11
In control cabinet: Wiring level electrode
- continued -
Connecting supply voltage
The equipment is supplied with 24 V DC and fused with an external semi-delay fuse 0.5 A.
Please use a safety power supply unit with safe electrical isolation.
The power supply unit must be electrically isolated from dangerous contact voltages and must meet at
least the requirements on double or reinforced isolation according to one of the following standards:
DIN EN 50178, DIN EN 61010-1, DIN EN 60730-1 or DIN EN 60950.
Connecting MIN 1 / MIN 2 output contact
Wire the upper terminal strip
1
(terminals 16-18, 21-23) according to the desired switching functions.
If only one electrode rod is used please connect the terminals 17 and 23 (safety circuit) and the termi-
nals 6 and 7 with a wire link.
Fig. 3
Provide an external slow-blow fuse 2.5 A for the output contacts.
When used as water level limiter the level switch NRS 1-53 does not interlock automatically when the
water falls below the MIN level.
If an interlock function is required for the installation it must be provided in the follow-up circuitry
(safety circuit). The circuitry must meet the requirements of the EN 50156.
When switching off inductive loads, voltage spikes are produced that may impair the operation of con-
trol and measuring systems. Connected inductive loads must be provided with suppressors such as RC
combinations as specified by the manufacturer.
Connecting level electrode
To connect the level electrode(s) use screened multi-core control cable with a min. conductor size
0.5 mm
2
, e. g. LiYCY 4 x 0.5 mm
2
, max. length: 100 m.
Wire terminal strip in accordance with the wiring diagram.
Fig. 3
.
Connect the screen
only
once
to the central earthing point (CEP) in the control cabinet.
Make sure that connecting cables leading to the level electrodes are segregated and run separately
from power cables.
Tools
n
Screwdriver for slotted screws, size 3.5 x 100 mm, completely insulated according to VDE 0680-1.
Attention
n
Do not use unused terminals as support point terminals.
