14
Electrical Connection
NRS 1-8
Cable required for wiring the electrode: four-core screened cable, e. g. I-Y(St)Y 2 x 2 x 0.8 or
LIYCY 4 x 0.5 mm
2
.
Max. cable length 100 m with a conductivity from 10 µS/cm.
Max. cable length 30 m with a conductivity from 0.5 µS/cm.
Max. cable length 15 m with a conductivity from 0.5 µS/cm when used in conjunction
with ancillary unit URN 1 (24 V DC).
Tools
n
Screwdriver for slotted screws, size 2.5, completely insulated according to DIN VDE 0680-1
Voltage table
Use this voltage table as reference when checking the level electrode for malfunctions or submersion.
Please observe the wiring diagram for NRS 1-8.
Fig. 10, Fig. 11
Attention
n
To protect the switching contacts provide circuit with a 2.5 A slow-blow fuse or
according to TRD regulations (1.0 A for 72 h operation).
n
The screen must not make any other electrical contact
Notice
n
The self-checking routine of the level switch NRS 1-8 reduces
U
1-2
all 40 seconds to
zero volt.
n
Connect screen only to terminal 8 of the level switch.
n
The sensitivity of response is indicated on the name plate.
n
The rated voltage is indicated on the name plate.
n
When switching off inductive loads, voltage spikes are produced that may impair the
operation of control and measuring systems. Inductive loads should be provided with
commercial arc suppressor RC combinations, e.g. 0.1 µF/100 W.
U
1-2
U
1-2
10 µS/cm
0.5 µS/cm
2 V
eff
C=0.3 cm
-1
10 V
eff
C=0.13 cm
-1
