•
The pumps are included in the calculated volume. In this case,
the volume of the pumps must be deducted from the calculated
volume.
•
Any other physical factors in the pit affecting the calculated
volume.
The inlet flow is measured when the pumps are stopped and the pit
is being filled.
t
2
is the time it takes to fill the pit volume from height h
1
to height h
2
.
t
1
is the time it takes for one pump to drain the volume.
t2
t1
h2
h1
TM029106
The height in the pit in terms of time
The most accurate measurement is achieved if t
1
< t
2
.
The inlet flow is expected to be constant in the time period t
1
.
If the volume between h
1
and h
2
is called V, the pump flow Q
p
is
calculated by:
Q
p
=
V
t
1
+ t
2
t
1
x t
2
Related information
8.1.2 Pit configuration and flow calculation
8.1.3 Pump delays
Delays and switching times are set in this display.
Max. start-up delay
The start-up delay is the time that elapses from when the system is
switched on until the first pump is started.
The start-up delay time can vary between 0 second and the delay
time set by the user. This is done to ensure that the first pump and
the system do not start at the same time. If several Dedicated
Controls systems share the same power supply, it is best to stagger
pump start-ups to avoid overloading the power supply.
Min. switching time
•
Start → start delay: A start delay can be used to reduce the
starting current surge. In this way, an unintentional cutout of the
motor protection (excess-current circuit breaker, fuses, etc.) is
avoided. This function is only used when two pumps are
installed in the pit.
•
Stop ← stop delay: A stop delay can be used to reduce the
pressure surge generated when a pump is stopped. This
function reduces wear of the pump, pipes and valves.
•
Start ↔ stop delay: A start/stop delay can be used if the same
float switch is used to start and stop the pump. This function
creates a hysteresis so that the pumps do not start and stop
continuously, which would result in unnecessary wear. The start-
stop delay generates a ΔH in the pit which is higher than the
start level which depends on the inflow speed and the number of
seconds set in this display. The same applies to the stop level >
actual stop level. This function ensures longer cooling time for
the motor/pump and the electrical components.
After-run delay
The after-run delay is the time it takes for a pump to stop after it has
received a stop signal from a sensor.
After-run delay, high level
To prevent overflow if the level sensor is defective, a float switch
can be installed at the top of the pit. If this float switch is activated,
both pumps will start. This pumping period is called the "After-run
delay, high level". The actual time is best found by trial and error.
If a dry-running float switch is also installed, the pumps can drain
the pit down to the dry-running level.
This emergency situation is maintained until the defective
sensor is replaced and the alarm list is updated.
The time is set in seconds.
The "Conflicting levels" alarm must be activated to show
the fault in the alarm list.
Example
•
"Max. start-up delay" is set to 2 seconds to avoid overloading
the power supply.
•
"Start → start delay" is set to 2 seconds which reduces starting
current surges.
•
"Stop ← stop delay" is set to 2 seconds. This delay reduces the
pressure surge generated when a pump is stopped.
•
"Start ↔ stop delay" is set to 2 seconds. This delay creates a
hysteresis so that the pumps do not start and stop continuously.
•
"After-run delay" is set to 1 second. This delay is the time it
takes for a pump to stop after it has received a stop
signal from a sensor.
•
"After-run delay, high level" is set to 30 seconds. This delay is
used to prevent overflow if the level sensor is defective.
Path:
Settings > Basic functions > Pump delays
4-1-3_PUMP_DELA
YS_069
Pump delays
Related information
8.1.4.7 Analog sensor with safety float switches
25
English (GB)
