JPS6138183A - Variable speed water supply device - Google Patents

Abstract

PURPOSE:To enable automatic start upon affirmative answer by comparing the operating condition under stoppage of pump due to inverter trip with predetermined conditions for safety operation. CONSTITUTION:Conditions for safety operation such as operating current, operating frequency, supply water pressure, etc. of motor 5 as pump system 6 to be determined from the rating of said pump system 6 are previously stored in a memory of computer of controller 4. The controller 4 will operate the end pressure of supply water on the basis of pressure signal SW from a pressure sensor 11 and frequency command signal Sf while also provided with the input current I of the motor 5 indicated on an ammeter 13. In the controller 4, CPU will compare the operating conditions under tripping with the conditions for safety operation to decide the cause of inverter 3 trip thus to decide the ability of starting operation automatically and to enable starting automatically if the answer is affirmative resulting in prevension of interruption of water supply due to unknown cause.

Description

Detailed Description of the Invention [Objective of the Invention] "Industrial Application Field" This invention is a method for controlling supply water pressure or terminal pressure using a variable speed electric motor whose speed is controlled by an inverter and a pump driven by the variable speed electric motor. This invention relates to a variable speed water supply device that supplies water at a constant or constant flow rate.

``Prior art'' In general, inverters that variablely adjust induction motors or synchronous motors have a control system to protect the inverter when it becomes uncontrollable due to load on the inverter due to sudden changes in the system (referred to as inverter trip). It is designed to output a signal (called an inverter trip signal) that indicates a failure.

Variable-speed equipment equipped with an electric motor whose speed is controlled by an inverter, such as variable-speed water supply equipment that changes the rotational speed of the pump to maintain a constant water supply pressure, stops the equipment in response to an inverter trip signal. It is common to do so.

In general, the inverter that controls the speed of a general-purpose motor is subject to a rise in inverter output current due to a sudden increase in load, ■instantaneous inrush current due to a short circuit or ground fault on the load side, ■current generated during single-phase operation due to an open phase on the load side. Unbalance, ■Load-side overcurrent and undervoltage due to input power supply voltage drop, ■Voltage breakdown due to input power supply voltage increase, ■Overcurrent generated due to phase difference between load rotation phase and inverter operation phase at restarting after instantaneous power failure, etc. In contrast, the inverter has a circuit that prevents damage to the inverter power section, but there are cases where the inverter trips due to such transient phenomenon factors, and cases where the inverter trips temporarily due to factors similar to the above phenomenon.

``Problem to be solved by the invention'' In a variable speed water supply system, if the main inverter stops, all functions will stop, or provisional control such as driving the pump with other commercial power source will be required. Therefore, the main purpose of constant discharge pressure control, constant estimated terminal pressure control, constant flow rate control, etc. cannot be achieved. In addition, when an inverter trips, it is necessary to perform some kind of operation to release the trip, but it takes a lot of effort to estimate and reproduce the load condition in order to eliminate the cause of the inverter trip again. It required a lot of time and effort.

The present invention provides a variable speed water supply device equipped with a control device that has a function of determining the cause of an inverter trip and determining whether or not to restart the inverter. The purpose is to provide water supply equipment.

[Structure of the invention]

"Means and actions for solving problems" The control device of the variable speed water supply system is equipped with a sensor that takes out data such as the input current, input frequency, and water supply pressure of the electric motor that drives the pump. A device for storing data is provided, and when an inverter trip occurs, the data immediately before the inverter trip occurs is compared with a predetermined condition stored in the storage device that makes it dangerous to continue operating the pump device. If it is safe, restart the system and start supplying water. If it is dangerous, the motor should be stopped.

"Example" FIG. 1 is a block diagram of an embodiment of the invention.

Power is supplied from the power source 1 to the inverter 3 via the switch controller. A frequency command signal 8f is input from the control device Hiroshi to the inverter 3, and the power at the frequency of the frequency command signal 8f is output from the inverter 3 to generate an induction motor or a synchronous motor (hereinafter simply referred to as a type of motor that can be controlled by an inverter). It is designed to energize an electric motor (5). Electric motor 3 drives pump 6.

The inverter 3 is configured to output an inverter trip signal 8i when the motor 3 cannot be controlled by the inverter 3, and the inverter 3 is configured to input the inverter trip signal B1 to the control device.

Water sucked from the water tank through the suction pipe t is pressurized by the pump 6 and discharged to the discharge piping.

The discharge pressure of the pump is detected by a pressure sensor provided in the discharge pipe 91, and the discharge pressure signal 8v is sent to the pump controller. The pump control device DA uses the relationship between the discharge pressure signal BV detected by the pressure sensor ii and the rotational speed of the pump base to output a frequency command signal Bf with a constant terminal pressure to the inverter 3, and the inverter 3 outputs a frequency command signal Bf with a constant terminal pressure to the inverter 3. - converts the frequency of the commercial power supply l input through the terminal, outputs power with a frequency matching the frequency command signal Bt, changes the speed of the electric motor 5, and converts the rotational speed of the pump group to perform constant terminal pressure control. conduct. Alternatively, for example, when piping resistance is low, constant discharge pressure control is performed. Alternatively, the discharge piping is equipped with a flow meter, and the water supply end pressure is controlled to be constant using the flow meter signal and the detected value of the pressure sensor.

Alternatively, a flow rate signal from a flow meter (not shown) provided in the discharge piping is input to the control device G to control the frequency command signal Sf, and the speed of the electric motor S is changed through the inverter 3 to perform constant flow rate control.

When an inverter trip occurs, the control device turns off the switch λ, turns on the switch λ, and temporarily operates the electric motor 3 using commercial power.

The control device is equipped with a microcomputer, and the storage device of the microcomputer stores the pressure signal Sv and the frequency command signal Sf, or if it is equipped with a flow meter, the water supply end pressure determined from the water supply amount and the frequency command signal Sf. P
s, the frequency command signal Sf, that is, the operating frequency, when the control device l performs, for example, constant terminal water supply pressure control, the operating current signal indicated by the ammeter 73 that detects the input current of the motor 3, the operating state, e.g. In the case of parallel operation pump equipment, automatic operation with only one inverter-driven pump, etc. Data immediately before an inverter trip occurs is fixed in the storage device when an inverter trip occurs, and at the same time, the date of occurrence of the inverter trip is stored in the storage device. be remembered.

On the other hand, the storage device stores predetermined rated specifications of the variable speed water supply device in inverter-driven pump operation. For example, the rating of motor 3 is the maximum frequency of supplied power &OHz.

Voltage aθOV, output 3. 'lK, W, and maximum input current/da, 3A. Electric motor in this case! is the input current/
'IJA is stored in the storage device together with an instruction for determining whether data to be input later is equal to or greater than /lI,jA for the input current input.

Similarly, the maximum operating frequency of 40 Hz is stored together with an instruction ◆ for determining whether the operating frequency sr input later is AOHz.

Load equipment is water supply pressure 3T14/ex2 constant, flow rate 2jt
O1/rn is a 30-story apartment building with 30 apartments, and along with this self-supplied water pressure j Kp/cm, a judgment order to determine whether the water supply pressure is below 3-2 is stored, which will be input later. Such judgment data is determined as the planned value of the pump device.

When an inverter trip occurs, the date of occurrence is stored in the storage device. Inverter) In the state where the IJ bump occurs, the water supply pressure/Kf/crn2 and the input current of the motor 3 indicated by the ammeter 13/7A.

Assume that the operating frequency is 5f40H2.

In the control device, the pressure signal SW from the pressure sensor l/ and the frequency command signal 8f are combined to determine the terminal water supply pressure/Ky7'c.
rn2 has been calculated, and the input current I of the motor 3 indicated by the ammeter 13 is input to the control device t. In the control device, the central processing unit performs the determinations shown in the table below.

Input data Judgment data Judgment current Engineering /'7k /lJA Yes Frequency Sf A OHz MAX 40H2 High water supply pressure / Kg/crrt” Yes Operating status Inverter Inverter Yes Electrician is rated current / IIJA, the judgment is ``Yes'' as to whether it is dangerous, ``Yes'' as to whether the frequency at is the maximum frequency AOHZ, and the water supply pressure is lower than the rated water supply pressure 3 (-). As for whether the inverter is running, the answer is yes, and the answer is yes, as for whether the inverter is being driven.

Since both of them are positive for the judgment data, this inverter trip is determined to be in a dangerous state and a fault is displayed externally, and if it is determined that it is not in a dangerous state, a restart is possible to the variable speed water supply system. This system sends an inverter tachometer helicopter reset signal Sr to automatically reset the water and supply water again.

On the other hand, the input data when an inverter trips like this is printed out along with the date and time of occurrence, and by checking the data later, for example, it can be determined that the cause is overcurrent due to overspec such as washing the car early on Sunday morning, washing the car, watering the garden, etc. It is assumed that.

In the embodiment, a case has been described in which one inverter-driven variable speed motor is used as the pump driving means, but the same applies to a case where a plurality of variable speed motors are used, or a case where a plurality of variable speed motors and a fixed speed motor are respectively provided.

〔Effect of the invention〕

The present invention is a variable speed water supply system equipped with a pump driven by an electric motor whose speed is controlled by an inverter, and is equipped with an abnormality detection circuit to protect the inverter equipment. The conditions are stored in memory, and when the abnormality detection circuit to protect the inverter equipment is activated, the operating conditions for the pump device are compared with the pre-stored safe operating conditions for the pump device, and the system can resume operation. Because the variable-speed water supply system is equipped with a control device that determines whether the pump is in a There is no need to spend time and effort investigating the cause of the IJ bulge, and the system can be started automatically if it is determined that it can be restarted, thereby avoiding water outages for unknown reasons.

[Brief explanation of drawings]

FIG. 1 is a flow sheet of an embodiment of the present invention. l...Power supply λ/C switch 3II/Inverter tag...Control device!・＠Electric motor ６．・Pump ri・・Water tank l・・Suction pipe ta・・Discharge piping //−・Pressure sensor /, i・・Switch /3・・Ammeter. Patent applicant Ebara Corporation Ebara Kaisan Corporation

Claims (1)

[Claims] 1. In a variable speed water supply system equipped with a pump driven by an electric motor whose speed is controlled by an inverter and equipped with an abnormality detection circuit to protect the inverter equipment, the pump is determined in advance from the rating of the pump device. The safe operating conditions for the pump device are stored in memory, and when the abnormality detection circuit for protecting the inverter equipment operates, the operating conditions for the pump device are compared with the pre-stored safe operating conditions for the pump device. A variable speed water supply system equipped with a control device that determines whether it is ready for operation again. 2. The safe operating conditions to be compared are the rated operating conditions, and include the operating current of the motor, the operating frequency, the water supply pressure, and the classification of which pump drive motor is in automatic operation. Variable speed water supply device as described. 3. The variable speed water supply device according to claim 1, wherein the operating conditions to be compared are operating conditions in the same operation before the current operation of the abnormality detection circuit for the inverter.