Abstract:
A proposed implementation of this present subject matter utilizes a data collection and processing unit and sensors to monitor one or more conditions which can cause damage to a pump. These conditions include differential pressure across the pump, pump flow rate, and the pump rotational speed (RPM). Pump operating curves are analyzed to develop equations indicative of minimum and maximum allowable head for efficient operation within mechanical operation limits of the pump. The equations are used to set a processor for analyzing data inputs. The processor utilizes sensor inputs from the pump, including input and output pressure differential, flow, and pump speed. These values are compared to stored data or may be inserted into an equation to provide a calculated parameter indicative of operation in or out of pump operating limits. Responsive circuits inform users of alarm conditions.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
       [0001]    This application claims priority from provisional application Ser. No. 61/516,280, entitled “Fast-Response Pump Monitoring and In-Situ Pump Data Recording System,” filed on Apr. 6, 2011. The contents of this provisional application are fully incorporated herein by reference. 
     
    
     BACKGROUND 
       [0002]    1. Field 
         [0003]    The present matter relates to wireless communications and pump monitoring, and more particularly to monitoring of pump operations. 
         [0004]    2. Background 
         [0005]    The present subject matter is discussed in the context of an end suction centrifugal pump, although it is not so limited. One significant application is irrigation of fields. A pump is placed adjacent to a water source such as an irrigation canal. The pump is generally included in a pumping system which includes a framework supporting the unit and a driver such as a diesel engine for rotating the pump&#39;s impeller. The pumping station may be placed on skids. The pumping station is large and expensive. It may not be used year-round. Therefore, many users rent pump systems rather than buy them. 
         [0006]    A number of operating curves may be used to describe pump performance. Curves take into account such parameters as power required to operate the pump, rotational speed, and the amount of water to be pumped. Within certain parameter value ranges, the pump will operate most efficiently. Outside of selected limits, the pump may be damaged, perhaps irreparably. 
         [0007]    The user who rents a pumping system commonly has little knowledge of pump operating characteristics and pump maintenance. It is unlikely that such a user will have significant operating experience with the pump. The user may not know how to take action to avoid operating within parameter value ranges which will damage the pump when this condition occurs. The pump owner is generally unable to document circumstances which will demonstrate responsibility on the part of the user. In any case the pump owner would prefer to avoid damage. 
         [0008]    The potential for large financial loss to the pump owner is present. It is also significant that the pump owner will have significant downtime when the pump is damaged. During downtime, the pump cannot operate to generate revenue to cover the expenses associated with ownership. The many different expenses include depreciation and cost of deploying the pump. 
         [0009]    The conventional pump control unit does not respond proactively in response to current operating conditions. Generally, operations are not diagnosed to predict imminent pump failure due to select conditions. 
         [0010]    In one form of conventional control, pump parameters are measured and then transmitted to a control facility at a remote location. Prior art systems may transmit locally generated, condition-responsive signals to remote locations for processing at a “back end” server. Control room personnel and control room processors can process data and send commands to provide changes and corrections of operational parameters. 
         [0011]    Communications link service can be interrupted for any of a number of reasons. If a communications link is interrupted, the control systems at the back end are “blind” for the period of the interruption. During this period, conditions may occur which will damage a pump. Because the pump operator is not in a position to know the current values of parameters, a response cannot be made in view of current conditions. Consequently, the control server and control personnel are incapable of preventing damage to very expensive machinery. 
       SUMMARY 
       [0012]    Briefly stated, in accordance with the present subject matter, an apparatus and method are provided which monitor pump operations and are capable of providing proactive controls at a pump location. Processing of condition-responsive signals is done locally, i.e., at a pump location. A local connection to the signals is provided. A wide area network link is not a necessity. Alarms may be generated locally in response to local conditions. In the event of a communications link interruption, the local system can store information for transmission to a control server when the communications link is restored. 
         [0013]    A proposed implementation of this present subject matter utilizes a data collection and processing unit and sensors to monitor one or more conditions which can cause damage to a pump. These conditions include differential pressure across the pump, pump flow rate, and the pump rotational speed (RPM). Pump operating curves are analyzed to develop equations indicative of minimum and maximum allowable head for efficient operation within mechanical operation limits of the pump. The equations are used to set a processor for analyzing data inputs. The processor utilizes sensor inputs from the pump, including input and output pressure differential, flow, and pump speed. These values are compared to stored data or may be inserted into an equation to provide a calculated parameter indicative of operation in or out of pump operating limits. 
         [0014]    The local system can also decide how much information to send to a remote server. For example, if a pump is operating steadily, the system could transmit a “non-alarm” signal periodically to the remote server. When conditions approach or exceed operation limits, the system could transmit more frequently. This reduction in data transmission provides for decreased expense for required bandwidth and simplifies data processing requirements at the server. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0015]      FIG. 1  is a block diagram of a system embodying the present subject matter; 
           [0016]      FIG. 2  is a typical pump operating curve; 
           [0017]      FIG. 3  is a depiction of a curve fitting technique for simplifying alarm detection; 
           [0018]      FIG. 4  is an illustration of a system in accordance with the present subject matter including an isometric view of mechanical components and a block diagrammatic representation of electronics components; 
           [0019]      FIG. 5  is an enlarged isometric view of the pumping module; 
           [0020]      FIG. 6  is a flowchart of the processing that occurs within the data collection and processing unit; and 
           [0021]      FIG. 7  is a waveform chart illustrating transmission of data from the pump system to a remote system. 
       
    
    
     DETAILED DESCRIPTION 
       [0022]      FIG. 1  is a block diagram illustrating a field unit  1  embodying the present subject matter. By way of example, the present embodiment is designed for agricultural and environmental applications. However, the system is not limited to any particular application. This field unit  1  comprises an electronics module  2  and a pumping module  4 . The electronics module  2  comprises a control module  6  and a communications module  8 . The communications module  8  may communicate with either or both of a local base station  20  and a remote base station  30 . Signals may be transmitted to the remote base station  30 , for example, by satellite dish and/or cell phone link. Signals may also be collected by a satellite dish or cellular tower and provide data to the remote base station  30  via the Internet. 
         [0023]    The pumping module  4  pumps water from a source, such as an irrigation canal  14 , to a destination, which could be, for example, a crop field  16 . The pumping module  4  operates in accordance with operating curves further described with respect to  FIGS. 2 and 3 . The control module  6  utilizes transducers, described further with respect to  FIG. 4 , to monitor operating parameters of the pumping module  4  which are used to characterize the nature of operation. The control module  6  may also include memory for recording data. Additionally, the control module  6  may comprise control circuitry to respond to received signals and produce control signals to command operations of the electronics module  2 . 
         [0024]    The communications module  8  transmits information to either or both of the local base station  20  and the remote base station  30 . The base stations  20  and  30  may be located virtually anywhere. In one preferred embodiment, the local base station  20  is located at an office adjacent the crop field  16 . The field unit  1  data is then accessible at one local physical location even though the field unit  1  may be moved to any of a number of locations within the a crop field  16 . The remote base station  30  may be located at a main office of a company that leases field units  1  to growers. The base stations  20  and  30  are informed of operating conditions. 
         [0025]    Data produced by the electronics module  2  may be processed in any of a number of ways, for example, as discussed with respect to  FIG. 4 . In one embodiment, the electronics module  2  records operating data, but does not control operations. The pump owner may have a record of pump operations. In this manner, the pump owner can document if damage was due to negligent operation by the pump operator. 
         [0026]    Various options exist for processing data and using it to control operation. The electronics module  2  may include processing circuitry for local, automatic control of operation in response to condition responsive signals. In another embodiment, information may be processed at the base station  20 , and control signals may be sent to the local control module  6  in the electronics module  2 . Information may be transmitted to the remote base station  30  either directly or via the local base station  20 . In another alternative the electronics module  2  may be interact with instructions transmitted directly from the remote base station  30 . Further alternatively, instructions may be provided from the remote base station  30  to personnel at the local base station  20  to make adjustments locally. 
         [0027]    Communication with the remote base station  30  may provide for interactive control. However, if a communications link with the remote base station  30  is lost, then the remote base station  30  is without input information describing operation of the pumping module  4 . The field unit  1  can operate by itself to prevent and/or record “out-of-limits” operation so that damage can be avoided even if there is no communication with the remote base station  30 . 
         [0028]      FIG. 2  is a depiction of a typical pump operating curve. The abscissa is pump speed in rpm, and the ordinate is maximum head in meters for a selected pump. In a preferred embodiment, the pumping module  4  comprises a centrifugal pump  44  ( FIG. 4 ). Fluid enters the pump through the eye of an impeller which rotates at high speed. The fluid is accelerated radially outwardly. A vacuum is created at the impeller&#39;s eye that continuously draws more fluid into the pump and discharges the fluid to create head. A pump&#39;s head indicates a difference between input pressure and output pressure. Head is the vertical lift in height, generally measured in feet or meters of water, to which the pressure generated by the pump can lift water. Head is measured vertically from a centerline of the pump to the height of a discharge outlet. This is also known as static head. Dynamic head is the sum of static head and friction in the pump&#39;s suction. Dynamic head is a value used in horsepower calculations for pump operation. 
         [0029]      FIG. 2  is a nominal operating curve for a selected pump. In the present illustration, an XH 150 centrifugal pump is used. The XH-150 pump is an end suction centrifugal pump with an automatic priming system. The priming system utilizes a standard air compressor, which feeds a pneumatic ejector mounted above the air/water separation tank. With this device, suction lifts up to 28 ft. (8.5 m) can be achieved. The pump uses an impeller with a five blade, stainless steel closed construction design, with an eye diameter of 6.85″ (174 mm). The impeller is mounted on a 431 stainless steel shaft fitted to a cast iron bearing bracket; which also provides concentric location for the pump volute. A number of manufacturers make an XH 150 pump. One example is the XH-150 pump available from Western Oil Services Company under the trademark PowerPrime. 
         [0030]    Each curve in  FIG. 2  illustrates head versus flow rate for one value of rotational speed of the impeller of the pump  44 . A centrifugal pump operates at the point on its performance curve where its head matches the resistance in the pipeline. The point on the curve where the flow and head match the application&#39;s requirement is known as the duty point. A duty point can be established by varying such parameters as pump speed or impeller vane length. 
         [0031]    Various conditions, e.g., change of height of water in the irrigation canal  16  ( FIG. 1 ), can cause an operating point to move to the right as seen in  FIG. 2 . This may be characterized as a decrease in head and an increase in pump speed. When head versus pump speed decreases below a given level, cavitation results. Cavitation is the collapse of bubbles that are formed in the eye of the impeller due to low pressure. The implosion of the bubbles on the inside of the vanes creates pitting and erosion that damages the impeller. In order to avoid allowing operation which will damage the pump  44 , limits need to be determined for head versus pump speed. 
         [0032]      FIG. 3  is a depiction of a curve fitting technique for simplifying alarm detection. The curve fitting technique utilizes the relationship of head to rotational pump speed. The head versus speed relationship is a quadratic function with constants being inherent to particular pumps and applications. The lower curve of  FIG. 3 , Minimum Head, represents pairs of values defining a ratio below which cavitation will occur. The higher curve of  FIG. 3 , Maximum Head, represents pairs of values defining a ratio above which pump overload will occur. Measurement of operating parameters can be made, and the values are correlated to the points on  FIGS. 2 and 3  at which a pump  44  operates. Consequently, values can be determined which are indicative of “out-of-limits,” or “alarm condition” operation. 
         [0033]    The advantages of the present subject matter include, without limitation, the ability to detect improper pump operations automatically, and to provide both local and remote alarm indications when the improper operation occurs. 
         [0034]      FIGS. 4 and 5  taken together illustrate one form of the field unit  1  in greater detail.  FIG. 4  is a block diagram of an electronics module  2  according to the present subject matter and an isometric view of the pumping module  4 .  FIG. 5  is an enlarged isometric view of the pumping module  4 . 
         [0035]    The field unit  1  may comprise a skid  40  on which components are mounted. The skid  40  facilitates transporting the field unit  1  into a location adjacent the first location  14  ( FIG. 1 ). A pump driver  42  provides motive power to the pump  44 . In the present embodiment, the pump driver  42  is a diesel engine. The pump driver  42  may be operatively coupled to a motor controller  47  ( FIG. 5 ). Other prime movers may be utilized. One alternative is an electric motor. However, a diesel engine is generally better suited for high volume pumping applications of heavy fluid such as water. The pump  44  is, in one preferred form, a centrifugal pump  44  having a suction inlet  46  and an outlet  48 . 
         [0036]    Transducers, more particularly described below, provide inputs to the control module  6  which are indicative of various values that describe operation of the pump  44  comprise inputs to the control module  6 . The set of transducers in the field unit  1  is referred to collectively as the sensors  62 . The sensors  62  do not define a closed set. The sensors  62  may be included in a sensor module  60 . Transducers in addition to those described below may be provided. The inputs may be either analog or digital. 
         [0037]    The sensors  62  may include a suction pressure sensor  50 , which senses input pressure at the inlet  46 . A discharge pressure sensor  52  senses pressure at the outlet  48 . A flowmeter  54  measures volume of liquid pumped. In irrigation applications, the liquid will be water. A pump speed indicator  58  monitors speed of the pump  44 , generally in rpm. The sensor module  60  communicates with the control module  6  to receive and process signals from the sensors  50 ,  52 ,  54 , and  58 . The sensor module  60  may or may not be located within the control module  6 . 
         [0038]    It is not essential to have a discrete interface and control module  6  at the pumping module  4 . The control module  6  is used as a device in the description to indicate that data is coupled from sensors at the pump  44  for processing. This may be done in a number of ways. In one implementation, the suction pressure sensor  50 , the discharge pressure sensor  52 , and the flowmeter  54  are each coupled by a respective wire pair to provide DC signals to the control module  6 . The sensor module  60  may incorporate an analog to digital converter to provide a digital signal to the bus  70 . In one embodiment, the pump speed indicator  58  is coupled to the control module  6  via the sensor module  60  by a CAN (Controller Area Network) bus  110 . The CAN bus  110  is designed to a standard to allow microcontrollers and devices to communicate with each other within a vehicle without a host computer. 
         [0039]    The electronics module  2  may be enclosed in an enclosure  80  ( FIG. 5 ) such as an NEMA 4X enclosure  80 . A solar panel  82  may be provided to allow completely untethered operation. A satellite or cellular whip antenna  84  and a GPS antenna  86  may be coupled to the communications module  8  for communication with the base stations  20  and  30 . 
         [0040]    The sensors, the control module  6 , and the communications module  8  communicate via a bus  70 . The control module  6  comprises a processor  78  and a memory  74 . The memory  74  is preferably a non-volatile memory. The processor  78  receives signals via the data bus  70  and processes condition responsive signals as described above with respect to  FIGS. 2 and 3 . A condition-responsive circuit  88  is provided to process data from the sensor module  62 . Signals produced include alarm signals and control signals. There are two states for a signal indicative of an alarm. One state is an out-of-limit condition. The other state may be called “normal,” “in-limits,” or the absence of an out-o-limit condition. The motor controller  47  is coupled to the condition-responsive circuit  88 . The condition-responsive circuit  88  provides commands to the motor controller  47 . The commands may command the motor controller  47  to shut down the pump driver  42  or to adjust operating parameters. The condition-responsive circuit  88  is provided with criteria and coupled to select manual local control or control transmitted from a remote location such as the remote base station  30 . For example, the condition-responsive circuit  88  may command local control when communications with the remote base station  30  are interrupted. 
         [0041]    The memory  74  may be provided with and may store fixed physical constants, instruction sets, pump limits, curve fit equations, and settable levels to which to compare unprocessed or processed sensor outputs. If the processed output is outside the pump operating limits, an alarm will be issued and data saved to the memory  74  until such time that the alarm has cleared. An alarm message will be sent to a field wireless modem  72  for transmission to remote locations. Optionally, the alarm condition can be placed on the electronic bus  70  of the motor controller  47 , if one is included in a particular embodiment, for display and control. Alarm messages may continue at a configurable interval until the alarm clears. 
         [0042]    The communications module  8  comprises an I/O (input/output) card  100  that provides an interface to the bus  70 . The I/O card  100  also is coupled to a communications link  98  in the communications module  8 . The communications link  98  is preferably a full duplex communicator. The communications link  98  can take one or more of the following forms: satellite radio, a cellular module, a local area network modem, or other communication means. In another form, the communications link  98  can provide one-way communications from the communications module  8 . 
         [0043]    The field unit  1  may be constructed in a modular manner so that it can be assembled and mounted easily, and then locally switched on to begin data collection and data delivery. The remainder of the operation is intended to be completely unattended. Basic operating parameters can be configured such as data delivery, sleep intervals, sensor configuration, sensor read interval, alarm levels, and battery voltage set points. The unit is fully duplex for remote management and can be made at reasonable cost to include enough memory to log over one years&#39; worth of continual measurements. 
         [0044]    The processor  78  compares selected values from the sensor module  60  to threshold levels from the memory  74  and supplies inputs to the condition-responsive circuit  88 . The condition-responsive circuit  88  operates devices to indicate selected conditions. In the present illustration, an audible alarm  93  and a lamp  95  are used to indicate alarm conditions. Many other devices could be provided. The lamp  95  could also be operative to provide a first or a second color to indicate normal operation or an alarm condition respectively. The lamp  95  could comprise, for example, a plurality of light emitting diodes (LEDs) of first and second, or more, colors. 
         [0045]    In a preferred form, the processor  78  produces control signals which are provided to the interface and control module  6  for adjusting values of operating parameters of the pump  44 . 
         [0046]    In  FIG. 1  as well as in  FIGS. 4 and 5 , components are located to perform their functions. The description of a component as being in a particular module is for convenience, and is not limiting as to its physical location in the field unit  1 . 
         [0047]    The local base station  20  may conveniently comprise a server  130  and a personal computer  132 . The server  130  may, for example, present data to the personal computer  132  as an Internet web page. The local base station  20  receives alarms. Owner personnel at the local base station  20  may use other communications means to contact user personnel. Additionally, the local base station  20  may provide operator generated or computer generated control signals for transmission to the control module  6 . The control signals may be utilized to vary operating parameters of the pump  44  or to shut it off. It will generally be preferable to produce control signals at the control module  6 . In many applications, the local base station  20  will be remote from the electronics module  2 . However, this is not necessary. 
         [0048]    The remote base station  30  includes a server  140  to interact with an interface device  142 . The interface device  142  couples the remote base station  30  to the bus  70 . 
         [0049]    With the alarm data saved to the memory  74 , a historical record of improper operations is maintained that can be used to identify causes of pump failure and damage. A memory module may be included in the memory  74  as a separate location from which historical data may be access. Automatic alarm notifications allow personnel to take corrective actions when the pump is being operated outside of limits, preventing pump failure and/or damage. The curve fitting of the pump operating curve reduces the memory and processing required to detect an out-of-band condition, and provides a technique for determining improper operations at any pump speed. The system is capable of switching between curves automatically as defined by the application program and configuration parameters. 
         [0050]      FIG. 6  is a flow chart demonstrating the operation of the pump monitoring and alarm algorithm that occurs within the electronics module  2 . Operation begins at block  200  with power-on. Configuration parameters are read  202 . The sensor inputs required for the pump protection algorithm are pump differential pressure, flow, and pump speed. These values are read  204 . The sensor inputs values are then compared to a tabular or equation form of the pump operating limits  206 , and if outside the limits  208 , a remote and/or local alarm is issued  210 ,  212 . The alarm data is saved to memory  214 . The process continues at a configurable interval when the sensor inputs are read again  216 . If the pump operating limits continue to be violated  218 , further alarm messages are sent  220  at a configurable interval. When the pump begins operating within its limits, the alarm condition is turned off  222  and the process of reading the sensor inputs  204  and comparing them to the alarm limits  206  continues indefinitely. 
         [0051]      FIG. 7  is a waveform chart of signals produced by the condition responsive circuit  88 . In  FIG. 7 , the abscissa is time, and the ordinate in signal height in arbitrary units. Signals representing the values of operating parameters go to the condition-responsive circuit  88 . The signals may be translated to the communications module  8 . However, a comparison may be made so that when the system is operating nominally, a non-alarm signal  310  is produced periodically. The bandwidth of a non-alarm signal is narrower than the bandwidth required for parameter data. Full data can be sent to the remote database  30 . When an alarm condition occurs, packets  320  are produced having field  324  in the packet architecture. These fields provide specific operation data. Other forms of signals than digital packets may be generated and utilized. 
         [0052]    While the foregoing written description of the present subject matter enables one of ordinary skill to make and use what is considered presently to be the best mode thereof, those of ordinary skill will understand and appreciate the existence of variations, combinations, and equivalents of the specific embodiment, method, and examples herein. The present subject matter should therefore not be limited by the above described embodiment, method, and examples, but by all embodiments and methods within the scope and spirit of the present subject matter.