JPS63639B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a pump operating state detection device for diagnosing or displaying whether a pump driven by a variable speed prime mover is operating in a normal operating range.

Conventionally, when controlling the discharge pressure or discharge flow rate of a pump driven by a prime mover such as a variable speed electric motor, the following method has been used to diagnose whether the pump is operating normally.

That is, FIG. 1 is a diagram showing a conventional example, in which 1a to 1c are variable speed electric motors and 2a to 2 are variable speed electric motors, respectively.
C is a pump provided corresponding to each of these variable speed motors 1a to 1c and driven by the variable speed motor; 3 is a pressure signal generator for detecting the pressure of the fluid sent by these pumps 2a to 2c; 4 is a flow rate signal generator that detects the flow rate of the fluid sent by the pumps 2a to 2c, 5 is an operating number detector that detects the number of pumps in operation, and 6 is a pressure that the detection value of the pressure signal generator 3 is set to. a pressure alarm setting device which can be taken out as a signal and which can change the set pressure according to the output signal of the number of operating units detector 5; It is a piping alarm that can be input as a signal and can be output as a signal when a change that exceeds a set amount of flow rate change and a set amount of pressure change occurs within a predetermined time. FIG. 2 shows the flow rate-pressure characteristics of the pump, where 101 and 102 are the flow rate-pressure characteristics at the maximum and minimum rotation speeds of the pump, respectively, and 103 is the cavitation limit. 8 in Fig. 1 sets this cavitation limit as an approximate function, so that the setting can be changed depending on the number of pumps in operation, and it can be taken out as a signal when the flow rate/pressure exceeds the cavitation limit. This is a cavitation detection device. In the above configuration, the signal from the pressure signal generator 3 is input to the pressure alarm setting device 6, the piping alarm 7, and the cavitation detection device 8, and the signal from the flow rate signal generator 4 is input to the piping alarm 7 and the cavitation detection device 8. In addition, the signal from the operating number detector 5 is input to the pressure alarm setting device 6 and the cavitation detection device 8, respectively. The output signals of the pressure alarm setting device 6, piping alarm 7, and cavitation detection device 8 are monitored to diagnose whether or not the operating condition of the pump is appropriate.
That is, the details are as follows. Figure 3 is a flow rate-pressure characteristic diagram, and 101a in the figure is a flow rate-pressure characteristic diagram (hereinafter referred to as Q
102a is the Q-H characteristic at the minimum rotation speed when n units are operated, and 103a is the cavitation limit when n units are operated. Also, 101
b, 102b, 103b are pump n+1, respectively
Q-H at maximum rotation speed and minimum rotation speed during platform operation
characteristics, cavitation limit.

104 and 105 are maximum load curves and minimum load curves scheduled on the load side. Here 102a and 1
The pressure at the intersection of 05 is PL _o , and 102b and 105
The intersection of 101a and 104 is PL _o+1 , and the intersection of 101a and 104 is
Let the intersection of PH _o , 101b and 104 be PH _o+1 .
Set these PL _o , PL _o+1 , PH _o , PH _o+1 with the pressure alarm setting device 6, and set PL _o or less when n units are operated, PH _{o or} more when n+1 units are operated, or PL when _o+1 units are operated. If the pressure was below PH _o+1 or above PH _o+1 , an alarm would be issued as the pump operating pressure was abnormal. However, conventional control devices of this type have the following drawbacks. For example, assume that the pump is performing constant pressure control at point P1 in the flow rate-pressure characteristic diagram of FIG. Here, when the load increases due to water leakage in piping, etc., and gradually shifts to an abnormal load, the flow rate increases while the pressure remains constant due to pressure constant control. That is,
Transition from point P1 to point P2. If this transition is within the time and flow rate set by the piping alarm 7, the piping alarm 7 will not operate. Also, as can be seen from Figure 4, point P2 is within the cavitation limit set by the cavitation detection device 8.
It is not within the range of PL _{o or} less and PH _{o or} more set by the pressure alarm setting device 6. Therefore, none of the pressure alarm setting device 6, piping alarm 7, and cavitation detection device 8, which have diagnostic functions, can detect it.
Furthermore, if the pump is operated at point P3 in the characteristic curve as shown in FIG. 5, this point P3 is within the normal range whether the number of pumps in operation is n or n+1. Here, if one of the pumps becomes shut-off operation for some reason when n+1 pumps are in operation, the P3 point can be operated satisfactorily with n units by increasing the rotation speed, so the pump rotation speed should be increased. Rise and maintain driving at P3 point. but,
Although the pump that has reached its cut-off is abnormal, it cannot be detected because it is operating at point P3.

This is because it refers to the criteria for determining the operating state set by the cavitation limit in the Q-H characteristics, the minimum and maximum load curves, and the minimum and maximum rotation speed characteristics of the pump. This is because, since no load curve is set, adjusting the pump rotation speed will result in a flow rate-pressure range that is considered normal.

The present invention takes into account the above-mentioned drawbacks of conventional diagnostic devices, and provides a pump operating state detection device for diagnosing whether or not a pump operating at any rotational speed has a normal flow rate (pressure). This is what we provide.

An embodiment of the present invention will be described with reference to FIGS. 6 to 12. FIG. 6 is a block diagram showing the configuration of this device, in which 1a to 1c are variable speed motors, 2a to 2c are pumps, 4 is a flow signal generator, and 5 is a detector for the number of operating units. This is the same as the one shown in FIG. 1 explained in . 9 is a diagnostic device that diagnoses various operating ranges of the n pumps based on the pump rotation speed and flow rate; 10 is a display device that receives signals from this diagnostic device 9 and displays the current operating state of the pumps; be. 11a~
11c is a rotational speed transmitter for detecting the rotational speed provided in each of the variable speed electric motors 1a to 1c. In the control device having the above configuration, the number of pumps in operation is detected by the number of operating pumps detector 5, and the flow rate is determined by the flow rate signal generator 4.
Each rotational speed signal is input to the diagnostic device 9 from the rotational speed transmitters 11a to 11c. Thereby, the diagnostic device 9 diagnoses and outputs the operating state of the relationship between the number of operating pumps, the number of revolutions, and the flow rate. The display device 10 receives the output signal from the diagnostic device 9 and displays whether it is normal or abnormal.

Next, the operation of this apparatus having the above configuration will be explained.

In a pump driven by a variable speed electric motor, a flow rate-pressure characteristic as shown in FIG. 7 is generally obtained. In the figure, 104 is the maximum load curve in the pump water supply system, 105 is the minimum load curve in the pump water supply system, 101a is the maximum rotation speed curve when n pumps are operated, and 102a is the minimum rotation speed curve when n pumps are operated. , 106a is the minimum flow curve showing the limit which is not very favorable for the pump unless the flow rate exceeds a certain pressure at a certain pressure when n pumps are operated, and 103a is the cavitation limit when n pumps are operated, and In the curve, if the flow rate-pressure is given, the rotation speed is inevitably determined, so the flow rate-pressure curve can be replaced with the rotation speed-flow rate curve. This rotational speed-flow rate curve has a relationship as shown in FIG. That is,
Various curves 101a, 102a, 1 in Fig. 7
03a, 104, 105, 106a are the various curves 101', 102', 103a', respectively in FIG.
104a', 105a', and 106a'. The various curves described above are stored in advance in the diagnostic device 9 as approximate functions with the flow rate and rotational speed as variables for each number of operating vehicles.
Here, the control device shown in FIG.
The flow rate signal is then input to the diagnostic device 9. The diagnostic device 9 selects a function corresponding to the number of operating vehicles from among these signals based on the operating vehicle number signal, and calculates a flow rate limit value corresponding to the rotation speed using this function. This flow rate limit value is compared in magnitude with the flow rate signal from the flow rate signal transmitter 4, and the result is displayed on the display device 10.

In other words, in the area to the right of 101a', the rotational speed is too high, in the area to the left of 102a', the rotational speed is too low, and 10
The region above 3a' is the cavitation limit region, and the region between 103a' and 105' is underload.
104a', 105'a, the maximum rotational speed 101' and the minimum rotational speed 10 when operating the n pumps.
The area surrounded by 2' is normal, 104a' and 106
The area between 106a' and 106a' is considered to be an overloaded area, and the area below 106a' is considered to be a minimum flow limit area. With the above, the operating state of the pump can be accurately known.

By the way, in the above embodiment, the operating condition of the pump was diagnosed based on the discharge flow rate and the rotation speed, but it is also possible to use the discharge pressure (or the differential pressure due to the difference between the suction pressure and the discharge pressure) instead of the discharge flow rate. are equivalent. In this case, the configuration is as shown in FIG. 9, and the relationship between the rotation speed and the discharge pressure (or differential pressure) is as shown in FIG. 10. Flow rate - 6th in rotational speed
FIGS. 9 and 10 show the relationships in FIGS. 9 and 8 replaced with pressure (or differential pressure) versus rotational speed.
That is, instead of the signal from the flow rate signal generator 4 in FIG. 6, the pressure signal generator 3 for detecting pressure on the discharge side in FIG. 9 (or the discharge pressure and suction pressure provided between the pump suction side and the discharge side) A signal from the differential pressure signal generator 3' which outputs the differential pressure as a signal is input to the diagnostic device 9, and the same diagnosis as in the above embodiment is performed and displayed on the display device 10.

Even in this manner, the operating state of the pump can be detected. Generally, the pressure-flow rate relationship on the discharge side of the pump is as shown in FIG. 7, with the minimum load curve being within the cavitation limit and the maximum load curve being below the minimum flow limit. Therefore, if the portion surrounded by the maximum load curve 104, the minimum load curve 105, the maximum rotational speed curve 101a, and the minimum rotational speed curve 102a is regarded as normal, the configuration can be simplified and the same effect can be obtained. In other words, the QH curve in FIG.
(or Figure 10). In this case, what is preset in the diagnostic device 9 in the control device of FIG. 6 (or FIG. 9) is a maximum load curve 104' (or 104''), a minimum load curve 105' (or 105''), All you need is the rotation speed curve 101' (or 101'') and the minimum rotation speed curve 102' (or 102''); if it is above the maximum load curve, the load is too high; if it is below the minimum load curve, it is underload, and if it is above the maximum rotation speed. If so, the number of revolutions is too high; if it is below the minimum number of revolutions, the number of revolutions is too low.
The area surrounded by each curve can be diagnosed as normal. Then, each signal is input to the display device 10 and displayed.

Although the pump operating state can be detected in the above manner, this may also be done in the following manner. That is, in the second modification described above, the operating state of the pump was diagnosed based on the maximum load curve, minimum load curve, maximum rotation speed, and minimum rotation speed, but in the pump water supply system, the diagnosis is made as shown in Figure 5. A relationship may arise. For example, in the relationship shown in FIG. 5, if the operating point is P4, the operation exceeds the cavitation limit when n pumps are operating, and is in the normal range when n+1 pumps are operating. Figure 11 (or 1) replaces the relationship in Figure 5 with rotation speed - flow rate (or pressure)
Figure 2).

In order to diagnose this operating state, a control device is configured as shown in FIG. 6 (or FIG. 9) explained in the above-mentioned embodiment, and the diagnostic device 9 is configured to operate at a maximum rotational speed of 101'.
(or 101''), minimum rotation speed 102' (or 102''), maximum load curve 104a'104b' (or 104a'', 104b'') when n, n+1 pumps are operating, and n, n+1 pumps Minimum load curve 105a', 105 during operation
b′ (or 105a″, 105a″) and n, n+1
Cavitation limits 103a', 103b' (or 103a'', 10
3b'') is set in advance, and diagnosis or display of excessive load, underload, excessive rotation speed, under-rotation speed, cavitation limit, and normality is performed in the same manner as in the previous embodiment.Here, as shown in FIG. In the conventional method of diagnosing based on the characteristic curve, it was not possible to detect abnormal operation at point P3, where one pump is closed when pump n+1 is in operation, but when diagnosing based on the characteristic curve shown in Fig. 11, Since the flow rate at point P3 is too low at the rotational speed when the n+1 unit is in operation (that is, below 104b' in FIG. 11), an excessive load alarm is issued and an abnormal state can be detected. In this way, cavitation limits, minimum and maximum load curves, and minimum and maximum rotation speed characteristics of the pump are obtained for each number of operating pumps, and these are approximated using flow rate or pressure and rotation speed as variables. Based on these characteristic curves, we obtain a state-specific region for determining the operating state, and calculate each limit value corresponding to the number of pumps in operation and the number of pump rotations from the number of pumps in operation and their rotation speed. This is then compared with the detection output related to the discharge flow rate, such as the pump discharge flow rate, discharge pressure, or suction-discharge pressure difference, and it is determined according to the comparison result which of the above-mentioned regions indicating the operating state falls. Since the diagnosis result is displayed by
Conventionally, the cavitation limit in the Q-H characteristics with flow rate and pressure as variables, the minimum and maximum load curves, and the condition discrimination area for determining the operating condition set by the maximum and minimum rotation speed characteristics of the pump are compared. Unlike diagnosis methods that focus on discharge flow rate and pressure, which ignores rotation speed, the diagnosis method focuses on discharge flow rate or pressure and pump rotation speed, taking into account the maximum and minimum loads depending on the number of pumps in operation. When water is supplied by a pump driven by a variable-speed electric motor, abnormal flow rate, abnormal pressure, shut-off operation of the pump, and abnormality of the water supply system can be detected at any rotation speed, and it is possible to detect any abnormality in the operating state. It is possible to accurately diagnose whether

In particular, with detection based on flow rate and pressure, if either detection function becomes disabled, diagnosis and display cannot be performed.However, in the present invention, by employing both flow rate and rotation speed, pressure and rotation speed, one detection function can be detected. Even if the function becomes impossible, it can be backed up, making diagnosis and display possible.Also, in the conventional system using QH characteristics, in order to perform the same function as the present invention, it is necessary to adjust the flow rate, pressure, pump rotation speed, and each Although it is necessary to calculate the Q-H curve of the pump at the rotation speed, the present invention, which uses the rotation speed-flow curve or the rotation speed-pressure coordinate of the pump, calculates the flow rate and rotation speed,
Alternatively, it is possible to provide a pump operating state detection device having excellent features such as being able to accurately diagnose and display the operating state by detecting only pressure and rotation speed.

[Brief explanation of the drawing]

Fig. 1 is a block diagram showing the configuration of a conventional device, Figs. 2 to 5 are Q-H characteristic diagrams for explaining operating state diagnosis in the conventional device, and Fig. 6 shows an embodiment of the present invention. The block diagram, FIGS. 7 and 8 are rotational speed-flow characteristic diagrams for explaining the operating state diagnosis of the present invention, and FIG. 9 is a block diagram showing a modification of the present invention, and FIGS. 10 to 12. is a rotation speed-flow rate and rotation speed-pressure characteristic diagram for explaining the operating condition diagnosis. 1a to 1c...variable speed electric motor, 2a to 2c...pump, 3...pressure signal generator, 3'...differential pressure signal generator,
4...Flow rate signal generator, 5...Operation number detector, 9...
Diagnostic device, 10...display device, 11a-11c...rotation speed transmitter.

Claims (1)

[Scope of Claims] 1. A device for detecting the pump operating state used in pump equipment in which a desired number of pumps is selected from a plurality of pumps and the selected pumps are driven by a variable speed prime mover. an information detection device that detects information regarding the flow rate such as the discharge flow rate or discharge pressure of the driven pump or the differential pressure between the suction pressure and the discharge pressure; an information detection device that detects the number of operating pumps; A rotation speed detection device that detects the rotation speed of the pump, and obtains the minimum and maximum load characteristics of the load side pipe line and the minimum and maximum rotation speed characteristics of the pump in the pump rotation speed - flow rate or pressure characteristics according to the number of pumps in operation. A pump operating state detection device comprising: a device for obtaining a pump operating limit region from these and diagnosing a pump operating state from this, the flow rate related information, and the rotational speed of the pump. 2. The pump operating state detection device according to claim 1, wherein a cavitation limit of the pump is added as a factor for determining the pump operating limit region of the device for diagnosing the pump operating state. 3. The pump operating state detection device according to claim 1, wherein a minimum flow of the pump is added as a factor for determining the pump operating limit region of the device for diagnosing the pump operating state.