23
NRS 1-50 For TWO Electrodes - Installation Instructions -
818953-08
Action against high frequency interference
Should sporadic failures occur in installations susceptible to faults (e. g. malfunctions due to out-of-
phase switching operations) we recommend the following actions in order to suppress interferences:
n
Provide inductive loads with RC combinations according to manufacturer's specification to ensure
interference suppression.
n
Make sure that connecting cables leading to the level electrodes are segregated and run separately
from power cables.
n
Increase the distance to sources of interference.
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Check the connection of the screen to the central earthing point
(CEP)
in the control cabinet.
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HF interference suppression by means of hinged-shell ferrite rings.
Further Notes
n
Switch off mains voltage and
cut off power supply
to the equipment.
n
Unscrew the right and left fixing screws
3
and remove the upper and lower terminal strips
1 2
,
Fig. 6
n
Release the white fixing slide at the bottom of the equipment and take the equipment off the
supporting rail.
Decommissioning / replacing level switch
Disposal
For the disposal of the level switch observe the pertinent legal regulations concerning waste disposal.
In the event of an alarm the level switch NRS 1-50 does not interlock automatically.
If a lock function is required by the installation it must be provided in the follow-up circuitry (safety
circuit). The circuitry must meet the requirements of the EN 50156.
Interlock and interlock deactivation
To check the switchpoint “Low water (LW)” you have to lower the water level. When the water level
falls below the electrode tip, the level switch must activate an alarm and the safety circuit must open
as soon as the de-energizing time delay has elapsed. The switching-off of the heating is interlocked in
the safety circuit and can only be deactivated when the level electrode enters the water again. In this
case the LEDs for alarm 1 and 2 must be illuminated and no malfunction must be indicated (diagnosis
LEDs are not illuminated). Always check the switchpoint when commissioning the equipment, after
replacing the level electrode and at regular intervals, e.g. every year.
Checking the switchpoints
