Flowserve NRS 1-50 For TWO Electrodes - Manual (Page 14)

4
Electrical Connection
– continued –
Tools
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Screwdriver for slotted screws, size 3.5 x 00 mm, completely insulated according to VDE 0680-.
Danger
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For the supply of the level switch NRS -50 with 4 V DC use a safety extra-low
voltage (SELV) power supply unit that must be electrically isolated from dangerous
contact voltages and must meet at least the requirements on double or reinforced iso-
lation acc. to DIN EN 5078 or DIN EN 600- or DIN EN 60730- or DIN EN 60950
(safe isolation).
n
Any item of equipment that you want to connect to terminals 6, 7, 4, 5 (standby
input  / ) must be certified to have at least double or reinforced isolation according
to DIN EN 5078 or DIN EN 600- or DIN EN 60730- or DIN EN 60950 (safe
isolation) between the standby inputs and the live parts of the installation that are not
supplied with safety extra-low voltage (SELV).
Attention
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Provide the level switch NRS -50 with an external semi-delay fuse 0.5 A.
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Connect screens of electrode wires only to terminals 5 and 3.
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To protect the switching contacts provide the safety circuit with a slow-blow fuse  A
or .0 A (for 7 hrs. operation acc. to TRD 604).
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When switching off inductive loads, voltage spikes are produced that may impair
the operation of control and measuring systems. Connected inductive loads must be
provided with suppressors such as RC combinations as specified by the manufacturer.
n
When used as water level limiter according to TRD, EN 95 / EN 953 connect
terminals 4 and 6 by adding a wire link.
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Install connecting lines to level electrodes and logic unit separated from power cables.
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Do not use unused terminals as support point terminals.