Fluke Calibration 4322-SYS-NAVAIR, Service Manual

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4322
Service Manual
2-4
Pressure Control
The Controller offers three different control modes to set pressure: Static Mode sets the
target pressure and stops controlling, adjusting only when the measured pressure has
exceeded specific limits. Dynamic Mode sets the target pressure and constantly adjusts to
maintain the target. Dynamic Control with Jog Approach uses the same control as
Dynamic Mode, but pressure is set to a point short of the test point. The user then uses
the jog function to adjust pressure to the desired UUT reading.
The control modes are set in the settings and also as part of a test. If a target pressure is
set on the Main menu, the Controller uses the control parameters in the settings. If a test
is run, the Controller uses the control parameters saved in the test. The two modes have
similar control parameters but control pressure differently. See the 4322 Operators
Manual for more information on the control modes.
Note
When a test is run, the Controller temporarily switches to the test settings
for the duration of the test. After the test is complete, the Controller
automatically reverts back to the system settings.
In addition to the control modes, the Controller has two pressure limits that the user can
set in the Settings menu or in the Test menu:
•
The
upper and lower pressure limits
are user configurable protective pressure
limits that protect the UUT from accidental overpressure. The limits are used when
the target pressure is manually set from the Main menu. If the target pressure entered
is more than the upper limit or less than the lower limit, the Controller will not accept
the target pressure value and displays an out of range error message.
•
The
control hold limit
is a symmetrical positive and negative range of pressure
above (upper hold limit) and below (lower hold limit) the target. The Controller does
not let the applied pressure go outside the hold-limit range. The hold limit is used to
determine the “Ready” condition in dynamic control mode. Static control mode uses
a combination of the hold limit and stability limit to determine the “Ready”
condition. The hold-limit ranges are different for each mode.
Note
When a Test Sequence is run, the Controller automatically vents
excess pressure to protect the UUT whenever pressure greater than
110 % of the UUT full scale range is sensed. No manual setting of
upper limit or other settings is necessary to engage this protection.
See the 4322 Operators Manual for more information on the pressure limits. Read the
subsequent sections to learn how the Controller uses the different valves to internally
control pressure. Each valve has a reference designator that is used throughout this
chapter. Figure 2-1 is an illustration that shows where each of the valves are physically
located. Figure 2-2 shows a schematic of the isolation valves, solenoids, piezo-electric
valves in the Controller. Table 2-1 shows the configurations of the isolation valves,
solenoids, and piezo-electric valves at different phases or pressures.