Hardy HI 1756-FC - Manual (Page 29)

Rate Calibration Parameters
Three types of calibrations determine the flow rate per output percentage:
1. 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.
2. 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.
3. User-set rate calibration: Used when you cannot do an Auto RateCal and you
know the flow rate for all seven output percentage selections. If user-set
calibration is selected, you must manually enter the PI settings and the output %
and rate for all 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
rate.
RateCal Percents
RateCal Percents sets the output percentage for the three cal types.
1. 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.
2. For the 5 pt Cal Type (Pt1, Pt2, Pt3, Pt4, Pt5), each % should be > 10% different.
3. 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.
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Chapter 4 ●
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