IDEC FL1E SmartRelay - Manual (Page 48)

IDEC SmartRelay installation and wiring
34 IDEC SmartRelay Manual 
Circuit protection with AC voltage
To suppress voltage peaks on the power supply lines, you
can install a metal oxide varistor (MOV). Make sure the
operating voltage of the varistor (MOV) used lies at least 
20 % above the rated voltage.
2.3.2 Connecting the Text Display power supply
The Text Display must be connected to an external power
supply that supplies a voltage of 12 V DC or 24 V AC/DC. A
power connector is included with the Text Display.
 Power supply
 Communication interface
The power connection is non-polar. If you connect a DC
power supply to the Text Display, you can connect the
positive supply wire or negative supply wire to either the left
or right side.
Note
IDEC recommends that you protect the Text Display with a 0.5 A
safety fuse on the power supply.