19
NRS 1-51 - USA - Installation & Operating Manual -
850695-00
Electrical connection
Connecting the level electrode
Please use the following to connect the level electrode:
■
For an NRS 1-51 level switch with a response sensitivity of 5 ppm (10 µS):
Use a shielded, multi-core TC-ER control cable with minimum wire size AWG18, e.g., OELFLEX
CONTROL TM CY 5G1. Max. length 328 ft (100 m).
Wire the terminal strip as shown in the wiring diagram.
Fig. 4.
Connect the shields to terminal 5
and to the central grounding point
(CGP)
in the control cabinet.
Please connect the control circuit for the feedwater supply/heating to terminals 23, 24 and 26,
27. If you are using the equipment as a high level alarm, please connect the output contacts of
the two monitoring channels by adding a wire jumper between terminals 24 and 26.
Provide the output contacts with a slow blow T1A fuse.
Connecting the control circuit
Note
■
A high level alarm prevents the defined high water level from being exceeded. To
achieve this, the feedwater supply may be cut, for example. If cutting the feed-
water supply poses a danger to heating surfaces in the feedwater pre-heater, the
heating must be switched off as well.
■
In the event of an alarm, the NRS 1-51 level switch interlock does not take place
automatically.
If the installation requires an interlock, this must be implemented in the down-
stream (control) circuit.
■
In order to guarantee Class C function with second fault protection in accordance
with UL 60730-1, both signaling outputs must be monitored during interlock
deactivation.
■
It is important that the interlock is not deactivated when the level switch signals
a malfunction to the diagnostic LEDs or the signaling outputs.
Supply voltage
Please provide the NRS 1-51 level switch with an external 0.5A fuse.
