13
NRS 2-50, NRS 2-51 - Installation & Operating Manual -
819179-05
In the control cabinet: Wiring the level switch
The equipment is supplied with 24 V DC and has an external 0.5A semi-delay fuse. Please use a safety
power supply unit with reliable electrical isolation.
This power supply unit must be electrically isolated from dangerous live voltages and meet the require-
ments for double or reinforced insulation in accordance with one of the following standards:
DIN EN 50178, DIN EN 61010-1, DIN EN 60730-1 or DIN EN 60950.
Connecting the level electrode/level transmitter
To connect the equipment, please use a shielded, multi-core control cable with a minimum conductor
size of 0.5 mm
2
, e.g. LiYCY 4 x 0.5 mm
2
, maximum length 100 m.
Max. three NRS/NRR 2-5.. switches/controllers can be connected to one level electrode or one level
transmitter.
Wire the terminal strip as shown in the wiring diagram.
Fig. 3, 4
Connect the shield as shown in the wiring diagram.
Route the connecting cable between items of equipment separately from power lines.
Supply voltage connection
Connecting the output contacts
Wire the upper terminal strip
1
(terminals 16-23) in line with the desired switching functions.
Provide an external 2.5A slow-blow fuse for the output contacts.
Switching off inductive loads produces surges that can have a major adverse effect on the operation
of open and closed-loop control systems. Connected inductive loads must therefore have interference
suppression (RC combination) as per the manufacturer's specifications.
Tools
n
Screwdriver size 3.5 x 100 mm, fully insulated to VDE 0680-1.
Attention
n
Do not use unused terminals as support terminals.
Connecting the actual value output
For connection, please use a shielded, multi-core control cable with a minimum conductor size of
0.5 mm
2
, e.g. LiYCY 2 x 0.5 mm
2
, maximum length 100 m.
Please note the maximum output load of 500 ohms.
Wire the terminal strip as shown in the wiring diagram.
Fig. 3, 4
Connect the shield
once
only
to the central earthing point (CEP) in the control cabinet.
Route the connecting cable between items of equipment separately from power lines.
Any item of equipment that you wish to connect to the terminals for the 4-20 mA actual value output
must be certified to have at least double or reinforced insulation to DIN EN 50178 or DIN 61010-1 or DIN
EN 60730-1 or DIN EN 60950 between the current loop and live parts of the equipment that are not
supplied with safety extra-low voltage (SELV).
continued
