG. 2  shows a functional block diagram of the condition monitoring device, in accordance with an embodiment of the present disclosure. 
     A simplified representation of a condition monitoring device  101  is shown in  FIG. 2 . The condition monitoring device  101  comprises a housing body  103  capable of being affixed to a body or shell or frame of the rotating equipment such as, the motor  100  (as shown in  FIG. 1 ). The housing body  103  houses a plurality of sensors including, but not limited to, a vibration sensor  204 , a magnetic field sensor  205  and other sensors  206 . The vibration sensor  204 , the magnetic field sensor  205  are collectively represented as one or more sensors throughout the present disclosure. The one or more sensors record and transmit measured signal. The one or more sensors may perform the measurement according to the placement of the condition monitoring device  101  relative to the rotating equipment. 
     Further, the condition monitoring device  101  includes a memory  201  for storing data. The data may include data measured by the one or more sensors while monitoring the rotating equipment. The data may include a reference value which is used for detecting the operating status of the rotating equipment. Further, the data includes the operating status calculated for the rotating equipment for the plurality of predetermined time interval. 
     In an embodiment, the vibration sensor  204  such as an accelerometer may be used to measure vibrations in the rotating equipment. The vibration sensor  204  is used for measuring the vibration of the rotating equipment after every predetermined time interval, which then is used by the condition monitoring device  101  for detecting the operating status of the rotating equipment. The vibration sensor  204 , i.e., for example, the accelerometer is configured to perform or measure vibration data after every predetermined time interval. For example, the accelerometer may be in “wake up on vibration mode”. The vibration sensor  204  may be associated with a timer which may be configured for measuring the data after every predetermined time interval. 
     In an embodiment, the magnetic field sensor  205  or a magnetometer may be used to measure the magnetic flux around the rotating equipment, such as the motor  100 . The magnetic field sensor  205  is a transducer which converts magnetic field strength to electrical signals. The magnetic flux measured is used to calculate line frequency of the rotating equipment. At the beginning of each predetermined time period, data from the vibration sensor  204  and the magnetic field sensor  205  are measured for calculating the reference value of RMS value of vibration. 
     Additionally, the condition monitoring device  101  may include a network interface  203  configured for communication with an external entity. In one embodiment, the network interface  203  is capable of communicating over wireless media such as Bluetooth, Wireless HART, and the like. The network interface  203  may communicate with the external entity using an antenna  207  as shown in  FIG. 2 . In another embodiment, the network interface  203  may be configured to facilitate communication between the processor  202  and the external entity. The external entity may include a server and the like.  FIG. 3  illustrates an exemplary embodiment for a condition monitoring device communicating with a server for monitoring a rotating equipment, in accordance with an embodiment of the present disclosure. In an embodiment, as shown in  FIG. 3 , the condition monitoring device  101  associated with the rotating device, the motor  100 , is connected with a sever  301 . In such a scenario, according to relative placements, the one or more sensors may measure data and send the measurements to the processor  202 , which may communicate raw data through the network interface  203  to the server  301  for processing. The condition monitoring device  101  receives processed information from the server  301  for assessing the condition of the motor  100 . 
     Further, the condition monitoring device  101  also includes a processor  202  configured to receive measurements from the one or more sensors and detects the operating status of the rotating equipment. The processor  202  is configured to monitor and detect the operating status of the rotating equipment periodically at every predetermined time period. After every predetermined time interval in the predetermined time period, the processor  202  receives a signal associated with vibration from the vibration sensor  204  to detect a presence of vibration in the rotating equipment. 
     For example, vibration in the motor  100  may be detected by the vibration sensor  204  such as the accelerometer, which may signal the processor  202  for collecting data. The signal corresponds to a measurement location of the vibration sensor  204  based on the placement of the condition monitoring device  101  relative to the rotating equipment. In case the vibration is detected, the processor  202  acquires a predefined number of samples of vibration from the vibration sensor  204  at a first frequency. In an example, the predefined number of samples may be sixty-four samples and the first frequency may be two Kilohertz. The predefined number of samples of vibration is acquired for calculating the Root Mean Square (RMS) value of vibration for the rotating equipment. 
     A person skilled in the art would understand that any predefined number of samples may be acquired for determining the RMS value of vibration in the present invention. In an embodiment, the RMS value of the vibration is calculated by any known techniques. Further, the processor is configured to compare the RMS value of vibration with the reference value to detect the operating status of the rotating equipment at the predetermined time interval. In an embodiment, the processor  202  calculates the reference value at the beginning of the predetermined time period based on the data measured by the plurality of sensors. The rotating equipment is detected to be in start state, if the RMS value of vibration is determined to be greater than the reference value. Likewise, the rotating equipment is detected to be in stop state, if the RMS value of vibration is determined to be lesser than the reference value. The operating status detected for every predetermined time interval in the predetermined time period is processed in order to assess the condition of the rotating equipment. 
       FIG. 4  shows a flowchart of a method for monitoring a rotating equipment in accordance with an embodiment of the present disclosure. 
       FIG. 4  illustrates a flowchart of the method for monitoring the rotating equipment in accordance with an embodiment of the invention. The rotating equipment may be typically present in an industrial environment, for example, a process plant and the like. 
     The rotating equipment such as the motor  100  is associated with the condition monitoring device  101 . The condition monitoring device  101  is installed/affixed on the rotating equipment for monitoring. The condition monitoring device  101  detect the operating status of the rotating equipment at every predetermined time interval, which is used for assessing the condition of the rotating equipment. 
     At the beginning of every predetermined time period of the rotating equipment, such as the motor  100 , the condition monitoring device  101  determines the reference value of vibration based on the data measured by the plurality of sensors. In an embodiment, the rotating equipment receives power at a variable frequency which is used in calculation of the reference value. Accordingly, the reference value is updated at every predetermined time period. 
     The condition monitoring device  101  receives a number of samples, for example, 1024 samples, measured by the vibration sensor  204  at a predefined frequency, for example, 2 khz, to determine a kurtosis and velocity RMS. Measurements from the plurality of sensors may be used for calculating speed and the line frequency of the rotating equipment. In an embodiment, the speed and the line frequency of the rotating equipment can be determined using any known techniques. Further, the condition monitoring device  101  receive a number of samples measured by the magnetic field sensor  205  at a predefined frequency, for instance, 300 Hz, to determine a frequency spectrum. In one embodiment, the number of samples may be collected from a multi-axial magnetic field sensor. The RMS value measured is compared against a threshold value of vibration to detect if the rotating equipment is in start/stop state. Particularly, the rotating equipment is detected to be in start state, if the RMS value measured is greater than the threshold value of vibration. In case, the rotating equipment is detected to be in start state, the reference value is updated with the RMS value. The reference value is stored in the memory  201 . Subsequently, after the predetermined time interval, for example, after two and half minutes, the condition monitoring device  101  may receive the data from the one or more sensors. 
     At block  401 , the method includes detecting presence of the vibration in the rotating equipment based on the signal associated with vibration. In an embodiment, the vibration sensor  204  may wait for a specific time, for example say two seconds, for detecting the presence of the vibration. In case the vibration is not detected in the specific time, the condition monitoring device  101  may check if the rotating equipment is switched “ON” and perform the detection of the vibration a predefined number of times. The detection of the vibration is initiated after every predetermined time interval. In an embodiment, the condition monitoring device  101  may set a timer for every predetermined time interval for the one or more sensors. Specifically, the vibration sensor  204  is configured to measure the signal which corresponds to the measurement location of the vibration sensor based on the placement of the condition monitoring device  101  relative to the rotating equipment. In an embodiment, the measurement location is the location where the condition monitoring device  101  is mounted on the rotating equipment. More specifically, the location is the location of the one or more sensors within the housing body  103  of the condition monitoring device  101  when the condition monitoring device  101  is affixed on the rotating equipment. In an embodiment, the condition monitoring device  101  may be positioned differently for measurements. In an embodiment, if no vibration is detected in the rotating equipment, the condition monitoring device  101  detect the rotating equipment to be at stop state and the timer is set for next predetermined time interval. 
     At block  403 , once the presence of vibration is detected in the rotating equipment, the method includes acquiring the predefined number of samples associated with the vibration from the vibration sensor  204 . The predefined number of samples are acquired at the first frequency. In an example, the predefined number of samples may include sixty-four sample, one twenty-eight samples and the like. A person skilled in the art would understand that the number of samples may be configurable in the present disclosure. In an example, the first frequency may be two kilohertz. A person skilled in the art would understand that the first frequency for collecting the predefined number of samples may be based on the rotating equipment and configurable in the present disclosure. In an embodiment, the predefined number of samples associated with the vibration includes acceleration values of the rotating equipment during vibration. 
     At block  405 , the method includes calculating the RMS value of vibration based on the predefined number of samples. In an embodiment, the RMS value is defined as square root of the average of the squared values of waveform. In an embodiment, the RMS value of vibration may be calculated by any known existing techniques. 
     At block  407 , the method includes comparing the calculated RMS value of vibration with the reference value calculated for the predetermined time period. Particularly, the reference value for vibration may change over time, if the rotating equipment is operated at variable frequency. Thus, the reference value is calculated at each predetermined time period in order to improve accuracy of detection operating status of the rotating equipment. 
     Based on the comparison, the operating status of the rotating equipment is detected. In an embodiment, the operating status of the rotating equipment includes information on one or more start of the motor and one or more stop of the rotating equipment at each predetermined time interval of the predetermined time period. For instance, if the calculated RMS value is determined to be greater than the reference value, the operating status is detected to be as start state. In an embodiment, in order to determine the start of the rotating equipment, the amplitude of the RMS value may increase rapidly when the rotating equipment starts running such signal character is easy to be detected. The detection of start of the rotating equipment is implemented based on the reference value. When the amplitude of RMS value is larger than the reference value, it is considered that the rotating equipment is started. 
     In a similar manner, detection of stop of the rotating equipment can be performed. In an embodiment, the amplitude of the RMS value may decrease when the rotating equipment stops running same as in the case of the rotating equipment start, such signal character is obvious and easy to be detected. The detection of the rotating equipment stop is also implemented based on the reference value. When the amplitude of the RMS value is smaller than the reference value, it is considered that rotating equipment is stopped. 
     At block  409 , the method includes storing the operating status detected for the rotating equipment in the memory  201  for every predetermined time interval.  FIG. 5  illustrates an exemplary graph representing operating status of a rotating equipment device in accordance with an embodiment of the present disclosure.  FIG. 5  illustrates a graph of recording the operating status of a motor. In the present case, the graph is recorded for the motor with the predetermined time period of one hour and the predetermined time interval of two and half minutes. Thus, the operating status at every 2.5 minute is detected by the condition monitoring device  101  and stored as a bit information in a 24-bit format, where one bit corresponds to 2.5 minutes. Thus, if the motor is at start, the value of the bit will be “one” otherwise, it will be zero. Thus, the minimum interval with which the start/stop can be detected is 2.5 minutes. Therefore, at the end of every predetermined time interval, the bit values may be taken into account to determine the operating status. Consider, for example, if a user sets the predetermined time period as 30 minutes. In such case, 12 bits may be used to determine the operating status of the motor. Additionally, if the user sets the predetermined time period greater than 1 hour, then the 24 bits may be modified to fill the interval. For example, if the predetermined time period is 2 hours, then the 24 bits information may be recorded at every 5 minutes. In an embodiment, the condition monitoring device  101  may count the predetermined time interval by adding a counter at every predefined time, for example, ten seconds. For example, if the predetermined time period is one hour, the predetermined time interval of 2.5 minutes is counted by the counter which is reset once it reaches a value of fifteen. (15*10=150 sec=2.5 minutes). 
     At block  411 , the method includes processing the information stored for each of the predetermined time intervals in the predetermined time period to assess the condition of the rotating equipment. In an embodiment, information may also include one or more starts and one or more stops of the rotating equipment over the predetermined time period. Such information may include times of start/stop, number of starts/stops over a predetermined time period, loading related information and the like. The information is processed after every predetermined time period for assessing the condition of the rotating equipment. The condition of the rotating equipment is assessed based on the processed information associated with every predetermined time interval and the processed information associated with the predetermined time period. 
     In an embodiment, the processed information associated with every predetermined time interval and with the predetermined time period may be used by the server  301  to assess the condition of the rotating equipment. The condition may be associated with health status and also a condition requiring maintenance and/or other support. For example, the condition monitoring device  101  may have a simple life estimation model (e.g. empirical mathematical relations), which takes start/stop/change for estimating remnant life and predicting a condition requiring maintenance. An example of a simple life estimation model can empirically represent life as a curve relating count of number of starts specified for values of mean (average) load on the rotating equipment and the condition monitoring device  101  may use an mathematical expression relation representing the curve to estimate/predict a time or condition for maintenance based on the value of number of starts. Similarly, the condition monitoring device  101  can also incorporate mean time period between a start and stop signals of the rotating equipment along with the mean load values to determine a condition for maintenance. 
     Further, the method optionally includes receiving the information for assessing the condition of the rotating equipment, from the server  301  over the network interface  203  of the condition monitoring device  101 . Particularly, the server  301  in communication with the condition monitoring device  101 , receives the data measured by each of the plurality of sensors, which is processed to assess the condition of the rotating equipment. For example, the server  301  may have one or several models to process the data related to individual/several sensors of the condition monitoring device  101 . The processing of data from the plurality of sensors may be used to determine the condition of the rotating equipment. For instance, consider a case, where a motors at a specific site may experience failure after a certain number of starts/stops. An analysis module at the server  301  may use this information and correlate to detect the condition of the motor  100 . Further, the server  301  transmits the processed information to the condition monitoring device  101 . 
     Thus, a condition monitoring device  101  can assess conditions warranting service, maintenance or maintenance planning. This can be done based on information already available with the device during configuration, and information collected through its sensors/received from the server  301 . The condition monitoring device  101  can also send the raw data and/or processed data of the rotating equipment to the server  301 . At the server  301 , the information from the condition monitoring device  101  can also be gathered which may be utilized for various condition assessment and/or maintenance planning activities. 
     The present invention provides various advantages. The information associated with operating status such as, the start, the stop, can serve as input for one or several life estimation models at the condition monitoring device  101  (and/or life estimation model(s) at the server). The condition monitoring device  101  utilizes the information associated with start, stop for predicting a condition requiring maintenance and/or other support. A communication to trigger an action (e.g. schedule a maintenance etc.) may be sent (e.g. through communication by server, through communication by condition monitoring device etc.) based on the processed information. 
     This written description uses examples to describe the subject matter herein, including the best mode, and also to enable any person skilled in the art to make and use the subject matter. The patentable scope of the subject matter is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 
     
       
         
           
               
            
               
                   
               
               
                 REFERRAL NUMERALS 
               
            
           
           
               
               
            
               
                 Reference Number 
                 Description 
               
               
                   
               
               
                 100 
                 Motor 
               
               
                 101 
                 Condition monitoring device 
               
               
                 103 
                 Housing body 
               
               
                 201 
                 Memory 
               
               
                 202 
                 Processor 
               
               
                 203 
                 Network interface 
               
               
                 204 
                 Vibration sensor 
               
               
                 205 
                 Magnetic field sensor 
               
               
                 206 
                 Other sensors 
               
               
                 207 
                 Antenna 
               
               
                 301 
                 Server