12
SRL 6-60 - Installation & Operating Manual -
819698-00
Function
Operating principle
Fig. 4
shows a water level limiter system with one level electrode in the boiler and the second electrode
in an external level pot.
The following combination is also possible, however:
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2 x NRG 1x-6x level electrode, external
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2 x SRL 6-60 monitoring logic unit
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1 x URS 60 or URS 61 safety control unit
The SRL 6-60 monitoring logic unit monitors the following times:
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Interval time
This is the interval at which, depending on the operating mode (e.g. 24 h/72 h operation), the con-
necting pipes must be flushed.
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Standby time
The purging process must be initiated within this time. The standby time begins after the interval has
elapsed.
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Purge time (safety-relevant function)
The purging process must be initiated by valve actuation within this time. Valve actuation and expo-
sure of the LW level electrode (electrode tip no longer submerged) are indicated by the limit switches.
The start of the purge time was also sent to the URS 60 / URS 61 safety control unit, and runs parallel
to the SRL purge time. If a signal is not received within the purge time, the safety circuit opens. As a
water level limiter can only be bridged for a maximum of 5 minutes, monitoring of the purge time is
relevant to safety.
URS 60 / URS 61 safety
control unit
Safety circuit
SRL 6-60
Electrode 1
NRG 1x-6x
Electrode 2
NRG 1x-6x
Fig. 4
