Other Connections - Three-Phase Pumps; Signal Cables - Grundfos LME Series Installation And Operating Instructions Manual

2.5 Other connections – three-phase pumps
The connection terminals of external potential-free contacts for
start/stop and digital function, external setpoint signal, sensor sig-
nal, GENIbus and relay signal are shown in figs. 10 and 11.
Note: If no external on/off switch is connected, short-circuit termi-
nals 2 and 3 using a short wire.
Note: As a precaution, the wires to be connected to the following
connection groups must be separated from each other by rein-
forced insulation in their entire lengths:
1. Inputs (external start/stop, digital function, setpoint and sen-
sor signals, terminals 1-8, and bus connection, A, Y, B).
All inputs (group 1) are internally separated from the mains-
conducting parts by reinforced insulation and galvanically
separated from other circuits.
All control terminals are supplied by protective extra-low volt-
age (PELV), thus ensuring protection against electric shock.
2. Output (relay signal, terminals NC, NO, C).
The output (group 2) is galvanically separated from other cir-
cuits. Therefore, the supply voltage or protective extra-low
voltage can be connected to the output as desired.
3. Supply voltage (terminals L1, L2, L3).
A galvanically safe separation must fulfil the requirements for re-
inforced insulation including creepage distances and clearances
specified in EN 50 178.
Fig. 10
MGE 90 and MGE 100
0/4-20 mA
0-5/10 V 4-20 mA
10 k
0-5/10 V
0/4-20 mA
C NO NC
Signal relay
L1
L2
L3
8
8: +24 V
7: Sensor input
6: GND (frame)
5: +5 V
4: Setpoint input
3: GND (frame)
2: Start/stop
1: Digital input
A: RS-485A
Y: Screen
B: RS-485B
Mains
connection
Fig. 11
MGE 112 and MGE 132
0/4-20 mA
0-5/10 V 4-20 mA
10 k
0/4-20 mA 0-5/10 V

2.6 Signal cables

• Use screened cables having a cross-sectional area of min.
0.5 mm² and max. 1.5 mm² for external on/off switch, digital in-
put, setpoint and sensor signals.
• The screens of the cables must be connected to frame at both
ends with good frame connection. They must be as close as
possible to the terminals, fig. 12.
Fig. 12
• Screws for frame connections must always be tightened
whether a cable is fitted or not.
• The wires in the pump terminal box must be as short as possi-
ble.
For the bus connection a screened 2-core cable must be used.
Connect the screen to terminal Y at both ends, fig. 13.
Fig. 13
8: +24 V
7: Sensor input
6: GND (frame)
5: +5 V
4: Setpoint input
3: GND (frame)
2: Start/stop
1: Digital input
A: RS-485A
Y: Screen
B: RS-485B
NC
NO Signal relay
C
L1
Mains
L2
connection
L3
Y