JPS5896190A - Control device for pump operation - Google Patents

Abstract

PURPOSE:To simplify the configuration of a pumping control system by using only a pressure signal and a rate-of-flow signal as analog input and solely a speed signal as analog output and thereby providing possiblility of treatment of all signals by the software in a sequencer. CONSTITUTION:A sequencer 19 is directly fed with digital signals such as contact input signals from switches, buttons, etc. and a signal from the electrode 15 as well as analog signals from a pressure signal transmitter 7 and a rate-of-flow transducer 9, and carries out conversion of analog signals into digital signals to treat all signals there in the form of digital signal. Thus there are only pressure signal and rate-of-flow signal as analog input and solely speed signal as analog output, and all signals can be treated by the software in the sequencer 19, so that analog instruments used here are only the pressure signal transmitter 7 and rate-of-flow transducer 9, that will assure a simplifield configuration for the system.

Description

[Detailed description of the invention] The invention is powered by a variable speed electric motor.

This relates to a pump operation control device that automatically controls the discharge pressure to a constant level or the terminal pressure to a constant level, and is related to a pump operation control device that automatically controls the discharge pressure to a constant level or the terminal pressure to a constant level. f. This invention relates to a new system configuration of a pump operation control device that is an inexpensive device that is used in small and medium-sized water supply facilities such as apartment buildings, pillboxes, and factories.

When water is supplied by driving a spiral pump or a turbine pump, a variable speed electric motor is generally used as the pump drive motor to automatically control the discharge pressure at a constant level or the terminal pressure at a constant level. FIG. 1 is a characteristic diagram showing the pump characteristics, and shows the load flow rate Q and the discharge pressure, that is, the head T, as parameters such as the number of revolutions N of the pump. In this Figure 1.

The curve lIn is a line characteristic curve, which shows the required pressure H at the pump discharge part in response to a change in flow rate when constant control of the terminal pressure is performed.

As is clear from this figure, when the pump is rotated at a constant speed at a predetermined number of revolutions, the discharge pressure T exhibits the following characteristics with respect to changes in the load flow rate Q. Therefore, when the pump is subjected to constant discharge pressure control or constant terminal pressure control, efficient operating characteristics can be obtained, and there is an advantage that water can be delivered at an optimal pressure in response to changes in load flow rate. In order to obtain such efficient operating characteristics, it is generally as shown in FIG.

Set the desired discharge pressure surface and straighten! (There are methods such as constant control of the discharge pressure, which controls the rotation speed of the pump according to the load flow rate according to 3A, and constant control of the terminal pressure, which controls the rotation speed according to the 9-curve line.To perform these pressure controls, In addition to detecting the pump discharge pressure and load flow rate, it is also necessary to perform a comparison calculation between the desired discharge pressure setting value and the detected pump discharge pressure, and a function calculation to calculate the line loss from the detected flow rate value. In order to control the rotation speed, an output conversion device for the variable speed motor that drives the pump to the speed control device, a stabilization circuit to keep the automatic control system stable, etc. were required.

Conventionally, there has been a system configuration shown in FIG. 2 as an operation control device for this type of pump. In the figure, (ri is a water supply pump, (2) is a variable speed electric motor for driving the pump (11), and the speed is changed by a speed control device +31K. (41 is a water tank, (5) and (6) are It is a water transmission pipe, and when the water in the water receiving tank (4) is pumped up by the pump (1), the water is supplied to the customer through the water transmission pipe (51, +61).There is a pump in the middle of this water transmission pipe (5). A pressure transmitter (7) for detecting the pressure of the +11 outlet.

Between the water transmission pipe (5) and the water transmission pipe (6) to the customer, there is a flow rate detection device (flow meter) (8) that detects the load flow rate, and a flow meter converter (8) that converts the detected flow rate value into an electrical signal. 9) is installed and used as an input for automatic driving control. Alternatively, it is a pressure regulator, and when the desired pressure corresponding to the discharge pressure surface in Figure 1 is set, the signals from the pressure setting device and the pressure transmitter (7) are compared and calculated, and the detected pressure is calculated against the set pressure. If the detected pressure is smaller than the set pressure, a speed increase command is given to the pump, and conversely, if the detected pressure is larger than the set pressure, a speed control device (31) of the variable speed motor (2) is used to give a speed reduction command to the pump. It has a function to output commands. It is also possible to set the proportional band (FB) and integral time element (T) for stable and optimal control of the automatic control system. aη is the pressure controller section 0 is a flow rate setting device.

This is a contact output setting for determining the magnitude of flow rate when controlling a plurality of pumps (not shown). 0
is a function calculator, and in the case of constant terminal pressure control, it is a calculator for calculating the pipe line characteristic 5 shown in Fig. 1 for the load flow rate Q, and its output is the discharge pressure of the pressure regulator a1. The set pressure is corrected by adding and subtracting the value of the setter 0υ and the a field of the arithmetic unit. a4 is an operation control circuit, which is a relay circuit that configures switching between automatic and manual operation of the pump, a pump switching circuit when selecting a specific pump from among multiple pumps, and a backup circuit in the event of a failure. .

(to) is an electrode for detecting the water level in the water tank (41), and is converted into a relay contact by the floatless switch unit (Le).

It is used as an interlock for the pump operation circuit in the operation control circuit a4.

A conventional pump operation control device that drives a variable speed electric motor and automatically controls constant discharge pressure or constant terminal pressure has the above configuration. Total (8).

(9) In order to convert the electric signal into an optimal speed control signal, a pressure regulator part and a function calculator part (1 m long, arithmetic part part) are used.

Many complex analog devices such as the converter (lη) were used, and since the circuits between these circuits were analog weak current circuits of several IQHIA, careful wiring was required. Conventionally, K was constructed with a relay circuit, but in order to obtain a wide variety of circuit configurations to satisfy the diverse demands of customers, K had the problem of being narrow and requiring many components. .

It is an object of the present invention to provide a pump operation control device that eliminates the drawbacks of the complicated conventional circuit configuration as described above and can achieve the above-mentioned functions with a simpler configuration and with high accuracy.

Hereinafter, one embodiment of the device of the present invention will be described with reference to rotation pressure. FIG. 3 shows an embodiment of this invention.

In the figure (11 is the water supply pump, (2) is the variable speed electric motor, (3 is
1 is the speed control device, (4) is the water tank, (51, +61
is a water pipe.

(7) is a pressure transmitter, (8) is a flow meter, and (9) is a flow rate converter.

α9 is an electrode for detecting the water level in the water tank (4), as
indicates a programmable sequence controller (hereinafter referred to as a sequencer). In addition, contact input signals such as switches and push buttons and signals from electrodes (C) are directly input to the sequencer H as digital signals, and the pressure transmitter (
7) Alternatively, an analog signal from the flow rate converter (9) is also input, and the analog signal is converted into a digital signal in the sequencer a9, and all signals are treated as digital signals in the sequencer a9. In addition, the sequencer l executes the processing described later, but after completing this processing, it also outputs digital contact output signals for starting and stopping multiple pump motors (not shown), and performs speed control. It has a function of converting the analog speed output to the speed control device (31) from a digital signal to an analog signal within the sequencer and outputting it in accordance with the signal level of the speed control device (3). 1 is a functional block diagram showing an example of the function, and here we will explain the case where constant terminal pressure control is performed.Here, first, we will calculate the piping loss HB at the arbitrary load flow rate Q point shown in FIG. )
, (calculated as a function of the value (flow rate Q) detected in step 91. That is,

The rated flow rate of the pump 5, the desired pressure node, the value of the rated head surface of the pump, and the detected flow rate value are calculated by a piping loss calculation circuit to obtain the piping loss Bi. Thereafter, the required pump pressure HO at an arbitrary flow rate QK is obtained by adding together the piping loss surface and the desired pressure surface in the pump required pressure calculation circuit. Next, in the pressure adjustment signal calculation circuit, the detected pressure P detected by the pressure transmitter (7) is compared with the pump required pressure surface, and a proportional band FB and an integral time 7 corresponding to the function of the conventional pressure regulator aυ are determined. After running a functional sequencer a field, the pump minimum speed VMII
Calculate the speed output value by taking J into account.

Converts the optimal speed output value from a digital signal to an analog signal, taking into account the operating conditions, such as the manual-automatic operation switching circuit, pump operation stoppage, and special conditions in a transient state, etc.
The speed output signal is directly input from the sequencer 0 to the speed control device (31).

In the above embodiment, a case was explained in which the terminal pressure is controlled at a constant level, but constant pressure control or other control methods may be adopted and the same effects as in the above embodiment can be obtained.

As described above, according to the device of the present invention, the analog input signal is a pressure signal or a flow rate signal, and the analog output signal is only a speed signal.

Since all signals were configured to be processed by software within the sequencer, the only analog instruments were the pressure transmitter, flowmeter, and their converters.

All operation control circuits that vary depending on the customer's specifications can be processed within the sequencer, making the system configuration extremely simple and allowing the equipment to be supplied at low cost. It is highly effective as an operation control device.

[Brief explanation of drawings]

FIG. 1 is a characteristic diagram of the pump, and FIG. 2 is a diagram showing the configuration of a conventional pump operating system. FIG. 4 is a functional block diagram of a sequencer according to an embodiment of the present invention. 111... Water supply pump, (2)... Variable speed electric motor, a
s...Programmable sequence controller. Note that in the figures, the same reference numerals indicate the same parts. Agent Makoto Kuzuno - Figure 1 1 Table (Q) Figure 2 Figure 3 ff141! 1 Procedural amendment (voluntary) February 15, 1981 2, Name of invention Pump O rolling control device 3, Relationship with the case of the person making the amendment To the representative of the patent applicant, Hitoshi Katayama Part 4, Agent (1) Column for detailed explanation of the invention in the specification (2) Drawing 6, Contents of the amendment (1) Akira Tsunabechu , page 2, line 19, K "number of rotations N" is corrected to "number of rotations N." (2) In the 6th and 7th lines of page 3, the statement ``T stands for downward force'' is corrected to read ``rTti drooping characteristic.'' (3) Correct the drawing No. 4 according to the attached sheet ◎That's all

Claims (1)

[Claims] An operation control device for a pump driven by a variable speed electric motor whose speed is controlled by a speed control device, comprising: a pressure transmitter that detects the discharge pressure of the pump and outputs a signal; a flow rate detection device that detects the flow rate from the pump; A flow rate converter converts the flow rate detected by the flow rate detection device into an electric signal, and calculates the electric signal from the flow rate converter, the rated flow value and rated head value signal of the pump, and the desired discharge pressure signal, and calculates the desired discharge pressure signal for piping. a piping loss calculation circuit that outputs a loss value, a circuit that calculates the required pressure of the pump by adding the piping loss value from the piping loss calculation circuit and the desired discharge pressure signal, and a circuit that calculates the required pressure of the pump, and and a pressure adjustment signal calculation circuit that calculates the detection signal from the pressure transmitter and outputs a pressure adjustment signal, and adjusts the speed according to the output signal from the pressure adjustment signal calculation circuit of the sequencer. A pump operation control device characterized by driving a control device.