6-3
6.2
Check items related to automatic operation
Select “Automatic” with the
Operation
Selector
switch to perform automatic operation.
First, carefully read the following sections to understand how automatic operation works, and then confirm
that the unit runs properly in automatic modes using the test pipe. During the operation, also check each
pump for any abnormal pressure, noise, or vibration.
Note that you can change the Total Head setting and the Minimum Sustained Head setting from their factory
defaults, depending on the conditions on site. Follow the instructions in “7.5 Parameter setting” in such a
case.
Ჶ
Explanation about operation (2-pump Parallel, 3-pump Rotation type)
Ჸ
The “2-pump Parallel, 3-pump Rotation” operation uses 3 pumps. In this operation, the 3 pumps are
operated in rotation when the water consumption is below the max. water supply amount of one pump, and 2
pumps will be operated together in parallel when the water consumption exceeds the max. water supply
amount of one pump.
(1) When the hydrant is opened and the water
is consumed, the pressure inside the
discharge pipe will decrease. When the
pressure inside the discharge pipe
decreases to near the preset min. pump
head (P
L
), it is detected by the pressure
transmitter, which makes the pump to start.
(2) While the water consumption is below the
max. water supply amount (Q
3
), the
discharge pressure is changed from P
L
to
P
H
by controlling the rotating speed with the
inverter according to the
increase/decreased in water consumption,
which makes the estimated terminal
pressure constant-controlled.
(3) When the water consumption increases to
near the water supply amount of the 2nd
parallel pump (Q
2
), the 2nd pump starts operating.
(4) If the water supply amount changes even while 2 pumps are operated in parallel, the operation
continues at pressure corresponding to the unit discharge curve.
(5) When the water consumption decreases and the pressure decreases to below the water supply amount
of the 2nd unit in parallel operation (Q
2
), the 2nd pump stops and the 1st pump only continues the
operation.
(6) When the water consumption decreased to below the stop flow rate (Q
1
), it is detected by the flow
switch, which makes the pump to stop. While the pump is stopped, the operation indicator lamp will
blink. (See 7.5.3.)
(7) When the hydrant is opened and the water is used again, the pump which has been stopped starts
operating as above.
Fig.6-2 2-pumps parallel 3-pumps rotation
Operations based on the above operation should be performed
for other operation method.
Note
P
H
: Total head
P
L
:
Minimum sustained head
Q
1
: Stopping flow rate approx. 10L/min
or less
Q
2
:
Parallel water flow
Q
3
: Maximum water supply (with two pumps)
Discharge pressure
Discharge
curve of
the unit
Specified
point
Performance curve at
maximum frequency
(with one pump)
Water supply
Q
3
Q
2
P
L
P
H
Performance curve at
maximum frequency
(with two pumps)
