JPS61224014A - Forced feeding water supply device - Google Patents

Abstract

PURPOSE:To simplify constitution and quicken clearing up of the cause and restoration when pressure drop occurred, by operating a pump once by commercial power source driving and discriminating the cause of pressure drop from the change of pressure at this time. CONSTITUTION:When pressure drop occurred during operation of a pump 2, a constant speed switching device operates to open a switch 7 for variable speed operation and close a switch 8 for constant speed operation and drives an electric motor 1 by commercial power source, that is operates and controls a pump 2 at maximum speed. After the time of constant speed operation, process pressure PP and pressure drop warming pressure PL are compared by a comparator, and if PP>PL, restored to variable speed operation. When PP<PL after switching to constant speed operation, a pressure drop warning is outputted from a pressure drop warning device, and the pump 2 is stopped. When pressure drop occurred again within a set time after returning to variable speed operation by a returning device, a pressure drop warning is outputted and the pump 2 is topped as it is the second time.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a pressurized water supply device that operates a pump at variable speed to supply water under pressure.

[Prior Art] - Fig. 3 shows a conventional device, which constitutes a control system that controls the main piping around the pump and the rotation speed of the pump to control the pressure. In the figure, (1) is an electric motor capable of variable speed operation that drives the pump, and (2) is an electric motor (a) that drives the pump.
The pump (1) rotates in response to the driving force, and the pipe (3) distributes the water pressurized by the pump (2) to the destination, and the pressure in the pipe is called process pressure. (4) is a pressure transmitter that converts the process pressure in piping (3) into an electrical signal such as 4-20 [mA], and (5) is a pressure transmitter (after comparing the 0 signal and the set pressure signal). , a pressure regulator that performs automatic control using all or a combination of proportional control, integral control, and differential control, and outputs the result as a manipulated variable; (8) is the power required for the variable speed electric motor (1); (power supply)
This is a variable speed control device that supplies variable voltage and variable frequency inverters, primary voltage control motor control equipment, etc.

Therefore, (7) is a switch for variable speed operation that opens and closes the output of the variable speed control device (6), and (8) is a switch for stopping and bypassing the variable speed control device (6) to drive the electric motor a (1). Switch for constant speed operation, (9) is a controller that commands the opening and closing of switches (7) and (8), and (10) is a controller that supplies power from switches (7) and (8) to motor (1). Supply wiring, (11) is the output signal of the pressure transmitter (4), (12) is the set pressure PL of the pressure drop alarm, and is an electrical signal at the same level as the output signal (11), (13) is the signal ( (14) is a comparator that compares signal (11) and (12); (14) is an alarm circuit that issues an alarm after a set time limit and performs controls such as stopping the pump when signal (11) is smaller than signal (12); (15) ) is the power supply for this device.

In the above configuration, the constant discharge pressure control adjusts the rotational speed of the pump (2) so that the pressure in the piping (3) section to which the pressure transmitter (4) is attached remains constant even if the flow rate changes. .

Now, suppose that the set pressure and the pressure detected by the pressure transmitter (4) are the same, and the pump (2) is operating at a certain rotation speed.

After that, when the used flow rate increases, the pressure received by the pressure transmitter (4) decreases, so an electric signal (1
1) also decreases, and the pressure controller (5) performs proportional control (P),
After performing integral control (I), differential control (D), etc., the output signal is made larger than before and sent to the variable speed control device (6) as a manipulated variable.

Therefore, if the variable speed control device (6) is composed of a variable voltage variable frequency inverter (hereinafter referred to as an inverter), it will output a frequency commensurate with the output signal of the pressure regulator (5). In this case, the frequency and voltage increase, and the electric motor (1) passes through the switch (7) and wiring (10).
). Since the electric motor (1) is an induction motor, its rotation is proportional to the frequency. Therefore, as the frequency increases, the rotational speed of the electric motor (1) increases, and its output is transmitted to the pump (2). 2) The rotational speed increases and the pressure increases.

Then, when the pressure rises, the pressure is transmitted as an electrical signal along the same path from piping (3) to pressure transmitter (4), and the manipulated variable is controlled by the pressure regulator (5), so that the pressure remains constant. .

In addition, when the flow rate decreases and the pressure increases, the same closed loop will be used: pressure transmitter (4) → pressure regulator (5) → variable speed controller (6) → switch (7) → electric motor (1) → In the path of pump (2) → pressure transmitter (4), the pressure regulator (5) becomes a deceleration signal, and the output frequency and voltage of the variable speed control device (6) decrease, so the rotation speed of the pump (2) is controlled so that the pressure decreases and the pressure remains constant.

Next, the flowchart shown in FIG. 4 for constant pressure control as described above, and the flow rate-total head curve shown in FIG.
Figure 5 shows the flow rate vs. total head curve for a centrifugal pump in which pump (2) uses centrifugal force.
is 100 [% 1 revolution, (17).

(18) is the flow rate-total head curve when the rotation speed of the pump is reduced, and (18) is the set pressure P in constant pressure control.
To explain this with reference to S), by performing such constant pressure control ((Sl, S2) in Fig. 4, in Fig. 5, when the flow rate used is Ql, Ql and the set pressure The pump (2) operates at a rotation speed that is a curve (17) passing through the intersection point A with Ps (19), and at this time, even if the flow rate increases to Q2, the rotation of the pump (2) may change due to some reason. If the speed had not increased, the process pressure P
p becomes less than the pressure drop alarm pressure pL (S3 in Figure 4)
, this pressure Pp<Pt is detected in the comparator (13) (S4 in FIG. 4), and after the detection time t1, the alarm circuit (14) issues a pressure drop alarm (85 in FIG. 4).

In addition, if the flow rate used abnormally increases to 03, the process pressure PP cannot be raised to the pressure drop alarm setting pressure pt (12) even if the pump (2) rotates once at 100r%, and the pressure drop is also prevented. The alarm circuit (14) is activated and a pressure drop alarm is issued.

[Problems to be solved by the invention] In the conventional pressure-feeding water supply system, there is no pressure drop alarm as described above, and there is no pressure drop discrimination device, so it takes time to investigate the cause of the pressure drop, and even a minor malfunction can be ignored. There was a problem in that the system would issue a pressure drop alarm and stop the pump, resulting in a water outage.

In this invention, the cause of pressure drop is determined from several items, and in the case of a minor failure such as a poor contact of an electric contact, the electromagnetic relay is turned on again to remove the cause of the poor contact and continue operation, thereby reducing the chance of water outage. The purpose is to reduce

[Means for Solving the Problems] In the pressurized water supply system according to the present invention, when a pressure drop occurs, the -bearing pump is driven by the commercial power supply, that is, operated at the maximum speed, and the pressure is increased depending on the state of pressure change at this time. This is to determine the cause of the decline.

[Function] The pressure drop determination means does not require new equipment and can be easily configured by adding a program to a conventional microcontroller. Investigation and recovery can be expedited.

[Example] An example of the present invention will be described below based on the figures.
In the figure, (1) to (13) show the same configuration as the conventional one, and (20) is a pressure drop discrimination circuit;
20) has the configuration shown in the flowchart of FIG.

In other words, (21) is a number counting circuit that detects the number of times the pressure has decreased, (22) is a switching means that switches to constant speed operation after the pressure has decreased, and (23) is the time t for constant speed operation.
2 usually takes about 1 to 10 minutes, and (24) returns the process pressure Pp and pressure drop alarm set pressure PL (12) after constant speed operation.
), (25) is a return means that returns to variable speed operation in case of a minor failure, and (26) is a first pressure drop alarm that outputs the first pressure drop alarm (A). (2?) is a second pressure drop alarm means for outputting a second pressure drop alarm (B), and (13) is the first comparison means shown in FIG.

In the above configuration, when a pressure drop occurs, the detection time t
1, the constant speed operation switching means (22) operates to open the variable speed operation switch (7) and close the constant speed operation switch (8) to switch off the motor (1). Powered by commercial power,
That is, the operation of the pump (2) is controlled at the maximum speed.

Here, the flow rate used by the pump when the pressure decreases is the fifth
If Q2 is shown in the figure and the flow rate vs. total head curve of the pump is (17), the pressure will rise from A2 to A3.

However, if the opening degree of the faucet is constant, the flow rate passing through the faucet will increase due to the increase in pressure, so the actual pressure will be A4.

After the constant speed operation time t2, the comparing means (24) again compares Pp and PL.
If PP>PL, the means for returning to variable speed operation (25
) to return to variable speed operation, normal operation will occur, and there will be no water outage. In this case, a pressure drop alarm will not be displayed. By performing constant speed operation, the pressure becomes the set pressure P.
The cause of L(12) or higher is the variable speed control device (
An example of this is when the rotational speeds of the electric motor a (1) and the pump (2) do not increase due to poor contact of the operation command contact point 6).

Next, even if you switch to constant speed operation, the second comparator stage (24
), if PP<PL, the first pressure drop alarm means (
28) will output a pressure drop alarm (A),
Stop pump (2).

The reason for this is as follows.

[11 Disconnection of the pressure transmitter (4) or its output signal (11) wiring.

[21 Use arrogance becomes Q3 or higher, pump (
2) Excessive flow rate using water exceeding the supply flow rate.

In addition, if the pressure decreases again within the set time of about 3 to 30 minutes after returning to variable speed operation by the return means (25), the pressure decrease count circuit (21) operates, and since this is the second time, the pressure decrease count circuit (21) operates. The pressure drop alarm means (27) of r
If E-force drop 2 alarm (B) is output, an alarm will be issued and the pump (2) will be stopped.

The reason for this is as follows.

[11 Pressure regulator (5) is malfunctioning.

[21 Variable speed control device (6) is out of order.

In the case of poor contact between the contacts, when the variable speed operation is performed again, the electromagnetic relay that has caused the poor contact also operates, causing the contacts to rub together and eliminate the poor contact.

In the above embodiment, the pressure control was explained using constant discharge pressure control, but multi-stage discharge pressure control,
Any control method for constant terminal pressure control may be used.

Furthermore, although the determination of pressure drop has been explained using a microcomputer program, a combination of a municipal relay and an analog circuit may also be used.

[Effects of the Invention] As described above, according to the present invention, [11] Only a microcomputer program is added to the conventional device, and there is no increase in hardware, so it is inexpensive.

[21 The cause of the pressure drop can be broadly classified, making investigation and restoration faster.

[3] Problems caused by poor contact can be self-repaired, reducing unnecessary pump stoppages and water outages, and improving continuity of water supply.

[Brief explanation of drawings]

Fig. 1 is a block diagram showing the overall structure of the present invention, Fig. 2 is a flowchart showing the partial detailed structure of Fig. 1, Fig. 3 is a block diagram showing the conventional overall structure, and Fig. 4 is similar to Fig. 2. The corresponding conventional flowchart, FIG. 5, is a curve diagram showing the pump characteristic curve and each pressure. In the figure, (2) is the pump, (3) is the piping, (7) is the speed change switch, (8) is the constant speed switch, (8) is the controller,
(13) is the first comparison means, (15] is the power supply,
(20) is a pressure drop discrimination circuit, (22) is a switching means,
(24) is a second comparison means, (25) is a return means, (26) is a first pressure drop alarm means, and (27) is a second pressure drop alarm means. Note that the same group numbers in each figure indicate the same or equivalent parts.

Claims (1)

[Claims] In a pressurized water supply system that controls the process pressure in piping by controlling the variable speed operation of a pump, a first comparison means detects a pressure drop in the piping based on comparison with a set pressure, and the number of times the pressure drop is the first. In the case of , a switching means for switching the operation control of the pump from the variable speed driving to the constant speed driving by commercial power supply driving, a second comparison means for comparing the process pressure after the constant speed driving and the set pressure, and the process pressure is A return means for returning to variable speed operation when the process pressure is higher than the set pressure, a first pressure drop alarm means for outputting a first alarm when the process pressure is lower than the set pressure, and when the number of pressure drops is the second or later. A pressurized water supply device comprising a second pressure drop alarm means for outputting a second alarm.