WET WELL FAILSAFE
OPERATION
For this example we’ll assume:
P001 Operation is set to "level" (P001 = 1).
P003 Measurement Response is set to "medium" (P003 = 2, preset).
P006 Empty is set for 6.000 metres.
P007 Span is set for 5.000 metres.
P071 Failsafe Material Level is set for "HI".
P100 Relay Set Up is set for Wet Well 1 (P100 = 1).
a) high alarm is to indicate failsafe operation.
b) lead pump starts (as preset) at 70% (3.5 m).
c) high alarm trips on (as preset) at 90% (4.5 m) and off at 85% (4.25 m).
d) normal wet well filling rate is 0.3 m/minute.
e) back up system takes over if level reaches 5.5 m.
f) at 9:15 am, the HYDRO+ transducer cable was accidentally cut.
e.g. 09:15:00 am Echo lost at 2.2 m, pump(s) turn off, countdown begins
09:25:00 am Failsafe activated, reported level advances at 1 m/min (P003).
09:26:00 am backup control takes over, actual level = 5.5 m (and falling).
09:27:18 am HI alarm trips on, reported level = 4.5 m.
09:27:48 am HI alarm still on, reported level = 5 m.
HI Level
Fault
Detector
LO Level
Fault
Detector
APPLICATIONS
PL-507 59
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