Liquid supply device

Abstract

To improve accuracy of detecting a start frequency excess.SOLUTION: A liquid supply device according to an embodiment of the present invention includes a control unit, a current detection unit, a state detection unit, a counting unit, and a start frequency excess detecting unit. The control unit generates a start command for supplying a load current to a motor for driving a pump and a stop command for stopping supply of the load current at timing different from each other. The current detection unit detects the load current. The state detection unit detects an operation state or a stop state of the motor on the basis of the start command or the stop command and output of the current detection unit. The counting unit counts the number of times of detection of the operation state or the stop state on the basis of the output of the state detection unit. The start frequency excess detecting unit detects a start frequency excess of the motor on the basis of the number of times of detection in a time set in advance, and outputs a detection result of the start frequency excess.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a liquid supply device. [Background technology]

[0002] In liquid supply devices such as freshwater submersible pumps, excessive starting frequency, which occurs when the pump starts and stops repeatedly in a short period of time, can cause the motor to accumulate heat and burn out. For this reason, it is desirable for liquid supply devices to detect excessive starting frequency and protect the motor from burning out. Excessive starting frequency is also known as excessive starting frequency or chattering.

[0003] Several methods are known for detecting this type of excessive start frequency. For example, a method is known in which chattering is detected based on the pressure in the flow path when multiple pumps are operated. Another method is known in which, for a pump that repeatedly stops and restarts based on the discharge pressure and water volume, the number of starts (restarts) or stops is counted, and if the number of restarts exceeds a reference value within a measurement period, an excessive start frequency is determined. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6581801 [Patent Document 2] Patent No. 4804747 Summary of the Invention [Problem to be solved by the invention]

[0005] The above-described techniques usually pose no particular problems, but the inventors have found that there is room for improvement in the accuracy of detecting excessive starting frequency.

[0006] SUMMARY OF THE INVENTION An object of the present invention is to provide a liquid supply device that can improve the accuracy of detecting excessive start-up frequency. [Means for solving the problem]

[0007] A fluid supply device according to one aspect of the present invention includes a control unit, a current detection unit, a state detection unit, a counting unit, and an excessive start frequency detection unit. The control unit generates a start command to supply a load current to a motor that drives a pump and a stop command to stop the supply of the load current at different times. The current detection unit detects the load current. The state detection unit detects an operating or stopped state of the motor based on the start command or the stop command and the output of the current detection unit. The counting unit counts the number of times the operating or stopped state is detected based on the output of the state detection unit. The excessive start frequency detection unit detects excessive start frequency of the motor based on the number of detections within a predetermined time period and outputs the detection result of the excessive start frequency. [Effects of the Invention]

[0008] According to the present invention, the accuracy of detecting excessive starting frequency can be improved. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a schematic diagram illustrating the configuration of a pump device according to a first embodiment. [Figure 2] 4 is a flowchart for explaining an example of operation in the first embodiment. [Figure 3] 10 is a flowchart illustrating an example of operation in the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, the embodiments will be described with reference to the drawings. Hereinafter, elements that are identical or similar to elements already described will be designated by the same or similar reference numerals, and duplicate descriptions will generally be omitted. For example, when there are multiple identical or similar elements, a common reference numeral may be used to describe each element without distinguishing between them, or a subnumber and / or lowercase alphabetic character may be used in addition to the common reference numeral to describe each element distinctly.

[0011] For the sake of convenience, the following description will be given using a pump device as an example of a freshwater submersible pump for the liquid supply device. However, the liquid supply device is not limited to freshwater, and may be a pump device that supplies liquids such as sewage, wastewater, hot spring water, or seawater to a destination. The pump device will be described using an example of a submersible pump installed in a water tank or well, but this is not limited to this and may also be a pump directly connected to a water main. The electromagnetic contactor interposed between the power source and the motor will be described using an example where it is held by the control panel, but it may also be located away from the control panel without being held by the control panel.

[0012] First Embodiment 1 is a schematic diagram illustrating the configuration of a pump device according to a first embodiment. This pump device 1 includes a vertical-shaft multi-stage pump 11 that is placed underwater in a well or the like, a motor 12 connected to the pump 11, and an electromagnetic contactor 21 that supplies power to the motor 12 via cables 13 for each phase. The electromagnetic contactor 21 is housed in a control panel 20, and a three-phase, three-wire AC power supply 30 is connected to the input side of the electromagnetic contactor 21 via power supply wiring 14 for each phase. The pump device 1 is an example of a liquid supply device.

[0013] Here, pump 11 is a multi-stage submersible pump for deep wells, placed in, for example, a well, with at least a portion of it located below the surface of the fluid in the well, such as well water. Pump 11 has a rotating shaft, which is connected to the rotor shaft of motor 12. When power is supplied to motor 12, which is placed underwater in a well or the like, the rotor in motor 12 rotates, and the rotating shaft rotates in response to this rotation. The rotation of the rotating shaft of pump 11 rotates impellers in multiple casings, increasing the pressure of the water in the casings and sending the water from the discharge casing to the secondary side of pump 11.

[0014] Motor 12 is, for example, a submersible motor, and is placed, for example, in well water directly below pump 11. Motor 12 is connected to electromagnetic contactor 21 via cable 13. When power is supplied from electromagnetic contactor 21 via cable 13, the rotor of motor 12 rotates, and the rotation of the rotor of pump 11 rotates in response to the rotation, thereby driving pump 11. Motor 12 is an example of a load device.

[0015] The control panel 20 includes an electromagnetic contactor 21, a control unit 22, a memory unit 26, a communication unit 27, an input unit 28, a display unit 29, and a speaker 29a. The control unit 22 includes a voltage detection unit 23, an R-phase current detection circuit 24R, a T-phase current detection circuit 24T, and a microcomputer 25. The voltage detection unit 23, the memory unit 26, the communication unit 27, the input unit 28, the display unit 29, and the speaker 29a may be omitted as appropriate. That is, the control unit 22 and the electromagnetic contactor 21 are an example of a control panel. The control unit 22, the electromagnetic contactor 21, the display unit 29, and / or the speaker 29a are another example of a control panel. The pump 11, the motor 12, and the control panel 20 are an example of a liquid supply device.

[0016] The electromagnetic contactor 21 is controlled by the control unit 22, and supplies power received from the AC power supply 30 via the power supply wiring 14 to the motor 12 via the cable 13. In addition, the electromagnetic contactor 21 closes the contact between the power supply wiring 14 and the cable 13 in response to a start command generated by the control unit 22, thereby supplying a load current to the motor 12. In addition, the electromagnetic contactor 21 opens the contact between the power supply wiring 14 and the cable 13 in response to a stop command generated by the control unit 22, thereby cutting off the supply of load current to the motor 12. The electromagnetic contactor 21 does not necessarily have to be housed in the control panel 20, and may be arranged outside the control panel 20.

[0017] The voltage detection unit 23 detects the three-phase line voltage waveforms based on the three-phase AC voltages input to the electromagnetic contactor 21 that supplies power to the load device, which is the motor 12 that drives the pump 11. Specifically, the voltage detection unit 23 detects the three-phase line voltage waveforms from the power supply wiring 14 between the AC power supply 30 and the electromagnetic contactor 21.

[0018] The R-phase current detection circuit 24R and the T-phase current detection circuit 24T detect current waveforms for two phases of the three-phase AC current output from the electromagnetic contactor 21. Specifically, the R-phase current detection circuit 24R detects the R-phase current waveform from the cable 13 between the electromagnetic contactor 21 and the motor 12 via a current transformer CT_R. Similarly, the T-phase current detection circuit 24T detects the T-phase current waveform from the cable 13 between the electromagnetic contactor 21 and the motor 12 via a current transformer CT_T. Note that the R-phase current detection circuit 24R and the T-phase current detection circuit 24T are not limited to current transformers, and may also detect current waveforms using shunt resistors. The control unit 22 may further include an S-phase current detection circuit. The R-phase current detection circuit 24R and the T-phase current detection circuit 24T are examples of current detection units that detect the load current supplied to the motor 12.

[0019] The microcomputer 25 is a control center that controls all the components within the control panel 20. The microcomputer 25 includes a memory (not shown) that stores programs and data, and a processor (not shown) that executes processing based on the programs and data stored in the memory, thereby achieving various control functions. The microcomputer 25 may be a central processing unit (CPU), a graphics processing unit (GPU), a field programmable gate array (FPGA), a digital signal processor (DSP), or any other general-purpose or dedicated processor.

[0020] The various control functions realized by the microcomputer 25 include, for example, a control function 25a for controlling the pump and a protection function 25b for protecting the pump device 1.

[0021] The control function 25a generates a start command to supply a load current to the motor 12 that drives the pump 11 and a stop command to stop the supply of the load current at different timings. For example, the control function 25a generates a start command or a stop command based on input from the communication unit 27 or the input unit 28. The control function 25a controls the electromagnetic contactor 21 in response to the generated start command or stop command, thereby executing or interrupting the supply of the load current to the motor 12. The control function 25a generates at least one of an alarm and a stop command when it receives a detection result of an excessive start frequency from the protection function 25b. Similarly, the control function 25a generates at least one of an alarm and a stop command when it receives a detection result of an abnormality related to the electromagnetic contactor 21 from the protection function 25b. For example, the control function 25a can generate an alarm and output it from the speaker 29a or the like to prompt maintenance work such as inspection, repair, or replacement in response to the abnormality of the excessive start frequency or the abnormality of the electromagnetic contactor 21. Furthermore, for example, the control function 25a can control the pump 11 to a stopped state by issuing a stop command and interrupting the supply of load current to the motor 12 by the electromagnetic contactor 21. The control function 25a is an example of a control unit.

[0022] The protection function 25b detects excessive starting frequency of the motor 12 based on a start command or stop command generated by the control function 25a and the outputs of the R-phase current detection circuit 24R and the T-phase current detection circuit 24T, and outputs the detection result of the excessive starting frequency to the control function 25a. The protection function 25b may appropriately include a state detection function 25b1, a counting function 25b2, and an excessive starting frequency detection function 25b3, as shown in (i) to (iii) below. The state detection function 25b1, the counting function 25b2, and the excessive starting frequency detection function 25b3 are examples of the functional division of the protection function 25b, and are not limited to this. Similarly, the control function 25a and the protection function 25b are examples of the functional division within the microcomputer 25, and are not limited to this. In other words, between the functions within the microcomputer 25, one function may be executed by another function. For example, the protection function 25b may execute the alarm output function of the control function 25a.

[0023] (i) The state detection function 25b1 detects the running or stopped state of the motor 12 based on the start command or stop command generated by the control function 25a and the outputs of the R-phase current detection circuit 24R and the T-phase current detection circuit 24T.

[0024] Furthermore, the state detection function 25b1 may obtain the values ​​of the load current for three phases based on the outputs of the R-phase current detection circuit 24R and the T-phase current detection circuit 24T, which detect the current waveforms for two phases out of the three-phase load current supplied to the motor 12. For example, the state detection function 25b1 may calculate the current waveform for one undetected phase based on the instantaneous currents in the current waveforms for two phases and the fact that the sum of the instantaneous currents for the three phases including the instantaneous currents is zero, and obtain the value of the load current according to the values ​​of the instantaneous currents for the three phases based on the obtained calculation result. The state detection function 25b1 is an example of a state detection unit.

[0025] (ii) The counting function 25b2 counts the number of times the operating or stopped state is detected based on the output of the state detection function 25b1. For example, the counting function 25b2 counts the number of times the operating state is detected based on the output of the state detection function 25b1 that detected the operating state. Alternatively, the counting function 25b2 counts the number of times the stopped state is detected based on the output of the state detection function 25b1 that detected the stopped state. In other words, the number of times the motor 12 has been in an operating state may be counted as the number of times the motor 12 has been in a stopped state. The operating state of the motor 12 may be referred to as a motor operating state. The stopped state of the motor 12 may be referred to as a motor stopped state. The counting function 25b2 is an example of a counting unit.

[0026] (iii) Excessive start frequency detection function 25b3 detects the excessive start frequency of motor 12 based on the number of detections within a preset time period (hereinafter also referred to as the set time period), and outputs the detection result of the excessive start frequency to control function 25a. For example, excessive start frequency detection function 25b3 may detect the excessive start frequency of motor 12 when the number of detections exceeds a set number within the set time period. Excessive start frequency detection function 25b3 is an example of an excessive start frequency detection unit.

[0027] In addition to the functions (i) to (iii), protection function 25b may calculate the power supply voltage unbalance rate based on the output of voltage detection unit 23, and detect an abnormality related to the power supply voltage unbalance rate when the power supply voltage unbalance rate is greater than a threshold value. Similarly, protection function 25b may detect a line voltage where a sine waveform is not detected based on the output of voltage detection unit 23, and derive which of the three phases is in an open phase state, R phase, S phase, or T phase, according to the detected line voltage, thereby detecting an abnormality related to a missing phase. Protection function 25b may also output the detection result of the abnormality to control function 25a. In this case, control function 25a may issue at least one of an alarm and a stop command when it receives the detection result of the abnormality, as described above.

[0028] The storage unit 26 is, for example, an EEPROM (registered trademark) (Electrically Erasable Programmable Read-Only Memory) or an HDD (Hard Disk Drive). The storage unit 26 stores data that is not stored in the memory of the microcomputer 25. For example, the storage unit 26 stores data for long-term storage rather than data used for real-time control, such as a log of operation data of the pump device 1, a log of abnormality detection, and maintenance information. However, the storage unit 26 is not limited to this, and may store data used for real-time control, such as control parameters and thresholds.

[0029] The communication unit 27 is an arbitrary communication interface controlled by the control unit 22 and capable of communicating with an external device such as a communication terminal using a wireless communication technology. Specifically, the communication unit 27 can be connected to an external device such as a communication terminal using, for example, a (short-range) wireless communication technology such as the Bluetooth (registered trademark) Low Energy standard (hereinafter also referred to as the BLE standard), Wi-Fi (registered trademark), or NFC, or a wired communication technology such as USB. The communication unit 27 may also wirelessly connect a speaker 29a, a microphone, etc. using the BLE standard. Note that the BLE standard may be BLE version 4.0 or higher and may be compatible with the BLE communication method. Accordingly, the "BLE standard" may also be referred to as the "Bluetooth 4.0 or higher standard."

[0030] The input unit 28 may include, for example, a device for receiving user input, such as an operation panel or touch screen including button switches and select switches, and sensors such as a water level sensor and a float switch (not shown). The select switch is used to input a pump operation command, and a switch for switching the pump between automatic, stop, and manual modes can be used as appropriate in response to user operation.

[0031] Display unit 29 may include a display device such as a liquid crystal display or an organic EL display that displays moving images, still images, text, alarms, etc. in accordance with processing by microcomputer 25, or an LED (Light Emitting Diode) lighting unit that displays the status of pump device 1. The display device may also have the function of input unit 28, such as a touch screen. Display unit 29 is an example of an output unit that is controlled by control function 25a and outputs an alarm.

[0032] The speaker 29a is a device that outputs audio such as an alarm or a guide based on audio information sent from the control unit 22, and may be embedded in the control panel 20, placed on the floor, or hung on a wall. The speaker 29a can be connected to the control unit 22 via a wire or wirelessly. The speaker 29a is another example of an output unit that is controlled by the control function 25a and outputs an alarm.

[0033] Next, an example of the operation of the pump device configured as above will be described with reference to the flowchart of FIG.

[0034] In step ST1, the microcomputer 25 in the control panel 20 of the pump device 1 generates a start command or a stop command based on, for example, an input from the communication unit 27 or the input unit 28. Alternatively, the microcomputer 25 generates a stop command based on the result of an abnormality detected by the protection function 25b. Thereafter, the microcomputer 25 sends the generated start command or stop command to the electromagnetic contactor 21.

[0035] Meanwhile, the electromagnetic contactor 21 changes the open / close state of the contacts depending on whether a start command or a stop command has been received. That is, if the electromagnetic contactor 21 does not receive the generated command (ST1: No), it maintains the current open / close state of the contacts and waits until it receives a command. On the other hand, if the electromagnetic contactor 21 receives the generated command (ST1: Yes), it proceeds to step ST2.

[0036] After step ST1, in step ST2, the electromagnetic contactor 21 starts or stops the motor 12 in response to a command received from the microcomputer 25. Specifically, the electromagnetic contactor 21 closes its contacts in response to the received start command, thereby supplying a load current to the motor 12. On the other hand, the electromagnetic contactor 21 opens its contacts in response to the received stop command, thereby interrupting the supply of a load current to the motor 12.

[0037] After step ST2, in step ST3, the control panel 20 uses the R-phase current detection circuit 24R and the T-phase current detection circuit 24T to detect the current waveforms of two of the three AC phases output from the electromagnetic contactor 21. The microcomputer 25 calculates the current waveform of the undetected S-phase based on the current waveforms of the two phases indicated by the outputs of the R-phase current detection circuit 24R and the T-phase current detection circuit 24T. Specifically, the microcomputer 25 calculates the current waveform of the undetected S-phase based on the instantaneous currents of the two current waveforms and the fact that the sum of the instantaneous currents of the three phases, including the instantaneous currents, is zero. This allows the microcomputer 25 to obtain current waveforms for three phases. The microcomputer 25 also calculates the value of the load current based on the values ​​of the instantaneous currents of the three current waveforms. The load current value may be, for example, an effective value. Step ST3 is performed when the supply of load current is executed in step ST2. That is, step ST3 is not performed if the supply of load current is interrupted in step ST2.

[0038] After step ST3, in step ST4, the microcomputer 25 determines whether or not a load current has been detected, and proceeds to step ST5 or ST6 depending on the determination result.

[0039] If the determination result in step ST4 is negative (ST4: No), in step ST5, the microcomputer 25 determines that the motor 12 is in a stopped state, counts the number of times the motor is in a stopped state, and proceeds to step ST7.

[0040] On the other hand, if the result of the determination in step ST4 is that a load current is detected (ST4: Yes), in step ST6, the microcomputer 25 determines that the motor 12 is in an operating state, and counts the number of times the motor operating state has been detected.

[0041] After step ST6, in step ST7, the microcomputer 25 determines whether the number of detections counted within the set time exceeds the set number of times. If the result of this determination is no (ST7: No), the process returns to step ST1 and the processes of steps ST1 to ST7 are repeatedly executed.

[0042] On the other hand, if the result of the determination in step ST7 is that the number of detections exceeds the set number of times (ST7: Yes), in step ST8, the microcomputer 25 detects that the motor 12 is being started too frequently and determines that the pump device 1 is in an abnormal state.

[0043] After step ST8, the microcomputer 25 generates a stop command based on the result of the detection of the excessive start frequency, and sends the stop command to the electromagnetic contactor 21 to cut off the supply of load current to the motor 12, thereby forcibly stopping the pump 11. Note that in addition to or instead of the forcible stop, the microcomputer 25 may output an alarm from the speaker 29a or the like based on the result of the detection of the excessive start frequency.

[0044] As described above, according to the first embodiment, the liquid supply device includes a control unit, a current detection unit, a state detection unit, a counting unit, and an excessive start frequency detection unit. The control unit generates a start command to supply a load current to the motor 12 that drives the pump 11 and a stop command to stop the supply of the load current at different timings. The current detection unit detects the load current. The state detection unit detects the operating or stopped state of the motor 12 based on the start command or stop command and the output of the current detection unit. The counting unit counts the number of times the operating or stopped state is detected based on the output of the state detection unit. The excessive start frequency detection unit detects excessive start frequency of the motor 12 based on the number of detections within a predetermined time period and outputs the detection result of the excessive start frequency.

[0045] Therefore, when detecting excessive starting frequency of the motor 12, the accuracy of detecting excessive starting frequency can be improved by a configuration that detects the operating state or stopped state with high accuracy based on detection of the load current to the motor 12. Additionally, according to the first embodiment, the operating or stopped state of the motor can be detected more directly compared to conventional technology in which excessive starting frequency (chattering) is detected based on the pressure or water volume in the flow path, so the accuracy of detecting excessive starting frequency can be improved.

[0046] Furthermore, according to the first embodiment, the control unit may issue at least one of an alarm and a stop command when it receives a detection result of excessive starting frequency. In this case, in addition to the effects described above, it is possible to prevent motor burnout due to excessive starting frequency. For example, when an alarm is issued, it is possible to prompt the user to take action to address the excessive starting frequency. Furthermore, when a stop command is issued, it is possible to protect the motor from burnout by stopping the motor that is starting too frequently.

[0047] Furthermore, according to the first embodiment, the current detection unit may detect current waveforms for two phases out of the three-phase load currents supplied to the motor. The state detection unit may calculate the current waveform for the one undetected phase based on the instantaneous currents in the current waveforms for the two phases and the fact that the sum of the instantaneous currents for the three phases, including the instantaneous currents, is zero, and obtain the value of the load current according to the instantaneous current values ​​for the three phases based on the calculation result. In this case, in addition to the above-mentioned effects, the hardware configuration for detecting the current waveform for one phase (e.g., an S-phase current transformer and an S-phase current detection circuit) can be omitted. Additionally, the current waveforms for three phases can be obtained using the current transformers and current detection circuits for two phases.

[0048] <Second embodiment> The second embodiment is a specific example of the first embodiment, and is an embodiment that aims to improve the accuracy of detecting excessive activation frequency by using multiple judgment values. Note that the second embodiment is capable of detecting not only excessive activation frequency abnormalities but also other abnormalities by using multiple judgment values.

[0049] Specifically, for example, the state detection function 25b1 of the microcomputer 25 may detect the operating state as either the operating state or the stopped state when, in response to a start command, the load current value momentarily exceeds a starting current judgment value set higher than the maximum current value during continuous operation, and then exceeds a minimum current judgment value during continuous operation set lower than the starting current judgment value, and falls below the starting current judgment value, until a stop command is issued. Note that each judgment value is preset to a value that satisfies the relationship "minimum current judgment value during continuous operation<maximum current value during continuous operation<starting current judgment value<motor starting current (load current that flows momentarily)."

[0050] Furthermore, for example, if the load current value exceeds the minimum current judgment value even after a stop command is generated, state detection function 25b1 may detect an abnormality related to electromagnetic contactor 21, which cuts off the supply of load current in response to the stop command, and output the detection result of the abnormality. The abnormality related to electromagnetic contactor 21 here is welding of the contacts in the electromagnetic contactor. Note that each judgment value is preset to a value that satisfies the relationship "minimum current judgment value during continuous operation < load current when contacts are welded ≦ maximum current value during continuous operation."

[0051] Furthermore, for example, if the load current value momentarily exceeds the starting current determination value in response to a start command and then exceeds an abnormality determination value that is set lower than the starting current determination value and higher than the maximum current value during continuous operation, the state detection function 25b1 may detect an abnormality related to the electromagnetic contactor 21 that executes the supply of load current in response to the start command and output the detection result of the abnormality. The abnormality related to the electromagnetic contactor 21 here refers to wear of the contacts in the electromagnetic contactor 21. Note that each determination value is preset to a value that satisfies the relationship "maximum current value during continuous operation < abnormality determination value < load current when contacts are worn < starting current determination value < motor starting current." Furthermore, without being limited to this, the abnormality determination value may be set to the same value as the maximum current value during continuous operation.

[0052] The other configurations are the same as those in the first embodiment.

[0053] Next, an example of the operation of the pump device configured as above will be described with reference to the flowchart of Fig. 3. In Fig. 3, step numbers related to the step numbers in Fig. 2 are suffixed with lowercase English letters.

[0054] In steps ST1a and ST1b, the microcomputer 25 in the control panel 20 of the pump device 1 generates a start command or a stop command based on, for example, an input from the communication unit 27 or the input unit 28. Alternatively, the microcomputer 25 generates a stop command based on the result of an abnormality detected by the protection function 25b. Thereafter, the microcomputer 25 sends the generated start command or stop command to the electromagnetic contactor 21.

[0055] On the other hand, the electromagnetic contactor 21 changes the open / closed state of the contacts depending on whether a start command or a stop command has been received. That is, if the electromagnetic contactor 21 has received a start command (ST1a: Yes), it proceeds to step ST2a and sets the contacts to a closed state. If the electromagnetic contactor 21 has not received a start command (ST1a: No) or has received a stop command (ST1b: Yes), it proceeds to step ST2b and sets the contacts to an open state. If neither a start command nor a stop command has been received (ST1b: No), the electromagnetic contactor 21 maintains the current open / closed state of the contacts and returns to step ST1a.

[0056] After step ST1a, in step ST2a, the electromagnetic contactor 21 starts the motor 12 in response to the start command received from the microcomputer 25. Specifically, the electromagnetic contactor 21 closes the contacts in response to the received start command, and supplies a load current to the motor 12.

[0057] After step ST2a, step ST3 is executed in the same manner as described above.

[0058] After step ST3, in steps ST4a and ST4b, the microcomputer 25 detects the operating state as either an operating or stopped state if, in response to a start command, the load current momentarily exceeds a starting current determination value set higher than the maximum current value during continuous operation, and then exceeds a minimum current determination value during continuous operation set lower than the starting current determination value, and falls below the starting current determination value, until a stop command is issued. For example, in step ST4a, the microcomputer 25 determines whether or not a load current value that momentarily exceeds the starting current determination value has been detected in response to the start command. If not (ST4a: No), the microcomputer 25 skips steps ST4b and ST6 and proceeds to step ST7. On the other hand, if the load current momentarily exceeds the starting current determination value (ST4a: Yes), the microcomputer 25 proceeds to step ST4b.

[0059] After step ST4a, in step ST4b, the microcomputer 25 determines whether a load current value between the starting current determination value and the minimum current determination value during continuous operation has been detected, and if not (ST4b: No), it skips step ST6 and proceeds to step ST7. On the other hand, if a load current value between the starting current determination value and the minimum current determination value has been detected (ST4b: Yes), it proceeds to step ST6.

[0060] After step ST4b, in step ST6, the microcomputer 25 determines that the motor 12 is in an operating state, counts the number of times the motor operating state has been detected, and then proceeds to step ST7.

[0061] On the other hand, after step ST1b, in step ST2b, the electromagnetic contactor 21 opens the contacts in response to the received stop command, and cuts off the supply of load current to the motor 12.

[0062] After step ST2b, in steps ST4c and ST8a, if the load current value exceeds the minimum current judgment value even after the stop command is generated, the microcomputer 25 detects an abnormality related to the electromagnetic contactor 21, which cuts off the supply of load current in response to the stop command. For example, in step ST4c, the microcomputer 25 determines whether or not a load current value exceeding the minimum current judgment value has been detected. If the result of the determination in step ST4c is that a load current value has been detected (ST4c: Yes), in step ST8a, the microcomputer 25 detects an abnormality in which the load current is not cut off in response to the stop command, and determines that an abnormal situation has occurred in which the contacts of the electromagnetic contactor 21 are welded. Thereafter, the process proceeds to step ST9. On the other hand, if the result of the determination in step ST4c is No, the process proceeds to step ST5.

[0063] After step ST4c, in step ST5, the microcomputer 25 determines that the motor 12 is in a stopped state, counts the number of times the motor is in a stopped state, and then proceeds to step ST7.

[0064] In step ST7, the microcomputer 25 determines whether the number of detections counted within the set time exceeds the set number of times. If the result of this determination is no (ST7: No), the process proceeds to step ST7a.

[0065] After step ST7, in steps ST7a and ST8c, the microcomputer 25 detects an abnormality in the electromagnetic contactor 21, which supplies the load current in response to the start command, if the load current exceeds an abnormality determination value that is set lower than the starting current determination value and higher than the maximum current value during continuous operation. For example, in step ST7a, the microcomputer 25 determines whether or not a load current value exceeding the abnormality determination value has been detected. If the result of the determination in step ST7a is that a load current value has been detected (ST7a: Yes), in step ST8c, the microcomputer 25 detects an abnormality in which a load current higher than the maximum current value is flowing, and determines that an abnormal state is due to wear of the contacts of the electromagnetic contactor 21. Thereafter, the process proceeds to step ST9. On the other hand, if the result of the determination in step ST7a is negative (ST7a: No), the process proceeds to step ST1a, where the processes of steps ST1a to ST7 are repeatedly executed.

[0066] On the other hand, if the result of the determination in step ST7 is that the number of detections exceeds the set number of times (ST7: Yes), in step ST8b, the microcomputer 25 detects that the motor 12 is being started too frequently and determines that the pump device 1 is in an abnormal state.

[0067] After step ST8a, ST8b, or ST8c, in step ST9, the microcomputer 25 generates at least one of an alarm and a stop command when it receives the abnormality detection result. For example, after step ST8a, the microcomputer 25 generates a stop command based on the contact welding detection result and sends the stop command to a ground fault circuit interrupter (not shown) arranged upstream of the electromagnetic contactor 21 to cut off the supply of load current to the motor 12, thereby forcibly stopping the pump 11. After step ST8b, the microcomputer 25 executes step ST9 in the same manner as described above. After step ST8c, the microcomputer generates a stop command based on the contact wear detection result and sends the stop command to the electromagnetic contactor 21 to cut off the supply of load current to the motor 12, thereby forcibly stopping the pump 11. Note that after any of steps ST8a to ST8c, in step ST9, an alarm may be output from the speaker 29a or the like in addition to or instead of the forced stop.

[0068] As described above, according to the second embodiment, the state detection unit detects the operating state (operating or stopped) when, in response to a start command, the load current momentarily exceeds a starting current threshold, which is set higher than the maximum current value during continuous operation. The load current then exceeds a minimum current threshold during continuous operation, which is set lower than the starting current threshold, and falls below the starting current threshold until a stop command is issued. The counter counts the number of times the operating state is detected based on the output of the state detection unit that detected the operating state. Therefore, in addition to the aforementioned advantages, one normal operation is detected by detecting the operating current only at startup after detecting a momentary overload, thereby enabling one normal operation to be detected with higher accuracy. Furthermore, the configuration that detects a starting current that flows temporarily at several times the rated current during motor startup allows for more direct detection of motor startup compared to the first embodiment, further improving the accuracy of detecting excessive starting frequency.

[0069] Furthermore, according to the second embodiment, if the load current value exceeds the minimum current judgment value even after a stop command is issued, the state detection unit detects an abnormality related to the electromagnetic contactor that cuts off the supply of load current in response to the stop command and outputs the detection result of the abnormality. In this case, it may be inferred that the abnormality related to the electromagnetic contactor is welding of the contacts in the electromagnetic contactor. This makes it possible to detect an abnormality related to an electromagnetic contactor that cannot cut off the load current after a stop command is issued, in addition to the effects described above. Furthermore, it can be inferred that the electromagnetic contactor cannot cut off the load current even if a stop command is issued because the contacts are welded.

[0070] Furthermore, according to the second embodiment, when the load current momentarily exceeds the starting current threshold in response to a start command and then exceeds an abnormality threshold set lower than the starting current threshold and higher than the maximum current value during continuous operation, the state detection unit detects an abnormality related to the electromagnetic contactor that supplies the load current in response to the start command and outputs the abnormality detection result. In this case, it may be inferred that the abnormality related to the electromagnetic contactor is wear of the contacts in the electromagnetic contactor. This makes it possible to detect an abnormality in an electromagnetic contactor that supplies a load current higher than the maximum current value, in addition to the effects described above. Furthermore, it is possible to infer that the load current value is higher than the maximum current value due to wear of the contacts of the electromagnetic contactor (increased contact resistance due to rough contacts).

[0071] Furthermore, according to the second embodiment, when the control unit receives the abnormality detection result, it issues at least one of an alarm and a stop command. This not only achieves the above-mentioned effects, but also makes it possible to prevent a malfunction of the motor 12 caused by an abnormality in the electromagnetic contactor. For example, when an alarm is issued, it is possible to prompt a response to the abnormality in the electromagnetic contactor. Furthermore, when a stop command is issued, it is possible to protect the liquid supply device from malfunction by stopping the electromagnetic contactor in an abnormal state.

[0072] (Variation) In the embodiment, the case where the invention is applied to one pump 11 has been exemplified, but the invention is not limited to this and may be applied to a configuration of increasing / decreasing pumps, in which each of a plurality of pumps is started or stopped.

[0073] In addition, although the embodiment exemplifies a vertical-axis multi-stage pump 11, the present invention is not limited to this and may be applied to, for example, a horizontal-axis multi-stage pump, a vertical-axis single-stage pump, or a horizontal-axis single-stage pump. In addition, although the embodiment exemplifies a submersible pump, the present invention is not limited to this and may be applied to any pump device such as various land pumps.

[0074] The above-described embodiments are merely illustrative examples for aiding in understanding the concept of the present invention, and are not intended to limit the scope of the present invention. Various components may be added, deleted, or converted to the embodiments without departing from the spirit of the present invention.

[0075] In the above-described embodiment, several functional units have been described, but these are merely examples of implementation of each functional unit. For example, multiple functional units described as being implemented in one device may be implemented across multiple separate devices, and conversely, multiple functional units described as being implemented across multiple separate devices may be implemented in one device.

[0076] The liquid supply device as described above may also be expressed as shown in the following [1] to [5].

[0077] [1] A liquid supply device that supplies liquid by driving a motor in response to start and stop commands from a control unit, in which the state of power supply to the liquid supply device is determined to be the operating state or stopped state of the motor by detecting the presence or absence of motor load current, and if the number of times the operating state or stopped state is detected within a preset time exceeds a preset number, the liquid supply device including the motor or the control unit is determined to be in an abnormal state and is forced to stop or an external alarm is issued. In this way, if the number of times the operating state or stopped state is detected within a set time exceeds the set number, when determining that an abnormal state of excessive starting frequency is present, the operating state or stopped state can be detected with high accuracy by detecting the current, thereby improving the accuracy of detecting excessive starting frequency.

[0078] [2] In the liquid supply device described in [1] above, the protection function uses a first set load current value (starting current judgment value) that is preset higher than the maximum operating current value for continuous operation for detecting the motor starting current, and a second set load current value (minimum current judgment value) that is preset lower than the first set load current value for detecting the minimum operating current value, and if a current value that exceeds the first set load current value is detected for an instant after a motor start command is issued from the control unit, and then a current value that exceeds the second set load current value is continuously detected and operated until a stop command is issued from the control unit, the liquid supply device determines that the start frequency is excessive, and performs a forced stop or issues an external alarm. In this way, one normal operation cycle is detected by detecting the operating current after detecting an instantaneous overload only at startup, so that one normal operation cycle can be detected with higher accuracy.

[0079] [3] In the above [1] or [2], the protection function detects at least two-phase current as the motor current value, and when two-phase current is detected, determines three-phase current using "U phase + V phase + W phase = 0 [A]." In this way, by utilizing the instantaneous current relationship of "U phase + V phase + W phase = 0 A," it is possible to measure three-phase AC current from the current detection results for two phases.

[0080] [4] In any of the above [1] to [3], the protection function determines that the contacts of the electromagnetic contactor have welded and performs a forced stop or issues an external alarm when a current value exceeding the second set load current is detected even after a stop command is issued from the control unit. In this way, when a current is detected after a stop command (stop signal) is issued, it is possible to infer that the electromagnetic contactor has welded.

[0081] [5] In any of [1] to [3] above, the protection function uses a third set load current value (abnormality determination value) that is lower than the first set load current value and higher than the maximum continuous operation current value. After a motor start command is issued from the control unit, the protection function detects the first set load current value even for an instant. If the first set load current value is exceeded, the protection function determines that the contacts of the electromagnetic contactor have worn out, and performs a forced stop or issues an external alarm to protect the control panel. In this way, if the starting current is detected and an excess of the maximum current value is detected, a contact failure of the electromagnetic contactor can be inferred. Note that, since it is sufficient to detect an excess of the maximum current value, the third set load current value (abnormality determination value) may be set to the same value as the maximum continuous operation current value.

[0082] The present invention is not limited to the above-described embodiments, and various modifications can be made in the implementation stage without departing from the spirit of the invention. Furthermore, the embodiments may be implemented in appropriate combinations, in which case the combined effects can be obtained. Furthermore, the above-described embodiments include various inventions, and various inventions can be extracted by combining selected elements from the disclosed elements. For example, if the problem can be solved and the desired effect can be obtained even if some elements are deleted from all elements shown in the embodiments, the configuration from which these elements are deleted can be extracted as an invention. [Explanation of symbols]

[0083] 1 pump device, 11 pump, 12 motor, 13 cable, 14 power supply wiring, 20 control panel, 21 electromagnetic contactor, 22 control unit, 23 voltage detection unit, 24R R-phase current detection circuit, 24T T-phase current detection circuit, 25 microcomputer, 25a control function, 25b protection function, 25b1 status detection function, 25b2 counting function, 25b3 excessive start frequency detection function, 26 memory unit, 27 communication unit, 28 input unit, 29 display unit, 29a speaker.

Claims

1. a control unit that generates a start command for supplying a load current to a motor that drives a pump and a stop command for stopping the supply of the load current at different timings; a current detection unit that detects the load current; a state detection unit that detects an operating or stopped state of the motor based on the start command or the stop command and an output of the current detection unit; a counting unit that counts the number of times the operating or stopped state is detected based on an output of the state detection unit; an excessive start frequency detection unit that detects an excessive start frequency of the motor based on the number of detections within a predetermined time period and outputs a detection result of the excessive start frequency; A liquid supply device comprising:

2. the state detection unit, in response to the start command, detects an operating state of the operating state or the stopped state when the value of the load current momentarily exceeds a starting current determination value set higher than a maximum current value during continuous operation, and then exceeds a minimum current determination value during continuous operation set lower than the starting current determination value and falls below the starting current determination value until the stop command is generated; The counting unit counts the number of times the driving state is detected based on an output of the state detection unit that detected the driving state. The liquid supply device according to claim 1 .

3. When the value of the load current exceeds the minimum current determination value even after the stop command is issued, the state detection unit detects an abnormality related to an electromagnetic contactor that cuts off the supply of the load current in response to the stop command, and outputs a detection result of the abnormality. The liquid supply device according to claim 2 .

4. The abnormality related to the electromagnetic contactor is welding of the contacts in the electromagnetic contactor. The liquid supply device according to claim 3.

5. When the value of the load current momentarily exceeds the starting current determination value in response to the start command and then exceeds an abnormality determination value that is set lower than the starting current determination value and higher than the maximum current value during continuous operation, the state detection unit detects an abnormality related to an electromagnetic contactor that executes the supply of the load current in response to the start command and outputs the detection result of the abnormality. The liquid supply device according to claim 2 .

6. The abnormality related to the electromagnetic contactor is wear of the contacts in the electromagnetic contactor. The liquid supply device according to claim 5.

7. The liquid supply device described in claim 3 or 4, wherein when the control unit receives the detection result of the abnormality, it generates at least one of an alarm and a stop command to send to a ground fault circuit interrupter arranged upstream of the electromagnetic contactor to cut off the supply of load current to the motor.

8. The liquid supply device according to claim 1 , wherein the control unit issues at least one of an alarm and the stop command when receiving a detection result of the excessive start frequency.

9. the current detection unit detects current waveforms of two phases of a load current of three phases supplied to the motor; the state detection unit calculates the current waveform for the one phase that has not been detected based on the instantaneous currents of the two phases and the fact that the sum of the instantaneous currents for the three phases including the instantaneous currents is zero, and obtains the value of the load current according to the values ​​of the instantaneous currents for the three phases based on the calculation result obtained; The liquid supply device according to any one of claims 1 to 6.

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