Example 5
The application is to monitor the differential level across a sewage bar screen. When a
differential level of greater than 12” is obtained, it is required that a rake be started. If
the water level on either side rises above 20", a high level alarm is required.
The height from the common (low) level to the transducer face is 4 ft. A 4 - 20 mA
output corresponding to the differential is required and the 20 mA level has been
arbitrarily set to correspond to a 24" differential (span). In the event of a loss of echo,
the HydroRanger I should go into fail-safe high after 5 minutes.
select:
P-1 enter option “4”, units in inches
P-2 enter option “3”, differential level
P-3 enter “48”, empty distance to transducer
P-4 enter “24”, span
P-5 enter “16”, near blanking distance, 48" - (12" + 20") = 16"
P-6 enter option “2”, 4 - 20 mA output
P-7 enter “1”, display max. 1 digit after decimal
P-8 enter option “4”, relay 1 - differential alarm
P-9 enter “12”, relay 1 - rake on
NOTE: This would be used only to initiate the rake control
circuitry.
P-10 enter “6”, relay 1 - reset this value can be arbitrarily set
P-11 enter option “1”, relay 2 - alarm function
P-12 enter “20”, relay 2 - alarm ON
P-13 enter “19”, relay 2 - alarm OFF
P-20 enter option “14”, relay 5 - scanner
P-32 enter option “1”, mA output on differential
P-68 enter “393.7”, fill damping 393.7 in/min. Normally this level would rise over
a period of days or weeks, therefore damping requirements
would be fairly low. Typically, the factory set damping of
32.81 can be used.
P-69 enter “393.7”, empty damping - same as fill damping
P-74 enter option “1”, fail-safe high
P-75 enter “5”, fail-safe timer
press:
to re-enter run mode
RUN
CAL
PL-399 6 – 26
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