DH Instruments PPC4, Operation And Maintenance Manual

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PPC4™ OPERATION AND MAINTENANCE MANUAL
© 2009 DH Instruments, a Fluke Company Page 202
7.9.1 Power Supply Module
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+ 12 V DC (± 2 %) @ 3.3 Amps: For internal and external valve actuation.
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+ 5 V DC (± 1 %) @ 3.0 Amps; + 15 V DC (± 3 %) @ 1.5 Amps; - 15 V DC (± 3 %)
@ 0.35 Amps: For the supply of the micro board and driver board electronics.
7.9.2 PowerPC Board
The PowerPC board supports a Motorola PowerPC 8241 processor, EPROM, EEPROM,
128k x 8 bit NVRAM, 64 Mbit flash memory, 256 Mbit SDRAM memory; RS232
communications; and display control. An FPGA controls other ports and devices in PPC4.
7.9.3 Q-RPT MODULE
The Q-RPT module is an integrated assembly that mechanically manages the PPC4’s
pressure transducers. The module includes a Hi Q-RPT (quartz reference pressure
transducer) or utility sensor and may also have a Lo Q-RPT, brackets to hold the
transducer(s) interconnecting tubing, a manifold with the PPC4’s
TEST (-) , TEST(+) and
VENT ports and solenoid valves for AutoZeroing, measurement mode changes and switching
of the active transducer.
See Figure 32 for pneumatic schematics of different Q-RPT module configurations.
7.9.3.1 Hi Q-RPT or Utility Sensor
The higher range pressure transducer in a PPC4 may be a Q-RPT (quartz reference
pressure transducer) or a utility sensor depending on the specified PPC4 configuration.
A Q-RPT is intended to provide very high precision, low uncertainty, traceable
pressure measurement. The basic sensing principle is the measurement of the
change in the natural oscillating frequency of a quartz tuning fork in response to
changes in temperature and mechanical stress resulting from the change in
pressure applied to a connecting bellows or bourdon tube. Two independent quartz
elements are used. One quartz element is subjected to pressure related stress.
The other quartz element is used only to monitor temperature. See Section
1.2.2.1 for Q-RPT specifications.
The utility sensor is for pressure indication, safety and housekeeping functions.
It is a temperature compensated micro-machined silicon sensor module.
7.9.3.2 Lo Q-RPT
PPC4 may be equipped with a Lo Q-RPT. The Lo Q-RPT provides a lower
measurement range than the Hi Q-RPT or utility sensor. See Section 7.9.3.1 for
a description of Q-RPTs and Section 1.2.2.1 for complete Q-RPT specifications.
7.9.4 On-board Barometer
The on-board barometer supports a board mounted, barometric range, micromachined silicon
sensor and an ambient temperature sensor. The barometer readings are used for dynamic
atmospheric pressure compensation when measuring gauge pressure with an absolute
reference transducer (see Section 3.2.4). The temperature sensor is used for temperature
compensation of the barometric sensor.
Note
PPC4s that have Gxxx Q-RPTs (no Axxx, BGxxx or utility sensor) are NOT
equipped with an on-board barometer.