PPC3™ OPERATION AND MAINTENANCE MANUAL
© 2002-2007 DH Instruments, a Fluke Company Page 132
OPERATION
The procedure to adjust the output of the utility sensor is that same as for the calibration of an Internal, Hi (IH),
Standard Class, Q-RPT (see Section 5.2.1), but the calibration reference uncertainty can be between
0.01 and 0.05 % FS. To view/edit the calibration information for a utility sensor, use [SPECIAL], <8cal>,
<1Hi RPT>. The position designator of a PPC3 utility sensor is always <IuH>.
5.5 PNEUMATIC CONTROL MODULE CONFIGURATION
(<CONFIG>)
PURPOSE
To run an automated routine that automatically adjusts automated pressure control coefficients or to
return automated pressure control coefficients to factory default values.
PRINCIPLE
PPC3 uses factory configuration coefficients in the pressure control algorithms used for automated
pressure control. Changes in the pressure control elements over time or operation into an unusually
large test volume can cause pressure control performance to change. The PPC3 on-board configuration
routine automatically retunes the factory configuration coefficients to take these changes into account.
The CONFIG function should be considered a maintenance function and only used to attempt to improve
pressure control when all other factors affecting pressure control have been examined and eliminated (for
example leaks, restrictions in test lines, unstable pressure supply, unstable vacuum supply).
The configuration function may also be useful to speed up PPC3 pressure control when the minimum test
volume is in excess of 500 cc.
In addition, the CONFIG function allows pressure control parameters to be returned to factory default values.
This feature can be useful to return to known conditions after the on-board configuration function has been
run.
OPERATION
Poor control is usually caused by invalid control parameters, excessive leaks and restrictions in the
test system or other set up problems. These problems should be identified and eliminated before
resorting to use of the configuration function (see Section 6).
To access the CONFIG function press [SPECIAL], <7internal>, <1config>.
Select <2factory> to cause PPC3 to load factory default control coefficients. This feature can be useful
to return to standard conditions if a faulty CONFIG routine has been activated or the current configuration
is no longer valid.
Select <1run> to cause the pressure control module configuration routine to execute. Before running
CONFIG, remove any external volume and plug the TEST(+) port. However, if there is a minimum
anticipated test volume, for example, the G15K or BG15K DVU (see Section 2.3.8.2), leave the volume
connected. Connect the normal supply pressure to the rear panel SUPPLY port and perform a leak
check.
If the PPC3 Hi Q-RPT or utility sensor is an A350K or lower, the configuration routine should be run
twice, once with a vacuum source attached to the EXHAUST port and once without. If the PPC3 Hi
Q-RPT or utility sensor is greater than A350K, the configuration routine can be run with or without a
vacuum pump connected to the EXHAUST port (use your most common configuration).
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