Start and stop levels
The difference in level between start and stop can be
adjusted by changing the free cable length.
Long free cable = large difference in level.
Short free cable = small difference in level.
Both the two following points must be
Note
observed.
•
To prevent air intake and vibrations, install the
stop level switch in such a way that the pump is
stopped before the liquid level is lowered below
the upper edge of the clamp on the pump.
•
Install the start level switch in such a way that the
pump is started at the required level; however,
the pump must always be started before the
liquid level reaches the bottom inlet pipe to the
pit.
Warning
The CU 100 control box must not be used
FM
for explosion proof applications.
See section
8.3 Pump
Warning
The pump must not run dry.
An additional level switch must be installed
to ensure that the pump is stopped in case
the stop level switch is not operating. See
fig. 7.
The pump must be stopped when the
liquid level reaches the upper edge of the
FM
clamp on the pump.
Float switches used in potentially
explosive environments must be approved
for this application.
They must be connected to the Grundfos
DC, DCD and LC, LCD 108 pump
controller via an intrinsically safe barrier to
ensure a safe circuit.
Fig. 7
Start and stop levels
14
controllers.
Alarm
Start
Stop
8.3 Pump controllers
The following LC and LCD pump controllers are
available:
LC controllers are for one-pump-installations and
LCD controllers are for two-pump-installations.
•
LC 107 and LCD 107 with air bells.
•
LC 108 and LCD 108 with float switches.
•
LC 110 and LCD 110 with electrodes.
In the following description, "level switches" can be
air bells, float switches or electrodes, depending on
the pump controller selected.
Controllers for single-phase pumps incorporate
capacitors.
LC: The controller is fitted with two or three level
switches: One for start and the other for stop of
pump. The third level switch, which is optional, is for
high-level alarm.
LCD: The controller is fitted with three or four level
switches: One for common stop and two for start of
the pumps. The fourth level switch, which is optional,
is for high-level alarm.
When installing the level switches, the following
points should be observed:
•
To prevent air intake and vibrations, install the
stop level switch in such a way that the pump is
stopped before the liquid level is lowered below
the middle of the motor housing.
•
The start level switch should be installed in such
a way that the pump is started at the required
level; however, the pump must always be started
before the liquid level reaches the bottom inlet
pipe to the pit.
•
The high-level alarm switch, if installed, should
always be installed about 10 cm above the start
level switch; however, the alarm must always be
given before the liquid level reaches the inlet pipe
to the pit.
For further settings, see the installation and
operating instructions for the pump controller
selected.
Warning
The pump must not run dry.
An additional level switch must be installed
to ensure that the pump is stopped in case
the stop level switch is not operating.
Stop the pump when the liquid level
reaches the upper edge of the clamp on
FM
the pump.
Float switches used in explosive
environments must be approved for this
application. They must be connected to
the Grundfos LC, LCD 108 pump controller
via the intrinsically safe LC-Ex4 barrier to
ensure a safe circuit.