TECHNICAL FIELD

[0001] The present subject matter relates, in general, to monitoring condition of electrical machines used in industrial systems, and in particular to changing an operational state of a condition monitoring device of an electrical machine.

BACKGROUND

[0002] An industrial system can be used to monitor and control one or more tasks performed in an industrial plant. Various industries, such as automobile industry, metallurgical industry, chemical industry, petrochemical industry, and power generation industry can utilize industrial systems to reduce human monitoring. One or more electrical machines may be used in the industrial systems. As an example, an electrical motor may be used in an industrial system to operate a pump to supply water to a boiler in a thermal power plant.

[0003] In industrial systems, the condition of the electrical machines may be monitored using condition monitoring devices. A condition monitoring device includes one or more sensors that measure one or more parameters related to the functioning of an electrical machine. These parameters may be shared with a portable device for further processing. To operate the various sensors, processors, and other electronic components of the condition monitoring device, a battery may be provided in the condition monitoring device as a power source.

[0004] The condition monitoring device may be mounted on the electrical machine at the manufacturing site. However, in order to conserve battery life during transit between the manufacturing site and the installation site, the circuitry inside the condition monitoring device might be put into sleep mode. In this mode, the circuit consumes approximately one third the power as compared to an active mode or power ON mode. Additionally, transit from manufacturing to installation site might involve air travel and regulatory requirements may mandate that the condition monitoring device should not be powered on during flights. In such a scenario, the sleep mode helps to reduce the chances of the condition monitoring device interfering with the aircraft's communication and navigation system. Further, even after commissioning, the operational state of the condition monitoring device may have to be switched between the sleep mode and active mode based on the operating conditions.

[0005] Conventionally, to switch the condition monitoring device between sleep mode and active mode, a physical switch/push button is provided on the condition monitoring device. By toggling the switch, the condition monitoring device is switched from the sleep mode to active mode. However, such switches and buttons are often subject to wear and tear and can malfunction at times. Moreover, such switches and button may get accidentally pushed during operation of the electrical machine and can cause disruption in condition monitoring. Further, such switches and buttons may lower the ingress protection of the condition monitoring device if not designed and assembled properly. BRIEF DESCRIPTION OF FIGURES

[0006] The features, aspects, and advantages of the present subject matter will be better understood with regard to the following description, and accompanying figures. The use of the same reference numbers in different figures indicates similar or identical features and components.

[0007] Fig. 1 illustrates an industrial system depicting a condition monitoring device for communicating a condition of an electrical machine with a portable device, in accordance with implementations of the present subject matter.

[0008] Fig. 2 illustrates a block diagram depicting a condition monitoring device, in accordance with implementations of the present subject matter. [0009] Fig. 3 illustrates a method for changing an operational state of a condition monitoring device of an electrical machine, in accordance with implementations of the present subject matter. DETAILED DESCRIPTION

[0010] The present subject matter relates to monitoring condition of an electrical machine in an industrial system. With the systems and methods of the present subject matter, an operational state of a condition monitoring device of an electrical machine can be changed based on data measured wirelessly by the condition monitoring device. This eliminates the need of any physical push button. It also helps to increase the security of the condition monitoring device when it is in the sleep mode during transit of the electrical machine.

[0011] In an implementation of the present subject matter, a condition monitoring device of an electrical machine is provided for communicating a condition of the electrical machine with a portable device. The condition monitoring device is attached to a body of the electrical machine. The condition monitoring device includes a plurality of sensors for measuring electrical and mechanical parameters of the electrical machine, and one or more processors to receive measurements from the plurality of sensors and determine the condition of the electrical machine based on the received measurements. The condition monitoring device also includes a network interface for communicating the condition of the electrical machine to the portable device.

[0012] Further, at least one sensor from the plurality of sensors is configured to be active irrespective of an operational state of the condition monitoring device. The at least one sensor is further configured to measure a mechanical parameter of the portable device and the one or more processors are configured to receive measurements of the mechanical parameter from the at least one sensor and cause one or more other sensors from the plurality of sensors to become active, based on the received measurements. Thus, the operational state of the condition monitoring device can be securely changed based on the measurement of a mechanical parameter of the portable device rather than using a physical push button or other such mechanism.

[0013] The above and other features, aspects, and advantages of the subject matter will be better explained with regard to the following description, appended claims, and accompanying figures.

[0014] Fig. 1 illustrates an industrial system 100 depicting a condition monitoring device 102 for communicating a condition of an electrical machine 106 with a portable device 104, in accordance with an implementation of the present subject matter.

[0015] The condition monitoring device 102 may be implemented as a computing device comprising a plurality of sensors, one or more processors, memories, network interfaces, and the like. The portable device 104 may be, for example, a smartphone, a personal digital assistant (PDA), a laptop, a tablet computer, or the like. The electrical machine 106 may be, for example, a motor, a generator, and the like.

[0016] In one implementation, the condition monitoring device 102 is attached to a body of the electrical machine 106 for communicating a condition of the electrical machine 106 with the portable device 104. Such a communication may be performed when the portable device 104 is in proximity to the electrical machine 106. The condition of the electrical machine 106 may include values of various parameters monitored and used for control of operations of the electrical machine, such as current, voltage, power, magnetic field, vibration, temperature, and acoustic noise about the electrical machine, among others.

[0017] Initially, the condition monitoring device 102 may be in a first operational state and may have to be switched to a second operational state. For example, prior to commissioning of the electrical machine 106, the operational state of the condition monitoring device 102 may be set to a low power state, also referred to as sleep mode. Placing the condition monitoring device 102 in the sleep mode helps in reducing battery consumption during transit and helps to meet regulatory requirements during air travel. To change the operational state of the condition monitoring device 102, a mechanical or electrical parameter may be measured by the condition monitoring device 102. In one example, to measure the mechanical or electrical parameter, at least one sensor of the condition monitoring device 102 may be in an always ON mode, i.e., it may be active irrespective of the operational state of the condition monitoring device 102.

[0018] The mechanical parameter may be, for example, a vibration signal or an acoustic signal generated by the portable device 104 when it is proximal to the condition monitoring device 102. In one example, the portable device 104 may generate a vibration signal or an acoustic signal that can be mapped to bits using the signal amplitude and frequency. For instance, a smartphone can produce a sequence of weak and strong vibrations which can then be mapped to bits, Morse code or other encoding schemes to produce a pattern, which is then measured by the at least one sensor. Information may be encoded into the mechanical parameter by using a plurality of well-known schemes. This is further illustrated below using a plurality of examples.

[0019] In one example, amplitude shift keying scheme is used by the portable device 104 for encoding information into the mechanical parameter. For instance, the mobile phone is using small amplitude vibrations at a given frequency to encode 0 and big amplitude vibrations to encode 1 . Similarly, in another example, frequency shift keying scheme may be used by the portable device 104 for encoding information into the mechanical parameter. For instance, a certain frequency may be mapped to 0 and another predetermined frequency may be mapped to 1 . It may be noted by a person skilled in the art that while two such encoding schemes have been illustrated, other techniques well known in the art may be used as well. [0020] Thus, techniques in existing communication protocols such as using specific structures for the messages (e.g., preamble, payload and Cyclic Redundancy Check) and encryption of the payload can be used for transmitting the data from the portable device 104 to the condition monitoring device 102.

[0021] In one example, the mechanical parameter measurement may also include embedded data that can be used by the condition monitoring device 102 to determine that its operational state is to be changed and accordingly the operational state can be changed to one or more active modes of operation. The embedded data in the mechanical parameter measurement may also include data for enhanced security, such as data for authentication of the portable device 104, authentication of the condition monitoring device 102, authentication of location of the portable device 104, authentication of the operator, and the like.

[0022] Implementations for changing an operational state of the condition monitoring device are further described with reference to Fig. 2, which illustrates an example block diagram of a condition monitoring device. While examples have been described with reference to change of operational state from a sleep mode to an active mode, it will be understood that the present subject matter can be used to change the operational state between any first state to any second state.

[0023] As shown in Fig. 2, an example condition monitoring device

102 includes an energy source 202, a plurality of sensors 204-1 , 204-2, 204- 3...204-n, collectively referred to as sensors 204, one or more processors 206, and a network interface 208.

[0024] In an example, the energy source 202 can include batteries.

In another example, the condition monitoring device 102 may be also powered by an external power supply. The sensors 204 can be used to measure various parameters, including electrical and mechanical parameters, of the electrical machine 106. For example, the sensors 204 may include one or more of a magnetic field sensor, a vibration sensor, an acoustic sensor, and a temperature sensor. The magnetic field sensor can measure a magnetic field. Similarly, the vibration sensor can measure vibration patterns; the acoustic sensor can measure acoustic signals; and the temperature sensor can measure a temperature in its vicinity. The parameters measured may be those of the electrical machine 106 and/or the portable device 104.

[0025] The one or more processors 206, hereinafter referred to as processors 206, are configured to receive one or more measurements of the parameters of the electrical machine 106 from the sensors 204. Based on the received measurements, the processors 206 can determine the condition of the electrical machine 106. Further, the network interface 208 is configured for communicating the condition of the electrical machine 106 to the portable device 104.

[0026] Initially, the condition monitoring device 102 may be in a first operational state. In one example, the first operational state may be a low power mode, such as sleep mode. To enable switching of the condition monitoring device 102 to a second operational state, a first sensor of the sensors 204, such as sensor 204-1 may be a low power sensor that may be always ON and active irrespective of the operational state of the condition monitoring device 102.

[0027] The sensor 204-1 may be, for example, a vibration sensor or an acoustic sensor and accordingly, the mechanical parameter measured by the sensor 204-1 may be a vibration pattern or an acoustic pattern. For example, the vibration sensor may be an accelerometer that is kept on and continuously monitors vibration patterns around the condition monitoring device 102. Upon measuring a vibration value above a predetermined threshold, the accelerometer is configured to send a signal comprising vibration pattern measurements to a processor of the processors 206. The processor can process the signal to determine whether the embedded data in the signal corresponds to a signal to switch the operational state of the condition monitoring device 102 and can change the operational state of the condition monitoring device 102 based on the processing. It will be understood that the signal corresponding to the mechanical parameter as mentioned herein can be generated by the portable device 104 by varying one or more of the amplitude, frequency, and duration of the mechanical parameter.

[0028] In one example, to ensure that operational state does not get changed due to noise or other accidental signals, the sensor 204-1 may be configured to send the signal to the processor when the measured mechanical parameter lies within a specified band of values, such as a band ranging from low g to high g {g being the acceleration due to gravity) or follows a specific pattern. Thus, the condition monitoring device 102 is not activated by any fall or accidental drop during transit.

[0029] In one example, to further ensure that the condition monitoring device 102 is not accidently activated from the sleep mode, the sensor 204- 1 may be configured to measure the mechanical parameter when the condition monitoring device 102 is in a predefined orientation, such as a horizontal orientation. The likelihood of the condition monitoring device 102 being in vertical orientation is high during transit and operation. However, it may be placed in a horizontal orientation prior to installation for activating it. The orientation may be detected by a second sensor of the sensors 204.

[0030] Thus, random vibrations or acoustic signals will not trigger the sensor 204-1 , for example, during transit. Moreover, measuring the mechanical parameter when the condition monitoring device 102 is in a predefined orientation helps in further saving energy as it takes less energy to check the orientation of a sensor then to measure a vibration pattern.

[0031] In one example, when the first sensor 204-1 is an accelerometer, the first sensor 204-1 may also act as the second sensor to detect the orientation of the condition monitoring device 102 and may begin measuring the mechanical parameter when the orientation is horizontal. In another example, when the first sensor 204-1 is an acoustic sensor, a second sensor 204-2, such as an accelerometer, may continuously monitor the orientation of the condition monitoring device 102 and may cause the first sensor 204-1 to measure acoustic signals upon the placement of the condition monitoring device 102 in a horizontal orientation.

[0032] To change the operational state, the portable device 104 is brought in proximity or in contact with the condition monitoring device 102 and is made to generate the mechanical parameter in a particular pattern. The particular pattern acts as embedded data for verifying whether the operational state of the condition monitoring device 102 is to be changed.

[0033] Upon detecting that the mechanical parameter value is above a predetermined threshold, the first sensor 204-1 measures the mechanical parameter, for example, for a pre-determined time period, and transmits the measured mechanical parameter to the processor 206. The processor 206 verifies the particular pattern in the measured mechanical parameter and based on the verification result wakes up one or more other processors and sensors, thereby activating other operating features.

[0034] In one example, the mechanical parameter measurement is also used to perform additional authentication steps, such as user authentication or location verification, before activating other operating features of the condition monitoring device 102. Accordingly, the processors 206 are configured to progressively increase the power consumed by the condition monitoring device 102, based on the authentication, for changing the operational state of the condition monitoring device to different active modes.

[0035] For example, the operational state of the condition monitoring device 102 may be changed from the sleep mode to a first active mode when the mechanical parameter is measured to be above the threshold value. Upon performing a first authentication step, the operational state may be changed to a second active mode where additional data is authenticated. The different active modes can correspond to different sampling frequencies at which the mechanical parameter is measured. Thus, as each authentication step is performed, a higher sampling frequency can be used for activating further sensors and operating features of the condition monitoring device 102, thereby progressively increasing the power consumption.

[0036] For extracting authentication data, the mechanical parameter signal may be first converted into a bit string at the condition monitoring device 102. A bit pattern corresponding to the data may be then identified in the bit string. The start of the bit pattern may be indicated using a predefined bit string called a preamble. This preamble comprises a certain sequence of bits that can be found in the bit string.

[0037] In an example, the preamble may be identified as a particular bit string, such as "001 001 001 ", which is stored in the condition monitoring device 102. After identifying the preamble, the condition monitoring device 102 can measure a pre-determined number of bits. The pre-determined number may also be stored in the condition monitoring device 102. For example, the pre-determined number may be 1000 bits. Hence, when the mechanical parameter is measured, the condition monitoring device 102 identifies the preamble "00 001 001 " in the bit string of the measured mechanical parameter to identify the start of the bit pattern. Thereafter, the condition monitoring device 102 detects the number of bits in the bit string after the preamble to identify the end of the bit pattern and decodes the data accordingly.

[0038] In an implementation, instead of the number of bits, the end of the bit pattern is identified based on a timer included in the condition monitoring device 102. Thus, the condition monitoring device 102 may identify the start of the bit pattern and continue to record the bit pattern for a pre-determined period of time or a particular number of pulses.

[0039] The data thus received through the mechanical parameter measurement can be used to perform authentication steps before the operational state of the condition monitoring device 102 is changed. In one example, authentication data may be stored on the at least one sensor, which is later compared to the data received through the mechanical parameter measurement.

[0040] Additionally, certificate, encryption keys and other type of security related information can be loaded inside the memory of the condition monitoring device 102 in order to enable additional security measures before the operational state of the condition monitoring device 102 is changed.

[0041] In one example, an authentication step may correspond to authenticating data encoded in the mechanical parameter signal, the data being from a QR code installed on the condition monitoring device 102. In the example, the QR code is scanned by the portable device 104. In another example, the mechanical parameter signal generated by the portable device 104 is encoded with authentication information, which may be in turn provided to the portable device 104 from a remote server available with the manufacturer of the condition monitoring device 102.

[0042] In an example, an authentication step may include authenticating the final destination of the condition monitoring device 102 based on data stored in the memory of the condition monitoring device 102 before shipment. During commissioning of the condition monitoring device 102, the GPS coordinates of the portable device 104 can be embedded or encoded into the mechanical parameter signal. Accordingly, the condition monitoring device 102 then compares these GPS coordinates with the final destination coordinates stored within its memory to authenticate the location. This can help to prevent the condition monitoring device 102 from being activated in a different location during transit.

[0043] In an example, the portable device 104 can be a mobile phone which can be unlocked by the operator's passcode or finger print. The passcode information is then encoded into the mechanical parameter signal and transmitted to the condition monitoring device 102. Accordingly, the condition monitoring device 102 utilizes this information to determine if the operator is authorized to wake up the condition monitoring device 102 from low power state for commissioning.

[0044] Thus, the condition monitoring device 102 can be in different operational states: an energy saving low power sleep mode with a slow sampling frequency and one or more active modes with higher sampling frequencies. The condition monitoring device 102 switches state depending on conditions of the measured mechanical parameter. For instance, for a condition monitoring device equipped by an accelerometer, the orientation of the device can be used to switch to a first active state for measuring the mechanical parameter at a low sampling frequency. The sleep mode can be thus used to detect mechanical parameter signals for state change with minimal power consumption. Once the mechanical parameter signals for state change has been received using the low sampling frequency, the condition monitoring device 102 changes its internal state and the frequency is increased to receive more data, e.g., data for changing the set of enabled features on the condition monitoring device 102 or new parameters for enabling certain features that may consume higher power.

[0045] In one example, at any step, if the authentication information from the measured mechanical parameter is not available or is not matched with the predetermined authentication information stored on the condition monitoring device 102, the condition monitoring device 102 returns to the sleep mode or to a previous operational state.

[0046] Fig. 3 illustrates an example method for changing an operational state of a condition monitoring device of an electrical machine, such as a condition monitoring device 102 of an electrical machine 106.

[0047] The order in which the method 300 is described is not intended to be construed as a limitation, and any number of the described method blocks may be combined in any order to implement the method 300 or an alternative method. Additionally, certain steps of method 300, such as step 302, may be eliminated without departing from the scope of the present subject matter. Furthermore, the method 300 may be implemented by processor(s) or computing device(s) through any suitable hardware, non- transitory machine-readable instructions, or a combination thereof. It may be understood that steps of the method 300 may be performed by programmed computing devices and may be executed based on instructions stored in a non-transitory computer readable medium. Although the method 300 may be implemented in a variety of systems, the method 300 is described in relation to the industrial system 100, for ease of explanation.

[0048] As depicted in step 302, an orientation of the condition monitoring device is determined. For example, an accelerometer of the condition monitoring device 102 may determine the orientation of the condition monitoring device 102. The accelerometer may be active irrespective of an operational state of the condition monitoring device 102 and can thus be used to activate the condition monitoring device 102 from a sleep mode or low power state.

[0049] At step 304, based on the orientation, a mechanical parameter of the condition monitoring device is measured. For example, only if the orientation is horizontal, then the mechanical parameter of the condition monitoring device 102 is measured. The mechanical parameter may be, for example, a vibration signal or an acoustic signal, and may be measured, for example, by the accelerometer or a different sensor.

[0050] At step 306, one or more of the portable device, a location of the portable device, and an operator of the portable device are authenticated based on authentication data embedded in the mechanical parameter measurements, before changing the operational state of the condition monitoring device. For example, the condition monitoring device 102 may identify embedded data in the measured mechanical parameter and may compare the data with pre-stored data stored in its memory to perform such authentication.

[0051] At step 308, one or more operating features of the condition monitoring device are activated, to change the operational state of the condition monitoring device. In one example, based on the authentication steps performed, the operational state of the condition monitoring device may be progressively changed from a sleep mode to one or more active modes. In one example, to activate the required operating features in the one or more active modes, one or more sensors may be activated. The one or more active modes correspond to different sampling frequencies at which the mechanical parameter is measured and thus also correspond to different amounts of power consumed.

[0052] Thus, the present subject matter allows transmission of data to a condition monitoring device for change of operational state without any physical port/ button in a secure manner. Since it is more difficult to intercept data sent as a mechanical parameter, such as vibrations, as compared to data broadcast over wireless communication protocols, the security is further enhanced. This is particularly useful while sending data such as encryption keys or commissioning information. Additionally, the security of the condition monitoring device 102 is further increased by enabling more authentication steps through secure data exchange using data transmitted through the mechanical parameter. Moreover, the power consumption is also controlled during the change of operational state and authentication by increasing the sampling frequency progressively based on the authentication steps performed.

[0053] Although the present subject matter has been described with reference to specific embodiments, this description is not meant to be construed in a limiting sense. Various modifications of the disclosed embodiments, as well as alternate embodiments of the subject matter, will become apparent to persons skilled in the art upon reference to the description of the subject matter.