JP3053346B2 - Water supply device - Google Patents

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, and more particularly, to a water supply device.
The present invention relates to a water supply apparatus suitable for continuing automatic operation when water supply is resumed after water supply is temporarily stopped due to water supply reduction due to water supply restriction or power failure due to an accident or the like.

[0002]

2. Description of the Related Art There are two types of water supply systems: a water tank system in which a water tank is provided between a water main and a water system, and a direct connection system in which a water system is directly connected to a water distribution pipe. These methods will be described with reference to FIGS.

FIG. 6 is a system diagram of a water supply system of a water receiving tank type, wherein 1 is a water main pipe, 2 is a water main branch pipe, and 3 is a pipe for supplying clean water to the water receiving tank 5 from the water main branch pipe. , A constant water level valve (ball tap), 4 a water level detecting means for detecting a water level in the receiving tank, 6 a suction valve provided with a gate valve 7 on the way to connect the water supply pump 8 to the water receiving tank 5, 9 a non-return valve, 10 is a gate valve, 11 is a pressure tank having an air reservoir inside, 13
Are the discharge side of the water supply pump 8 and the demand side water supply devices 14a to 14a.
4d.

[0004] PS2 is a pressure detecting means which is closed below the lower limit pressure P1 and opened above the upper limit pressure P2 as shown in the pump operation characteristics of FIG. Similarly, PS1 is a pressure detecting means for detecting a discharge pressure drop state and detecting a water pumping impossible state due to an air pool on the suction side of the water supply pump 8, and is provided upstream of the check valve 9. . This PS1 is shown in FIG.
Is set to close at a pressure PL or less and return at PL '.

FIG. 8 shows a control device of the water supply system shown in FIG.
a (the contact of the pressure switch PS2 described above), 52 (the operation switch of the pump), 49 (the contact of the overload protection relay of the pump), and the output contact 63X1 of the discharge pressure drop detection circuit X
b, composed of a series circuit of output contacts 33WXb of the water level detection circuit Y.

A circuit X is a discharge pressure detecting circuit, which comprises a switch SS1, a contact PS1a of a pressure switch PS1, a timer T1, a relay 63X1, and a display lamp O1. That is, the switch SS1 is closed, and the discharge pressure is reduced to P shown in FIG.
When it falls below L, the contact point PS1a of the pressure switch PS1
Is closed, Ru timer T1 is energized. After the energization, when the timer T1 finishes counting, its contact T1a closes,
Relay 63X1 is energized, the lamp O1 to mean a self-holding Rutotomoni, the discharge pressure drop at its contacts 63X1a
Lights up.

A receiving tank water level detecting circuit Y comprises a liquid level relay 33W, a relay 33WX, and a water reduction indicator lamp O2. When the water level detection means 4 shown in FIG. 7 drops below the stop water level, the liquid level relay 33W closes the contact 33WC on the a side, and when the water level detection means 4 reaches the return water level or higher, switches from the a side to the b side. When closed to a side, relay 33W
X is excited and its contact 33WXa is closed.
Then, the water reducing lamp O2 is turned on.

A pump (not shown) is usually a pressure switch.
Driving when PS2 is closedIs, OpenShut down
However, as a protection function of the pump,
The contact 63X1b of the relay 63X1 described above is opened, or
The reduced water level of the receiving tank 5 works, and the contact 33W of the relay 33WX
When Xb opens, the operation circuit A opens, and the pump stops.
I do.

With such a protection function, the pump stops when the water level in the water receiving tank falls below the water reduction level due to a power outage (including a work outage) or water shortage. However, as long as there is water in the pressure tank 11 and the water pipe 13, the water is consumed by the consumer, and eventually the water is consumed until the water is not discharged even if the terminal faucet is opened. In such a state, even if the power is restored or the water shortage is resolved, the discharge pressure drop detection circuit X operates and the water is cut off.

That is, when the water level in the receiving tank reaches or exceeds the return water level, the pump operates, but the pressure tank 11 and the water pipe 1
3 is empty, these are filled with water within the time measured by the timer T1 (FIG. 8), and the feed water pressure cannot be increased to the return pressure PL 'shown in FIG. relay 63X1 been energized, is because thereby the pump is stopped. As a countermeasure at the time of power recovery, it is conceivable to lengthen the time measured by the timer T1, but if this time is lengthened, it will no longer serve the role of protection during normal use.

FIG. 9 is a block diagram showing an example of a water supply system directly connected to a water supply, wherein 1 is a water main pipe, 2 is a water distribution pipe, 6 and 10 are gate valves, and 8 is a pump which is driven by an inverter in this example. . 9 is a check valve, 11 is a pressure tank, 13 is a water pipe,
PS3 is a pressure sensor provided on the pump suction side water pipe, is set as shown in FIG. 10. That is, the pump is stopped when the water distribution pipe pressure becomes equal to or less than L3, and a stop signal for restarting the operation after a certain time (for example, 5 to 10 seconds) has elapsed after the water level has risen and the water level has risen. PS2 is the same as the pressure switch described with reference to FIG.

FIG. 11 shows a control device for operating the water supply system of FIG. ELB is an earth leakage breaker, INV is an inverter for controlling the rotation speed of the pump according to the load fluctuation, and supplying water while keeping the pressure on the discharge side at a constant pressure. The operation speed command N is given. X is the same as the discharge pressure detection circuit X shown in FIG. Z is a suction-side pressure detection circuit including a switch SS2, a contact PS3a of a pressure switch PS3 for detecting suction-side pressure, a timer T2, a relay 63X2, and a lamp O3 for indicating a decrease in suction-side pressure. PS3 falls below L3 shown in FIG.
When the time measurement is completed, the contact T2a is closed and the relay 6
3X2 is Ru is biased.

Reference numeral B denotes an alarm circuit for issuing an alarm by a buzzer BZ when the discharge pressure or the suction side pressure decreases. A is an operation circuit similar to that of FIG.
Instead of Xb, output contact 63X of suction side pressure detection circuit Z
2b, these protection circuits are activated when the discharge pressure drops or the suction side pressure (which occurs when the water supply company lowers the mains water pressure due to construction outage or water shortage). Pump stops. In this case as well, the water supply company restricts the water supply as in the previous example, or the circuit A is opened due to construction outage or power outage and the pump stops. However, even if these conditions are canceled, the tank 11
And water is consumed while there is water in the water pipe 13,
Again, as in the previous example, the discharge pressure drops and water supply becomes impossible.

[0014]

The above-mentioned prior art has the following problems. In other words , in the event of a shortage of water, especially in the summer, the water supply company restricts the water supply, or the water supply from the water supply source is cut off at the time of construction outage or power outage, so that the customer can remove the water stored in the pressure tank or water supply pipe. When the water has been consumed, even if these conditions are canceled and the water can be used as the water supply source, the discharge pressure is reduced and the water cannot be supplied.

Further, once the <br/> the discharge pressure drop is detected, as described above, since the effect is self-holding (storage), maintenance (maintenance) artisan to go to the scene , Reset (turn off the power and turn on again) to release the operation of the discharge pressure drop detection circuit X, and open the switch SS1 until the discharge side water pressure recovers to PL or more shown in FIG. .

It is a main object of the present invention to automatically reset the apparatus to enable water supply without going to the site if the water supply of the water supply source becomes possible, even if the discharge pressure is reduced, thereby making it impossible to pump water. It is to provide a water supply device that can be eliminated.

[0017]

The object of the present invention is to provide a pressure detecting means for detecting the pressure on the discharge side of a pump which draws in water and discharges it to a demand side.
And a discharge detected by the pressure detecting means.
Since the outlet side pressure becomes below the specified value, test after a predetermined time
In a water supply device having a protection function of stopping the operation of the pump when the output pressure on the discharge side is also equal to or lower than a specified value, after the power supply of the pump is turned on or after the power failure is restored ,
For starting the pump when the protection function is not working yet
In this case, after the pump is started, the discharge pressure becomes the return pressure.
Until sufficient time has elapsed to raise at least force Nima,
This is achieved by providing means for keeping the pump in operation .

Another object of the present invention is to detect the discharge side pressure of a pump that sucks in water and discharges it to a demand side by pressure detecting means.
In addition, in a water supply device having a protection function of stopping the operation of the pump when the state in which the discharge-side pressure detected by the pressure detecting means is equal to or less than a specified value continues for a timer time, when the power to the pump is turned on. , Or the pump when the protection function has not been activated yet when the power failure is recovered
When starting the pump, after starting the pump, the discharge side pressure
Sufficient time elapses before the pressure rises above the return pressure
Until the pump is in operation .

Another object of the present invention is to detect a discharge side pressure of a pump which draws in water and discharges it to a demand side by pressure detecting means.
In addition, the discharge side pressure detected by the pressure detecting means becomes equal to or less than a specified value, and is detected after the timer count time.
In a water supply device having a protection function of stopping the operation of the pump when the discharge-side pressure is also equal to or lower than a specified value , the pressure detection means is provided when the power of the pump is turned on or when the power is restored.
Until the discharge side pressure force detected by stage reaches a specified pressure is achieved by providing a means for driving the pump.

The object of the present invention is also to detect a discharge side pressure of a pump which sucks in water and discharges it to a demand side by pressure detecting means.
In addition, the operation of the pump is stopped when the discharge side pressure detected by the pressure detecting means becomes equal to or less than a specified value .
1 protection function and the water level in the receiving tank
The water level detected by the water level detection means
When the water level is detected to be below the fixed water level, the operation of the pump is stopped.
A water supply device having a second protection function for stopping the water supply;
After the operation of the pump working the first protection function has stopped, before the water level in the water tank is above a predetermined level
When serial level detecting means has detected, it is achieved by providing a means for the operating state of the pump is stopped by the first protection.

[0021] The above object is also achieved by a first pressure detecting means for detecting a discharge side pressure of a pump which draws in water and discharges it to a demand side.
After the detection, the discharge detected by the first pressure detecting means is detected.
A first protection function for stopping the operation of the pump when the outlet pressure falls below a specified value, and a suction pressure of the pump.
Is detected by the second pressure detecting means, and the second pressure
If the suction side pressure detected by the detection means is equal to or less than the predetermined pressure
To stop the operation of the pump when detected.
In the water supply device having a protection function, after the operation of the pump working the first coercive <br/> protection function has stopped, the that the suction-side pressure of the pump is above a predetermined pressure the second
When the pressure detecting means detects the are achieved by providing a means for the operating state of the pump is stopped by the first protection.

The above object is to suck water and discharge it to the demand side.
The pressure on the discharge side of the pump was detected by the pressure detection means.
Above, the discharge side pressure detected by the pressure detecting means is specified.
The discharge detected after a predetermined time from when the
When the outlet pressure is below the specified value, the operation of the pump is stopped.
Having a first protection function for turning on the pump,
Or after the power failure recovery, the first protection function still works
When starting the pump with no pump, start the pump.
After the operation, the discharge side pressure rises to the return pressure or more.
The pump is running until sufficient time has passed.
A water supply system comprising
The pump is stopped by the second protection function based on the detection of the decrease in the side pressure by the suction side pressure detection means , and the discharge is stopped.
The first protection function was activated by detecting a drop in the outlet pressure.
Later, when the suction side pressure becomes equal to or higher than a predetermined pressure, the
This is achieved by providing a means for automatically starting the pump after resetting one of the protection functions .

[0023] The above object is also achieved by that the pressure on the discharge side of the pump which sucks in water and discharges it to the demand side is set to a specified value by pressure detecting means.
In the water supply device having a first protection function of stopping the operation of the pump when detected as follows, when the operation of the pump is stopped due to a power failure and the power is thereafter restored,
Detect a drawdown by receiving tank in the water level the water level detecting means
A second protection device for stopping the operation of the pump when the
Function to stop the pump and detect a drop in the discharge side pressure
After the first protection function, the water level in the receiving tank
When the water level exceeds a certain level, reset the first protection function
And means for automatically starting the pump.

It is another object of the present invention to provide a water supply device having a protection function for stopping the operation of a pump when a detected pressure on a discharge side of the pump that sucks in water and discharges the water to a demand side becomes a specified value or less. Is stopped, and when the power is restored after that, when it is detected that the pressure on the suction side of the pump has become equal to or higher than a predetermined pressure, it is also possible to provide a means for automatically starting the pump regardless of the protection function. Is done. The above object also has a protection function of stopping the operation of the pump when the discharge side detection pressure of the pump that sucks in water and discharges it to the demand side becomes equal to or less than a specified value,
A function of stopping the operation of the pump when it is detected that the detected pressure on the suction side of the pump has dropped to a predetermined pressure or less, wherein when the operation of the pump is stopped, the suction of the pump is stopped. This is also achieved by providing a means for automatically starting the pump regardless of the protection function when it is detected that the side pressure has become equal to or higher than a predetermined pressure.

[0025]

[Function] In the case such as after recovery from a power failure, after starting the pump,
When the discharge side pressure is sufficient to increase to the return pressure or more
Until the time has elapsed and the pump
Then , the automatic operation can be continued without going to the site and resetting the device.

[0026]

An embodiment of the present invention will be described below with reference to the drawings. FIG. 1 is a configuration diagram of a water supply device according to a first embodiment of the present invention. The embodiment of FIG. 1 is obtained by adding a power supply confirmation circuit unit I to the configuration of FIG. 8 described in the related art.
Therefore, description of the same components as those in FIG. 8 will be omitted. In FIG. 1, T3 is a timer for checking the power supply, which is set to about 10 minutes. T3a is a time-limit contact of the timer, contact to close in about 10 minutes after urging, 27X is a relay, the biasing of when the time-limit contact T3a of the timer T3 is closed
It is, is self-holding in its own contact 27Xa, contact 27Xb
Resets the timer T3. Further, the contact 27Xa
Is connected as an input condition of the timer T1 of the discharge pressure detection circuit X.

[0027] There is enough water in the receiving water tank For example, water-reducing position is not in operation (33WXb is closed), a power failure is released (including a power failure during construction), urging timer T3 is Is
However, since the set time is about 10 minutes, its own contact T3a is not yet closed. Therefore, the output contact 63X1b of the discharge pressure detection circuit X is not closed. When the customer uses water in this state, the pressure detecting means PS2 is closed, the pump is operated, and water is supplied to the pressure tank and the water supply pipe 13. Since the timer T3 is sufficiently long, that is, about 10 minutes, the pressure of the pressure tank and the water supply pipe is sufficiently increased before the timing of the timer T3 is completed, and the pump discharge pressure is reduced by the discharge pressure detecting means P.
It rises above the return pressure PL 'of S1 (FIG. 7). Therefore, after the expiration of T3, when the own contact T3a is closed, the contact of the discharge pressure detecting means PS1 is open, and the discharge pressure detecting circuit X does not operate.

Although the present embodiment has been described with reference to the example of FIG. 8 of the water receiving tank type, the same applies to FIGS . 9 and 11 relating to the direct connection type.

FIG. 2 is a block diagram of engagement Ru water supply device in the second embodiment (receiving tank method) of the present invention. The embodiment of FIG.
In addition to the configuration of FIG. 8, a reset circuit of section C is provided, and a timer T4 is connected to the contact b side (return side) of the liquid level relay 33W, water shortage is eliminated, and the water level of the water receiving tank becomes equal to or higher than the E1 water level. Then (for example, detection with an electrode bar or the like), the own contact 33WC closes from the a side to the b side, and the timer T4 is energized. Then, the contact T4a closes, for example, after 30 seconds (returns after a certain time), and the reset relay RSX
To excite. That is, the contact R of the reset relay RSX
SXb releases the self-holding of the relay 63X1 of the discharge pressure detection circuit X, so that the pump can be operated.

FIG. 3 shows a third embodiment of the present invention (direct connection type).
A is a configuration diagram of engagement Ru water supply device. The embodiment of FIG.
In addition to the configuration of the first embodiment, a reset circuit of the D section is provided similarly to the second embodiment, and the pressure detection means PS3 provided on the suction side is provided.
As a result, the suction side pressure becomes, for example, the pressure level L shown in FIG.
After detecting 3, the self-holding (including storage) of the discharge pressure detecting circuit X is released based on this signal after a certain time (for example, 30 seconds). That, in FIG. 3, when the suction side pressure detection means PS3 detects the suction side pressure L 3 than above, its contacts PS3C closes the b side from a side. At this time, the timer T5 is activated , and when a set time, for example, 30 seconds, elapses (D part), the contact T5b is opened, the self-holding circuit of the relay 63X1 is released, and the pump is returned to the operable state (X Department).

FIG. 4 is a block diagram of a water supply apparatus according to a fourth embodiment of the present invention. This embodiment of the water receiving tank type can cope with a power outage and water shortage. In the present embodiment, the I section described in the first embodiment and the circuit C section described in the second embodiment are provided. That is, as described above , after recovery from the power failure, the discharge pressure is not detected by the circuit I for about 10 minutes, and the discharge pressure is restored to a specified value or more by operating the pump. Further, after the water shortage is resolved, the operated discharge pressure drop state is reset by the circuit C section.

[0032] FIG. 5 is a block diagram of the engagement Ru water supply device to a fifth embodiment of the present invention, in this embodiment of the direct coupling system, it can cope with a power failure and water shortage. This embodiment is provided with the D section described in the third embodiment and the I section described in the fourth embodiment. The operation after the recovery from the power failure is the same as that described above, and a description thereof will be omitted. However, after the water shortage is resolved, the activated discharge pressure drop state is reset based on the circuit section D, that is, the suction side pressure recovery signal. .

According to the above embodiment, after the power recovery, since discharge pressure detection sensor is provided with a timer for measuring a time sufficient exceeds the detection level PL ', the discharge pressure
In the meantime, the protection function that works when the
No. Furthermore, after the discharge pressure drop is detected, the recovery of pressure of the pump suction side, or water tank based on the recovery of the water level, the discharge
Runode self-holding of the effect that the pressure drop is reset, there is an effect that can also avoid the suspension of water supply by the discharge pressure drop.

Although the above embodiment uses a relay circuit, the pressure detecting means and the water level detecting means may be of an electronic type, and an electronic circuit or a microcomputer is used for the control circuit, and these functions are implemented by software. Obviously, it may be realized by hardware.

[0035]

According to the present invention, in the case such as after a power failure recovery
After the pump starts, the discharge side pressure should be higher than the return pressure.
Run the pump until enough time to
As a result of being in the rolling state, the discharge pressure does not decrease and the operation becomes impossible.

[Brief description of the drawings]

FIG. 1 is a control circuit diagram of a water supply device according to a first embodiment of the present invention.

FIG. 2 is a control circuit diagram of a water supply device according to a second embodiment of the present invention.

FIG. 3 is a control circuit diagram of a water supply device according to a third embodiment of the present invention.

FIG. 4 is a control circuit diagram of a water supply device according to a fourth embodiment of the present invention.

FIG. 5 is a control circuit diagram of a water supply device according to a fifth embodiment of the present invention.

FIG. 6 is a system diagram of a water supply system of a water receiving tank type.

FIG. 7 is a pump operation characteristic diagram.

FIG. 8 is a control circuit diagram of the water supply system system diagram shown in FIG. 6;

FIG. 9 is a configuration diagram illustrating a water supply system directly connected to a water supply.

FIG. 10 is an explanatory diagram showing a state of setting a pressure sensor.

FIG. 11 is a control circuit diagram for operating the water supply system of FIG. 9;

[Explanation of symbols]

4 ... water level detecting means, 5 ... water receiving tank, 8 ... pump, PS1,
PS2, PS3: Pressure detection means, A: Pump operation circuit section, I: Power supply confirmation timer circuit, BZ: Buzzer, X:
Discharge pressure drop detection circuit, Z: water receiving tank water level detection circuit.

──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Shinobu Ishida 7-1-1 Higashi Narashino, Narashino City, Chiba Pref. Hitachi, Ltd. Industrial Equipment Division (56) 58) Field surveyed (Int. Cl. ⁷ , DB name) F04D 15/00

Claims (9)

(57) [Claims] 1. A pressure detecting means for detecting a pressure on a discharge side of a pump for sucking water and discharging the water to a demand side.
In the water supply device having a protection function of stopping the operation of the pump when the discharge-side pressure detected by the outlet means is equal to or less than a specified value and the discharge-side pressure detected after a predetermined time is also equal to or less than a specified value. After turning on the pump ,
Or after power failure recovery , the protection function is not working yet
When starting the pump in the state, after starting the pump,
Enough for the discharge side pressure to rise above the return pressure
Means for keeping the pump in an operating state until a predetermined time elapses . 2. A pressure detecting means for detecting a pressure on a discharge side of a pump for sucking water and discharging the water to a demand side.
In a water supply device having a protection function of stopping the operation of the pump when the state in which the discharge side pressure detected by the outlet means becomes equal to or less than the specified value continues for the timer time, when the power to the pump is turned on or when the power failure is restored Said protection
When starting the pump when the function is not working yet
After starting the pump, the discharge side pressure is equal to or lower than the return pressure.
Until enough time has passed to ascend to the top
A water supply device comprising means for keeping a pump in an operating state . 3. A pressure detection means detects a discharge side pressure of a pump which sucks in water and discharges the water to a demand side, and detects the pressure.
The discharge-side pressure detected by the discharge means is equal to or less than a specified value, and the discharge-side pressure detected after the timer time has elapsed.
In a water supply device having a protection function for stopping the operation of the pump when the power is also equal to or less than a specified value , the pressure detection means detects when the power of the pump is turned on or when the power is restored.
Until the discharge side pressure force issued reaches a specified pressure, the water supply device, characterized in that it comprises means for driving said pump. 4. A discharge side pressure of a pump which draws in water and discharges it to a demand side is detected by pressure detection means.
A first protection function for stopping the operation of the pump when the discharge-side pressure detected by the outlet means falls below a specified value.
And, after detecting the water level in the receiving tank by the water level detecting means,
The water level detected by the water level detection means is equal to or lower than a predetermined water level.
To stop the operation of the pump when detected.
In the water supply device having a protection function, after the operation of the pump working said first holding <br/> protection function has stopped, the water level detecting hand that the water level in the water tank is above a predetermined level
A water supply device comprising: means for setting the pump stopped by the first protection function to an operable state when a stage is detected. 5. A discharge pressure of a pump which draws in water and discharges it to a demand side is detected by a first pressure detecting means.
The stopping operation of the pump when the discharge pressure detected by the first pressure detecting means becomes equal to or less than the specified value 1
And protection, the suction side pressure second pressure detection of said pump
After detecting by the output means, the second pressure detecting means
Detected suction side pressure is detected as lower than the specified pressure
In the water supply device and a second protection function to stop the operation of the pump when, after the operation of the pump working the first protection function has stopped, the suction side pressure of the pump
The second pressure detecting means determines that the force is equal to or higher than a predetermined pressure.
When There detected, the water supply device, characterized in that it comprises means for ready to operate the pump stopped at the first protection. 6. A pump for sucking water and discharging it to a demand side.
The discharge side pressure is detected by pressure detection means, and the pressure
The discharge side pressure detected by the discharge means is below the specified value.
The discharge-side pressure detected after a predetermined time from when
The first maintenance that stops the operation of the pump when the
Protection function, after the pump is turned on or after a power failure.
On return, with the first protection function not yet working
When starting the pump, after starting the pump, the discharge
Sufficient time for the outlet pressure to rise above the return pressure
Means for keeping said pump in an operating state until
The water pressure on the suction side of the pump
Second by that but detected by the suction-side pressure detecting means
Stop the pump with the protection function of
After the first protection function by the lower detection is activated, the suction
When the side pressure exceeds a predetermined pressure, the first protection function
And a means for automatically starting the pump after resetting . 7. A discharge side pressure of a pump which draws in water and discharges it to a demand side is detected as being equal to or less than a specified value by a pressure detecting means.
In the water supply device having the first protection function of stopping the operation of the pump when the operation is performed, when the operation of the pump is stopped due to the power failure and the power is restored after that, the water level in the water receiving tank is reduced.
When the water level is detected by the water level detection means as a decrease in the water level,
The second protection function for stopping the operation of the pump
The first protection by stopping the discharge and detecting the drop of the discharge side pressure
After the function is activated, the water level in the receiving tank becomes higher than the predetermined water level.
The water supply device further comprises means for automatically starting the pump after resetting the first protection function . 8. A water supply device having a protection function for stopping the operation of a pump when a discharge side detection pressure of a pump that sucks in water and discharges it to a demand side becomes equal to or lower than a specified value.
Means for automatically starting the pump irrespective of the protection function when it is detected that the pressure on the suction side of the pump has become equal to or higher than a predetermined pressure when the operation of the pump is stopped due to a power failure and thereafter the power is restored. A water supply device comprising: 9. A protection function for stopping the operation of the pump when the detected pressure on the discharge side of the pump that sucks in water and discharges it to the demand side becomes lower than a specified value, and the detected pressure on the suction side of the pump becomes lower than a predetermined pressure. In a water supply device having a function of stopping the operation of the pump when detecting that the pressure has decreased, when the operation of the pump is stopped, it is detected that the suction side pressure of the pump has become equal to or higher than a predetermined pressure. A water supply device for automatically starting the pump regardless of the protection function.