JPH08254195A - Water feeding device using variable speed pump - Google Patents

Abstract

PURPOSE: To provide a water feeding device reducing a fear of stopping of water feed. CONSTITUTION: In a water feeding device comprising a plurality of inverter devices 200 and 220 having a protection function; a plurality of motors 401 and 402 to perform variable speed operation by a feed from the inverter devices; and a plurality of pumps 411 and 412, a pump control device 300 is provided with a restarting means to return a stopped inverter device to an operation state is arranged at during the stop of operation of the inverter devices 200 and 220. A source switching circuit 350 is arranged between the motors 401 and 402 between the outputs of the inverter devices 200 and 220 and the inputs of the motors 401 and 402. When the inverter devices 200 and 220 are stopped, the starting of a stop inverter device is repeated at least two times by a restarting means, and the source switching circuit 350 switches the output of the inverter to a normal motor when abnormality occurs to the motors 401 and 402 or the pumps 411 and 412.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a water supply device using a hoop which is driven at a variable speed by an inverter device having a protective function, and more particularly to a water supply device suitable for water supply facilities.

[0002]

2. Description of the Related Art In the prior art of a water supply device using a variable speed pump, for example, Japanese Patent Laid-Open Nos. 60-62681 and 6-SHO.
As described in JP-A Nos. 2-232180 and 61-99693, the operating speed of the electric motor that drives the pump is changed by the inverter device according to the fluctuation of the water demand, and the pressure on the discharge side of the pump is changed. Is maintained in a constant relationship (constant discharge pressure or constant end pressure) to supply water.

Further, an inverter device combined with this type of water supply device is disclosed in, for example, Japanese Patent Application Laid-Open No. 57-6576.
JP-A-58-224575 and JP-A-59-185.
170, JP-A-60-84972, JP-A-61-2
As described in each publication of No. 24876, various protection circuits are usually incorporated in order to protect the inverter device itself, and the same applies to a motor or a pump driven by the inverter device. It is customary to incorporate electrical protection means such as a relay or an earth leakage breaker and pump abnormality detection means by a pressure switch.

Therefore, in a water supply device incorporating an inverter device having such a protection function, the protection function is activated due to various factors (instantaneous power failure, overload, temperature rise, noise mixing, etc.) to operate the inverter device. Will stop. Further, if the electric motor or pump fails, the inverter device will stop even if it is normal.

Therefore, conventionally, in such a case,
A device is known in which the pump driving electric motor is switched from an inverter operation to a constant speed operation by a commercial power source to avoid water cutoff.
This will be described with reference to FIG. The prior art shown in FIG. 5 is provided with one inverter device 200, and thereby two motors are provided.
(Induction motor) A water supply device in which two pumps 411 and 412 driven by 401 and 402 are used, and the pumps 411 and 412 are driven at a variable speed to perform water supply by constant discharge pressure control. Is a commercial power source, and the inverter device 200 is operated by receiving three-phase AC power from the commercial power source 100.

The inverter device 200 has the following configuration. A converter circuit 201 that receives three-phase AC power from the commercial power supply 100 via terminals U, V, W and converts the AC power into DC power. An inverter circuit 202 composed of a transistor bridge or the like for reconverting the DC power converted by the converter circuit 201 into AC power. A smoothing capacitor 203 for smoothing the DC power converted by the converter circuit 201. A current detector 204 for detecting the current supplied to the inverter circuit 202. An inverter control circuit 205 that controls the reconversion operation of the inverter circuit 202 based on an operation command (including a speed command) from the outside.

An inverter control circuit 205 and a control power supply circuit 206 for supplying control power to other parts.

A smoothing capacitor 207 connected to the output side of the control power supply circuit 206. A protection circuit 208 that detects the occurrence of a trouble in continuing the operation of the inverter circuit 202 and stops the reconversion operation of the inverter circuit 202. Terminals X, Y, Z for outputting variable frequency AC power of the inverter circuit 202.

The inverter device 2 having such a configuration
00 is well known, so a detailed description of its operation will be omitted, but if a little explanation is added, first, the control power supply circuit 206 determines that the AC power from the commercial power supply 100 or the DC power from the converter circuit 201. Is supplied to each place in the inverter device 200 to supply necessary control power.

Further, the protection circuit 208 includes an input voltage of the converter circuit 201, an input voltage of the inverter circuit 202,
Alternatively, the input current, the temperature in the inverter circuit 202, the control operation in the inverter control circuit 205, etc. are constantly monitored,
If a power failure, undervoltage, overvoltage, overcurrent, overheat, malfunction of control sequence, etc. is detected, the inverter control circuit 2
The function of directly stopping the reconversion operation of the inverter circuit 202 via 05.

Next, reference numeral 300 denotes a pump control device, which serves to perform various controls so that the pressure of the supply water discharged from the pump has a predetermined fixed relationship.
The microcomputer 301 includes a central processing unit 301, a memory (including ROM and RAM) 302, an interface circuit 303, which are mutually connected by a data bus (including an address bus) 304. At the same time, it is configured by a power supply circuit, a clock generation circuit and the like which are not shown.

In the ROM area of the memory 300,
A control program for controlling the pump, a control program for managing the inverter device, and the like are stored in advance, and a work area necessary for continuing the arithmetic processing of the central processing unit 301 is stored in the RAM area. Reserved.

In the interface circuit 303, an A / D converter for converting external analog data into digital data, a D / A converter for converting internal digital data into analog data, and a data transfer interface. Latch circuits, transistor relay circuits for signal amplification, etc. are prepared as necessary. 305 is a switch group for performing initial setting of the pump control device 300,
It is connected to the interface circuit 303.

Reference numeral 400 denotes a water supply section, which is provided with the motors 401 and 402 and the first and second pumps 411 and 412 connected to the motors 401 and 402, respectively, as described above. A water supply pipe 403 commonly connected to the discharge side via a check valve and a gate valve, a pressure tank 404 connected to the water supply pipe 403, a pressure detector 405, and the like.

Reference numeral 350 denotes a power source switching circuit, which is a commercial power source 100.
And the water supply unit 400, and between the inverter device 200 and the water supply unit 400, the operation of which is controlled by an opening / closing command from the pump control device 300.
1 to 354, the contact 351 connects the motor 401 to the commercial power supply 100, the contact 352 connects the motor 401 to the inverter device 200, and the contact 353 connects the motor 402 to the commercial power supply 10.
0, the contact 354 connects the motor 402 to the inverter device 20.
Connect to 0 respectively.

More specifically, reference numeral 210 is a discharge resistor, which is connected to the output of the control power supply circuit 206 by closing the contact 209 during the protection operation of the inverter device 200 and charges the electric charge remaining in the smoothing capacitor 207. Works to

In order to guarantee the operation of the inverter device 200 when the power is turned on or during the protection operation, the potential of the control power supply circuit 206 side is normally set after the potential of the output side of the converter circuit 201 is established when the power is turned on. When the protection operation is performed, the potential on the control power supply circuit 206 side is ensured so that the protection operation is ensured for a sufficiently long period even after the potential on the converter circuit 201 side disappears.

Therefore, in the event of a power failure or the like, if the power is restored before the potential on the control power supply circuit 206 side completely disappears, the order of potential establishment described above will be reversed, so The circuit 208 detects a voltage shortage on the converter circuit 201 side and continues the protection operation, resulting in an inconsistent operation. Then, in this case, the contact 209 and the discharge resistor 210 connected to the control power supply circuit 206 serve as an effective means for eliminating such a contradiction.

The operating state of the protection circuit 208 of the inverter device 200 (presence or absence of the protection operation and the reason for the operation) is taken into the pump control device 300 via the interface circuit 303. Further, the operation command (including the speed command) from the pump control device 300 is also given to the inverter control circuit 205 via the interface circuit 303, and the inverter device 200 supplies the AC power of the output frequency corresponding to the operation command to the terminal X. , Y, Z, and the motor 401,
Power 402.

Further, the detection value of the pressure detector 405 for detecting the discharge pressure of the pumps 411, 412 is also taken into the pump control device 300 via the interface circuit 303.

In the conventional example of the water supply device using this variable speed pump, after setting various operating conditions in the switch group 305 in the pump control device 300, by turning on a power switch and an operation start command switch (not shown), Pump operation control is started in accordance with a control program stored in the memory 302 in advance.

During operation, the pump controller 300
Controls the power supply switching circuit 330 as needed, and under normal conditions, by controlling the contacts 352, 354, power is supplied from the inverter device 200 to the motors 401, 402 for variable speed driving, and the pumps 411, 412 alternately act. Alternatively, water is supplied from both of them, and the discharge pressure detected by the pressure detector 405 is controlled so as to converge to a predetermined target value.

However, when the inverter device 200 is stopped for some reason, the pump control device 300
Keeps the contacts 352 and 354 of the power supply switching circuit 330 open, and this time controls the opening and closing of the contacts 351 and 353 so that the electric power from the commercial power supply 100 is supplied to the motors 401 and 402.
To drive the pump at a constant speed and supply water from the pumps 411 and 412 alternately or both.
The discharge pressure detected in 05 is controlled so as to converge to a predetermined target value.

[0024]

In the prior art, no consideration is given to the deterioration of the water supply performance when the inverter is stopped, and there is a problem that the water supply pressure fluctuates greatly and the operating cost increases. It was That is, when the inverter device stops, the pump is operated at a constant speed by the commercial power source, so it becomes difficult to follow the discharge pressure according to the change in the demand water amount, and the water supply pressure fluctuates greatly. In addition, since the pump is operated at full speed even when the load is light, there arises a problem that the operating power cost increases.

In addition, when the inverter device is stopped, it is required to promptly investigate the cause and restart the operation by the inverter device. Therefore, the inverter device issues an alarm and the water supply device Problems such as the maintenance manager being called up urgently will also occur.

It is an object of the present invention to provide a water supply device that is less likely to deteriorate the water supply performance even when the inverter device is stopped, and less likely to be stopped when the motor or pump is abnormal.

[0027]

The above object is to provide a plurality of inverter devices having a protection function, and a plurality of motors that are operated at variable speeds by power supply from these inverter devices,
A water supply device comprising a plurality of pumps respectively connected to these motors, and a pump control device for controlling the inverter device so that the discharge pressures of these pumps have a predetermined relationship. When the operation of the inverter device is stopped, restarting means for returning the stopped inverter device to an operating state, power supply switching connected between outputs of the plurality of inverter devices and inputs of the plurality of motors Means for restarting the stopped inverter device at least twice when the inverter device is stopped, and the power supply switching device outputs the output of the inverter device when the motor or pump is abnormal. This is achieved by switching to a normal motor.

[0028]

When the inverter device is stopped by its own protection function, the restarting device works to return the inverter device to the operating state again, and when the inverter device is restarted by this, the cause of protection of the inverter device is If the problem has been resolved, the inverter device will be operated again, and the probability that the inverter device will stop completely can be reduced.

Further, the power supply switching means works to switch the power supply of the inverter device to a normal motor when the motor or the pump fails, thereby reducing the probability that the water supply device will be completely stopped. be able to. Therefore, there is little risk that the water supply performance will deteriorate even when the inverter device is stopped, and there will be less risk that the water supply will be stopped even when the motor or pump is abnormal.

[0030]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A water supply device using a variable speed pump according to the present invention will be described in detail below with reference to the illustrated embodiments.
FIG. 1 includes two inverter devices 200 and 220,
Using two pumps 411 and 412 driven by two motors (induction motors) 401 and 402, the pump 41
This is an embodiment in which the present invention is applied to a water supply device in which water is supplied by controlling the discharge pressure to be constant by driving 1, 412 at a variable speed.

In FIG. 1, 100 is a commercial power supply, and the inverter devices 200 and 220 are supplied with three-phase AC power from the commercial power supply 100. Each inverter device 200, 2
20 is the same as the prior art in FIG. 5, and has the following configuration.

Commercial power supply 10 is supplied via terminals U, V, and W.
Converter circuits 201, 221 that receive three-phase AC power from 0 and convert this AC power into DC power. A transistor for reconverting the DC power converted by these converter circuits 201 and 221 into AC power.
Inverter circuit 20 composed of a bridge or the like
2, 222. Smoothing capacitors 203 and 22 for smoothing the DC power converted by the converter circuits 201 and 221.
3. Current detectors 204, 224 for detecting the value of current supplied to the inverter circuits 202, 222.

Inverter control circuits 205 and 225 that control the reconversion operation of the inverter circuits 202 and 222 based on an operation command (including a speed command) from the outside.

Inverter control circuits 205, 225
And a control power supply circuit 2 for supplying control power to other parts
06, 226.

Smoothing capacitors 207 and 227 connected to the output sides of the control power supply circuits 206 and 226. When a trouble occurs in continuing the operation of the inverter circuits 202 and 222, this is detected and the inverter circuit 2
02, 222 protection circuit 208 for stopping the re-conversion operation,
228. Terminals X, Y, Z for outputting variable frequency AC power of the inverter circuits 202, 222.

The inverter device 2 having such a configuration
Since 00 and 220 are well known as described above, a detailed description of their operation will be omitted. However, in case of caution, first, the control power supply circuits 206 and 226 will be described.
Receives an AC power from the commercial power supply 100 or a DC power from the converter circuits 201 and 221 and supplies necessary control power to each place in the inverter devices 200 and 220.

Further, the protection circuits 208 and 228 are provided with a power supply voltage to the converter circuits 201 and 221, a power supply voltage to the inverter circuits 202 and 222, or a power supply current, the temperature in the inverter circuits 202 and 222, the inverter control circuit 205, and the like. The control operation etc. in 225 are constantly monitored, and power failure,
When undervoltage, overvoltage, overcurrent, overheat, malfunction of control sequence, etc. are detected, the inverter control circuit 205,
225, or the inverter circuits 202, 222
It directly stops the reconversion operation of.

Next, reference numeral 300 denotes a pump control device, which serves to perform various controls so that the pressure of the supply water discharged from the pump has a predetermined fixed relationship.
The microcomputer 301 includes a central processing unit 301, a memory (including ROM and RAM) 302, an interface circuit 303, which are mutually connected by a data bus (including an address bus) 304. At the same time, it is configured by a power supply circuit, a clock generation circuit and the like which are not shown.

Then, in the ROM area of the memory 300,
As will be described in detail later, control programs for controlling the pump and managing the inverter device are stored in advance, and the RAM area is used to continue the arithmetic processing of the central processing unit 301. Required work area is secured.

In the interface circuit 303, an A / D converter for converting external analog data into digital data, a D / A converter for converting internal digital data into analog data, and a data transfer Latch circuits, transistor relay circuits for signal amplification, etc. are prepared as necessary. 305 is a switch group for performing initial setting of the pump control device 300,
It is connected to the interface circuit 303.

Reference numeral 400 denotes a water supply unit, which is provided with the motors 401 and 402 and the first and second pumps 411 and 412 connected to the motors 401 and 402, respectively, as described above. A water supply pipe 403 commonly connected to the discharge side via a check valve and a gate valve, a pressure tank 404 connected to the water supply pipe 403, a pressure detector 405, and the like.

Reference numeral 350 denotes a power supply switching circuit which is arranged between the inverter devices 200 and 220 and the water supply unit 400 and whose operation is controlled by an opening / closing command from the pump control device 300. The four contact points 351 to 354 are provided. With contact 35
1 is a motor 401 to the inverter device 200, contact 35
2, the motor 401 to the inverter device 220, the contact 35
3 is a motor 402 to the inverter device 200, contact 35
4 connects the motor 402 to the inverter device 220, respectively.

More detailed description will be given of 210,
Reference numeral 230 denotes a discharge resistor, which is connected to the outputs of the control power supply circuits 206 and 226 by closing the contacts 209 and 229 during the protection operation of the inverter devices 200 and 220, and discharges the electric charge remaining in the smoothing capacitors 207 and 227. Works to

The inverter devices 200 and 220 are usually
To guarantee the operation at power-on or during protection operation,
When the power is turned on, the potentials on the control power supply circuits 206 and 226 are established after the potentials on the output sides of the converter circuits 201 and 221 are established. During the protection operation, after the potentials on the converter circuits 201 and 221 disappear. Control power supply circuits 206, 2 so that the protection operation is guaranteed for a sufficiently long period.
It is configured to secure the potential on the 26 side.

Therefore, in the event of a power failure or the like, if the power is restored before the potentials on the control power supply circuits 206 and 226 side completely disappear, the order of potential establishment described above will be reversed. The protection circuits 208 and 228 detect a voltage shortage on the converter circuits 201 and 221 side and continue the protection operation, which causes an inconsistent operation. Then, in this case, the control power supply circuit 206,
Contact points 209 and 229 connected to 226 and discharge resistor 21
0 and 230 are effective means for resolving such a contradiction.

The operating states of the protection circuits 208, 228 of the inverter devices 200, 220 (presence or absence of the protection operation and the reason for the operation) are taken into the pump control device 300 via the interface circuit 303. Further, an operation command (including a speed command) from the pump control device 300 is also transmitted via the interface circuit 303 to the inverter control circuits 205, 2
25, the inverter devices 200 and 220 supply the AC power of the output frequency corresponding to the operation command to the terminal X,
Output through Y and Z to supply power to the motors 401 and 402.

Further, the detected value of the pressure detector 405 for detecting the discharge pressure of the pumps 411, 412 and the trip signal indicating the operating state of the thermal relays 355, 356 are stored in the pump controller 300 via the interface circuit 303. It is designed to be taken into.

Next, the operation of this embodiment will be described with reference to the flowchart of FIG. Also in this embodiment, as in the prior art, after setting various operating conditions in the switch group 305 in the pump control device 300, by turning on a power switch and an operation start command switch (not shown), the memory 302 is stored in advance. The operation control of the pump is started according to a predetermined control program stored in.

That is, prior to the operation of the switch group 305, the discharge target pressure H ₀ , the minimum operation speed N ₁ , and the maximum operation speed N _{3 are} set by the operator according to the configuration of the water supply section 400 or the operation requirements. , Speed change (increasing / decelerating) width Δ
Data such as N, restarting determination time T, and restarting frequency m are set.

Specifically, the maximum operating speed N ₃ is equal to the operating speed when operated by the commercial power supply 100, and the speed change width ΔN is such that the operating speeds of the pumps 411 and 412 are set in multiple stages and the discharge pressure H is different. The variation is selected to be sufficiently small, and the restart determination time T is set to be equal to or slightly longer than the normal startup time of the pumps 411 and 412. In this embodiment, the restarting determination time T is set to 20 seconds and the number of restarting operations m is set to 2 times.

In FIG. 2, when the operation of the pump control device 300 is started after the above preparation, step 501
Then, first, each data set in the switch group 305 is read through the interface circuit 303 and stored in each address in the RAM area of the memory 300.

At the same time, the pump control device 300 receives, for example, the first pump 41 via the interface circuit 303.
When the operation of No. 1 (or the second pump 412) is performed in advance, the process required to close the contact 352 in the power supply switching circuit 350 in advance is performed. In the next step 502,
The discharge pressure H on the discharge side of the pumps 411, 412 is fetched from the pressure detector 405, and in step 503, the inverter devices 200, 220 are respectively fed from the protection circuits 208, 228 via the inverter control circuits 205, 225 or directly. The operating states are sequentially fetched and stored in the work areas secured in the RAM area of the memory 300 (not shown).

At the next step 504, the step 5 is executed.
The operation state of the inverter devices 200 and 220 fetched in 03 is evaluated, and if this is in normal operation, the next step 505 is executed, while the protection circuits 208 and 228 act to protect the inverter devices 200 and 220. If it is below, the re-operation process of the inverter devices 200 and 220 in step 510 is performed.

In step 505, the discharge pressure H taken in in step 504 is evaluated. If the discharge pressure H does not reach the target pressure H ₀ , the speed increasing process in step 506 is performed, and the discharge pressure H exceeds the target pressure H _0. If yes, step 50
The deceleration process 8 is performed. That is, step 506
In the speed increasing process, the current operating speed (target value) of the pump 411 is updated so that the operating speed of the pump 411 is increased by the speed change width ΔN within the range of the maximum operating speed N ₃ , and the target value is set to this target value. Accordingly, a new operation command is transmitted to the inverter devices 200 and 220 via the interface circuit 303. Therefore, the inverter devices 200 and 220 change the output frequency based on the new operation command, and perform the speed-up operation of the motor 401 (pump 411) and the motor 402 (pump 412). As a result, at this time, the discharge pressure H of the pumps 411 and 412 rises.

On the contrary, if it is judged in step 505 that the discharge pressure H exceeds the target pressure H ₀ , step 50
In 8 the operating speed of the pumps 411, 412 is the minimum operating speed N
The current operating speed (target value) of the pumps 411, 412 is updated so as to reduce the speed change width ΔN within the range of ₁ , and a new operation command is issued according to the target value.
0, 220. Therefore, the inverter devices 200 and 220 are controlled by the motor 40 based on the new operation command.
The deceleration operation of 1 and 402 is performed. As a result, at this time, the discharge pressure H of the pumps 411 and 412 drops. When it is evaluated in step 505 that the discharge pressure H and the target pressure H ₀ are equal, the process directly proceeds to step 511.

Therefore, after execution of step 506 or 508, in order to absorb the control delay of the water supply section 400, if the control is returned to the processing of step 502 after some waiting time, the control of step 502 and subsequent steps is performed again. The operation is repeated, and as a result, the discharge pressure constant control according to the water supply amount Q is obtained along the characteristic curve shown in FIG.

On the other hand, although not shown in detail, in the case of performing the constant end pressure control, the above steps 506 and 50 are performed.
After executing the acceleration / deceleration processing of 8, the following step 507,
In 509, the target pressures corresponding to the updated current operating speed (target value) obtained on the water supply characteristic (load curve) of the water supply unit 400 may be respectively updated and stored.

At the next step 511, the trip signals of the thermal relays 355 and 356, and the pressure detector 405.
It is determined whether the motors 401 and 402 and the pumps 411 and 412 are operating normally based on the pressure signal of. That is, the thermal relays 355 and 356 are connected to the motor 40.
The pressure detector 4 detects the abnormalities due to the overcurrent of 1, 402.
Reference numeral 05 detects an abnormal decrease in the discharge pressure of the pumps 411 and 412.

If it is determined in step 511 that there is no abnormality, thereafter, as described above, the process returns to step 502 and the control operation from step 502 onward is repeated.

If an abnormality is detected, first, at step 512, the inverter devices 200, 2
After the speed command to 20 is reduced to the starting speed, a switching signal is sent to the power supply switching circuit 350 in step 513, and among the motors 401 and 402, the motor not currently driven, that is, the motor in which no abnormality is detected, Inverter device 2
The power supply from 00 and 220 is switched.

Here, the role of step 512 is to give a soft start function to accelerate the stopped motor from the starting speed, that is, approximately 0 rpm.
The point is to suppress the starting current and prevent malfunction of the inverter devices 200 and 220 and circuit breakers in power distribution equipment.
After step 513, as described above, step 50
The control operation of 2 or less is repeated.

Next, the details of the re-operation process of step 510 will be described with reference to FIG. 3, assuming that the inverter device 200 is out of order. In FIG. 3, step 51
1, the pump control device 300 has the interface circuit 3
An operation command for cutting off the output of the inverter device 200 is issued via 03.

At the next step 512, an operation command for resetting the protection operation of the protection circuit 208 in the inverter device 200 is issued. Further, in step 513, a control operation for closing the contact 209 is performed via the interface circuit 303. By closing the contact 209, the electric charge of the control power supply circuit 206 is consumed via the discharge resistor 210. In this way a series of steps 511-51
By 3, the preparation for re-operation of the inverter device 200 is completed.

Further, in step 514, the pump control device 300 sends a command to the inverter device 200 via the interface circuit 303 to restart the inverter device 200.
(Eg minimum operating speed N ₁ ) is emitted. As a result, the inverter device 200 increases the frequency of the AC power output from the terminals X, Y, Z to a value corresponding to the minimum operating speed N ₁ .

In step 515, the elapsed time since the operation command was generated in step 514 is evaluated, and when it reaches the predetermined re-operation determination time T, the process proceeds to the next step 516, where the inverter device is set. Evaluate 200 operating conditions. That is, in this step 516, the previous step 50 is executed via the interface circuit 303.
3, the operation signal of the protection circuit 208 is fetched, the operation state of the protection circuit 208 is evaluated, and when the protection operation has not occurred, that is, when the restart of the inverter device 200 is successful, the next step After the value n of the re-operation counter stored in the memory address is cleared to zero in 517, the control operation after step 502 described above with reference to FIG. 2 is taken over.

If the restart of the inverter device 200 has failed in step 516 and the protection operation of the protection circuit 208 has occurred, the number of re-operations, that is, the memory address stored in advance is stored in the next step 518. The number m of restarts being performed and the value n of the restart counter stored in another memory address are compared and evaluated.

If the value n of the re-operation counter has not reached the number m of re-operations in this step 518, the value n of the re-operation counter is incremented, and then the control operation from step 511 onward is executed again. And step 518
If it is determined that the value n of the re-operation counter has reached the number of re-operations m, it is difficult to restart the inverter device 200. Therefore, the following step 519 is executed and the motor 401 Is a normal inverter device 220
Switch to. That is, in step 519, the pump control device 300 opens the contact 351 of the power supply switching circuit 350 via the interface circuit 303, and the contact 352.
By closing the
It is switched to the variable speed operation by 20.

Although not shown in detail in step 519, the pump control device 300 performs the operation preparation operation of the inverter devices 200 and 220 as described in steps 511 to 513 here. , Issues a necessary alarm via the interface circuit 303,
It is configured to make an emergency call to the maintenance manager of the water supply device.

Thus, according to this embodiment, step 5
By repeating the control operation including 16, 518 and the like, restarting of the inverter devices 200 and 220 is tried within the number of times defined as the number of re-operations m, and when the starting of the inverter devices 200 and 220 is successful, The variable speed operation of the pump 411 by the normal inverter devices 200 and 220 is continued as it is, and it is possible to suppress the occurrence of water interruption.

In the discharging process of the control power supply circuits 206 and 226 in step 513 of FIG.
Depending on the selection conditions such as the resistance value of 0 or 230, it takes several seconds, so the operation command in the next step 514 is to issue the operation command after the discharge time, that is, for a fixed time set in advance longer than the discharge time, for example, about It is necessary to set it to be emitted after 3 seconds.

Further, in this embodiment, the operation command (speed command) issued in step 514 is set to the minimum operation speed N ₁ , but the value of this speed command is predetermined to be equal to or more than the maximum operation speed N _1. The value may be set to a value immediately before the protection operation of the inverter devices 200 and 220 occurs.

Further, in the above embodiment, the first pump 4
11 was operated at a variable speed (or constant speed). This is, as is known, a parallel operation of a constant speed pump and a variable speed pump by a plurality of pumps or a prior operation by a switching operation of a power supply switching circuit 350. The pumps may be replaced, and the spare machine may be freely selected.

By the way, in the above embodiment, when the inverter devices 200 and 220 are in the protection state, the number m of re-operations to continuously try the re-operations is set as a predetermined constant value. m can be set as a variable amount that changes according to the water supply state (operating state). That is, in the embodiment, as shown in FIG. 1, since the pressure tank 404 is provided, the discharge pressure H may immediately decrease in a range where the water supply amount (demand water amount) is small even if the pump operation is stopped. Inverter device 200, 2
There is some leeway to do 20 restarts.

Therefore, in this case, the number of restarts m can be set to a larger value than in the case where there is no pressure tank.
Furthermore, the possibility of continuing water supply can be increased.

[0075]

According to the present invention, when the inverter device is stopped due to its own protection function, a restart command is given to the inverter device. Therefore, if the cause of the abnormality of the inverter device is eliminated at this point. In this case, the inverter device will be operated again, and the probability that the inverter device will completely stop can be reduced. Also,
When the electric motor or pump fails, the output of the inverter device is switched to a normal electric motor, so the probability that the water supply operation will stop completely can be reduced,
Therefore, it is possible to easily provide a highly reliable water supply device that is less likely to run out of water.

[Brief description of drawings]

FIG. 1 is a block diagram showing an embodiment of a water supply device using a variable speed pump according to the present invention.

FIG. 2 is a flow chart for explaining a basic driving operation in one embodiment of the present invention.

FIG. 3 is a flowchart for explaining a restarting operation of the inverter device according to the embodiment of the present invention.

FIG. 4 is a characteristic diagram for explaining a water supply operation in one embodiment of the present invention.

FIG. 5 is a block diagram showing a conventional example of a water supply device using a variable speed pump.

[Explanation of symbols]

 100 Commercial power source 200, 220 Inverter device 201, 221 Converter circuit 202, 222 Inverter circuit 205, 225 Inverter control circuit 206, 226 Control power circuit 208, 228 Protection circuit 209, 229 Contact 210, 230 Discharge resistance 300 Hump control device 301 Central Processor 302 Memory 303 Interface circuit 305, 306 Switch group 350 Power supply switching circuit 400 Water supply section 401, 402 Motor 404 Pressure tank 405 Pressure detector 411, 412 Pump

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Koji Ohno 7-1, 1-1 Higashi Narashino, Narashino City, Chiba Prefecture, Hitachi Industrial Equipment Division

Claims (3)

[Claims] 1. A plurality of inverter devices having a protection function, a plurality of electric motors that operate at a variable speed by power supply from these inverter devices, and a plurality of pumps that are respectively connected to these electric motors. In a water supply device including a pump control device that controls the inverter device so that the discharge pressure of the pump has a predetermined relationship, when the operation of the inverter device is stopped, the stopped inverter device is operated. A restarting means for returning to the state, a power supply switching means connected between the outputs of the plurality of inverter devices and the inputs of the plurality of electric motors are provided, and the restarting means stops the inverter device. At this time, the stop inverter device is repeatedly activated at least twice, and the power source switching unit is configured to: Water supply apparatus using a variable speed pump which is characterized by being configured to switch the output of the serial inverter apparatus to a normal motor. 2. The invention according to claim 1, wherein the inverter device is provided with a soft start means, and the soft start means activates the electric motor when the inverter device is switched by the power source switching means. A water supply device that uses a variable speed pump. 3. The invention according to claim 1 or 2, wherein the abnormality of the electric motor is due to operation of a thermal relay overcurrent protection function connected to each electric motor, and the abnormality of the pump is 2. The water supply device using a variable speed pump according to claim 1, wherein the water supply device is configured so as to be activated by a pressure abnormal drop detection function of a pressure switch attached to the discharge side pipe.