21
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.
n
Check the connection of the screen to the central earthing point (CEP) in the control cabinet.
n
HF interference suppression by means of hinged-shell ferrite rings.
Further Notes
n
Switch off supply 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
Undo the fixing slide in order to snap out the level switch and take it off the supporting rail.
Decommissioning / replacing level switch
Disposal
Remove the level switch and separate the waste materials in accordance with the material
specification.
Electronic component parts such as the circuit board must be disposed of separately!
For the disposal of the levels switch observe the pertinent legal regulations concerning waste disposal.
In the event of an alarm the level switch NRS 1-51 does not interlock automatically.
If a lockout function is required by the installation it must be provided in the follow-up circuitry (control
circuit). The circuitry must meet the requirements of the EN 50156.
Interlock and interlock deactivation
To check the switchpoint “High water level (HW) exceeded” you have to fill the boiler until the max.
water level is reached. As soon as the high level is reached the level switch must trigger an alarm and
open the control circuit after the de-energizing delay has elapsed The deactivation of the heating is
interlocked in the control circuit and the lockout can only be reset when the level electrode is exposed
again. Always check the switchpoint when commissioning the equipment, after replacing the level
electrode and at regular intervals, e. g. every year.
Checking the switchpoints
Содержание NRS 1-51
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