Hardy HI 1769-FC - Manual (Page 46)

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Chapter 4
Rate Calibration Parameters
Three types of calibrations determine the flow rate per output percentage:
Two-point rate calibration: Used for Auto RateCal. If a two-point Auto Rate
Calibration is selected, two flow rate points (points two and four) are used for calculating
other rate point values. The unit will go to the high rate output percent for a period of
feed time plus prime time (See parameters E and 10 above). When this period is
complete, it saves the actual rate as the high cal rate, then pauses for a period of pause
time (See parameter F) before going to the low rate output percent for a period of feed
time. When this period is complete, it will save the actual rate as the low cal rate. After
doing the auto rate calibration at the low and high rates, the unit will estimate the zero
rate output percent and the Max rate cal rate and will fill values for the first, third, and
fifth five-point calibration rate pairs.
Five-point rate calibration: Five-point measurement used with Auto RateCal to provide
tighter flow rate control. The user enters the output percent values, and the unit then runs
at each of these output percents, starting with the highest one, for a period of feed time or
feed time plus prime time on the first run. It saves the actual rates it observes into the cal
rates and estimates the MaxRate and zero output rates.
Advanced calibration: Used when you cannot do an Auto RateCal and you know the
flow rate for two output percentage selections. If advanced calibration is selected, you
must manually enter the output % and rate for the second and fourth calibration pairs.
The entered flow rates can come from experience with the material, often through trial
and error. We recommend that you select output percentage points where your expected
control set point falls between point two and point four.
Configuring Rate Calibration
NOTES Make sure you have enough material to do a Rate Cal at the highest OP%. If, for
example, 30 seconds at 90% would empty the hopper, reduce the Rate Cal to a lower
percent.
RateCal Percents
RateCal Percents sets the output percentage for the three cal types.
For the 2 pt Cal Type (%Lo & % Hi), make sure that the Hi % is higher than the Lo %
and that there is a separation of at least 10%. You enter Pt2 and Pt4.
For the 5 pt Cal Type (Pt1, Pt2, Pt3, Pt4, Pt5), each % should be > 10% different.
For the User-set cal Type, you need to know the flow rates for all output percentage
setpoints. You enter the output percentages and the known flow rates and the correct PI
setting.
Range: 0 -100
You can edit other parameters, including adjustable values in the OP% (and/or Cal Rate)
fields.
Example: A calibration pair Output percent of 25% and a cal rate 250 means that a rate of
250 weight units per unit time will be obtained when the output percent is 25 %.
Running Rate Cal
The user enters all OP percentages. The Auto Rate Cal will prime the system then run for
the selected feed time based on the calibration type, pause time, and RateCal Percents
you selected.
For the 2 pt Cal Type (Pt2 and Pt4), the two flow rates for the percentages you selected
are the actual flow rates. The instrument calculates the remaining three flow rates.