Pump Controllers; Thermal Switches - Grundfos DP 10.50 Original Installation And Operating Instructions

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.
The LC 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.
The LCD 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, observe the
following points:
• 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.
• 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 tank.
• If installed, always install the high-level alarm
switch 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 tank.
For further information, 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.
The pump must be stopped when the
liquid level reaches the upper edge of
the 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 or LC, LCD 108
pump controller via an intrinsically safe
barrier to ensure a safe circuit.

8.4 Thermal switches

All pumps have two sets of thermal switches
incorporated in the stator windings.
Thermal switch, circuit 1 (T1-T3), breaks the circuit
at a winding temperature of approx. 150 °C.
This thermal switch must be connected
Note
for all pumps.
Thermal switch, circuit 2 (T1-T2), breaks the circuit
at a winding temperature of approx. 170 °C
(three-phase pumps) or 160 °C (single-phase
pumps).
Warning
After thermal cutout, explosion-proof
pumps must be restarted manually.
The thermal switch (circuit 2) must be
connected for manual restarting of
these pumps.
Maximum operating current of the thermal switches
is 0.5 A at 500 VAC and cos ϕ 0.6. The switches
must be able to break a coil in the supply circuit.
In the case of standard pumps, both thermal
switches can (when closing the circuit after cooling)
generate automatic restarting of the pump via the
controller.
Warning
The separate motor-protective circuit
breaker/control box must not be
installed in potentially explosive
environments.
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