Systems With 3 Float Switches; Electrical Connection; Setting - Grundfos LC 108 Montage- Und Betriebsanleitung

5. Systems with 3 float switches

Description (see also page 189 or 190):
The pump is controlled by the liquid level in the pit.
• The float switch, pos. 2, starts the pump.
• The float switch, pos. 1, stops the pump. It is possible to set a
"stop delay" which delays the stop of the pump.
• The top float switch, pos. 3, activates the high-level alarm.
Warning
Before starting any work on pumps used to pump
liquids which could be constituted as being
hazardous to health, thorough cleaning/venting
of pumps, pits, etc. must be carried out
according to local regulations.
Before making any connections in the LC 108 or
work on pumps, pits, etc., it must be ensured that
the electricity supply has been switched off and
that it cannot be accidentally switched on.

5.1 Electrical connection

3 float switches, pages 189 and 190.
Warning
Before starting work on the system, switch off
the supply voltage and lock the mains switch in
position 0.
Any external voltage connected to the system
must be switched off before work is started.
Fig. B1 on page 189.
The figures show all electrical connections required to connect
the LC 108 for direct-on-line starting, 3 float switches.
Fig. B2 on page 190.
The figure shows all electrical connections required to connect
the LC 108 for start-delta starting, 3 float switches.
Warning
The LC 108 must be connected in accordance
with the rules and standards in force for the
application in question.
The operating voltage and frequency are marked on the controller
nameplate. Make sure that the controller is suitable for the
electricity supply on which it will be used.
All cables/wires must be fitted through the Pg cable entries and
gaskets (IP65).
Maximum back-up fuse is stated on the controller nameplate.
If required according to local regulations, an external mains
switch must be installed.
If the PTC resistance/thermal switch of the motor
Caution
is connected, the factory-fitted short-circuit
jumper must be removed (terminals T11-T21).
Single-phase motors must be connected to an external operating
capacitor and in certain cases also to a starting capacitor.
Further details can be found in the installation and operating
instructions for the pump in question.
Warning
Float switches or electrodes placed in an
explosion hazard area must be connected via an
EEx barrier, e.g. Grundfos number 96440300.
The EEx barrier must not be installed in the
explosion hazard area.
Equipment used in explosion hazard areas must
in each individual case have been approved for
this particular application. Furthermore, the
cables into the explosion hazard area must be
laid in accordance with local regulations.
Float switches of the same type as Grundfos
product number 96003332 or 96003695, i.e. float
switches with gold-plated contacts suitable for
Note
low voltages and currents (40 V/100 mA), must be
used. All EEx-approved float switches are also
suitable.
The float switches must be connected as NO contacts, i.e. brown
and black leads, when float switches, Grundfos product number
96003332 or 96003695, are used.
Key to the symbols in fig. B1 on page 189 and fig. B2 on
page 190:
Pos. Description
1 Float switch for stop of pump.
2 Float switch for start of pump.
3 Float switch for high-level alarm.

5.2 Setting

3 float switches, pages 189 and 190.
The CU 211 module has a 10-pole DIP switch in the bottom right
corner, see fig. 8.
The controller must be off circuit to ensure the
Caution
correct configuration during start-up after
change of the DIP switch setting.
The DIP switch setting offers the following possibilities:
• selection of starting delay and automatic test run (switch 4),
• setting of stop delay (switches 5, 6 and 7),
• selection of automatic alarm resetting (switch 9),
• selection of automatic restarting (switch 10).
Fig. 8
Set the DIP switch as shown in fig. 8.
Each individual switch (1 to 10) of the DIP switch can be set to
position OFF or ON.
The DIP switch must not be set to other switch
Note combinations than those described in this
section.
Terminal number
11-12
21-22
31-32
13