DH Instruments PPC4, Руководство по эксплуатации и обслуживанию

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3. OPERATING PRINCIPLES
Page 29 © 2009 DH Instruments, a Fluke Company
Gauge Measures pressure relative to atmosphere (zero is ambient pressure).
Range is from zero gauge to full scale, full scale must be greater than zero.
Negative gauge Measures pressure relative to atmosphere (zero is ambient pressure).
Values are positive and negative, with ranges from negative one
atmosphere to positive full scale. With a BGxxx Q-RPT, negative full scale
is the negative equivalent of positive full scale.
Which measurement modes are available depends on the type(s) of Q-RPT available. There are
three Q-RPT types:
Axxx Q-RPTs with designators starting with “A” measure pressure relative to a sealed
vacuum reference and are intrinsically absolute. Axxx Q-RPTs support
measurement in absolute, gauge and negative gauge modes. Gauge and negative
gauge modes are accomplished by PPC4’s automated offsetting of atmospheric
pressure and dynamic compensation for atmospheric pressure changes between
offsets using an on-board barometer (see Section 3.2.4). Access to absolute and
negative gauge operation can be turned OFF if these modes are not used (see
Section 7.2.5).
Gxxx Q-RPTs with designators starting with “G” measure positive pressure relative to the
TEST(-) port that is connected to atmosphere. Gxxx Q-RPTs support
measurement in gauge mode only.
BGxxx Q-RPTs with designators starting with “BG” measure positive and negative pressure
relative to the
TEST(-) port that is connected to atmosphere. BGxxx Q-RPTs support
measurement in gauge and negative gauge modes.
When changing measurement modes for a range, if the full scale of the range is 700 kPa
(100 psi) or greater, the full scale is the same in both absolute and gauge modes. If the full
scale is less than 700 kPa (100 psi), the gauge mode full scale is 100 kPa (14.5 psi) lower
than the absolute mode full scale. Gauge and negative gauge mode, when available, have the
same full scale.
Note
•
Certain PPC4 settings, including AutoZ ON/OFF (see Section 3.2.22) are
range AND measurement mode specific. See Table 4 for a listing of
settings and what they are specific to.
•
Absolute and negative gauge modes on an Axxx Q-RPT can be turned
OFF in the calibration function (see Section 7.2.5). When absolute and
negative gauge mode are turned OFF for an Axxx Q-RPT, only gauge
mode can be activated.

OPERATION
For Basic Interface see Section 4.5.15.
For Advanced Interface see Section 5.7.6.2.
3.2.12 Set Pressure Automatically

PURPOSE
To use the automated pressure control functions of PPC4 to set and maintain target pressure
values.

opens the target screen to initiate the sequence.