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FCB100, FCB400 COMMISSIONING AND PROVING | PG/CORIOLIS/PROVING-EN REV. A
3 Frequency output configuration
1 No modification required, default is 'Forward'
Digital out 41 / 42 mode:
Digital out 41 / 42 output value:
Upper frequency:
Figure 2: Digital output configuration (41 / 42) as frequency output
Change from one to two columns
Please make sure that there are always sufficient pulses per
proving cycle. Ideally there should be 10,000 or more pulses per
proving cycle.
Note
Care should be taken when selecting the values to ensure that
the following two conditions are satisfied.
When measuring medium is flowing through the flowmeter at
maximum operational flow rate – the frequency output by the
flowmeter should neither exceed 90 % of its rates maximum nor
90 % of the maximum rated input frequency of the tertiary
devices receiving the signal.
Upper frequency calculation example
The upper frequency should be calculated in the following way:
Upper frequency = (Qv
max
Legend
Qv
Maximum flow in your application
max
T
Factor to calculate the chosen Qv
second
N
Number of pulses per flow unit as configured in the receiving
device (flow computer or prover counter)
Change from one to two columns
Frequency
Volume flow
See calculation below
/T) × N
unit down to a unit per
max
Example bbl/day:
(5000 bbl/day / 86400 s/day) × 10000 pulses/bbl
= (5000 / 86400) × 10000/s
Upper frequency = 579 Hz
Example bbl/hr:
(300 bbl/hr / 3600 s/hr) × 20000 pulses/bbl
= (300 / 3600) × 20000/s
Upper frequency = 1666,67 Hz
Note
Ensure that the resulting 'upper frequency' factor is within
reasonable limits.
•
If it is less than 10 Hz, choose more pulses per unit 'N'.
•
If it is greater than 10000 Hz, choose less pulses per unit 'N'.
Other digital output configuration (e.g. pulse output) are shown
in Appendix – Pulse output configuration on page 12.
5
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