Teledyne Analytical Instruments 3020 M, Руководство по эксплуатации

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Operational Theory Model 3020M-ATEX
Teledyne Analytical Instruments 18
2.5 Electronics and Signal Processing
The Model 3020M Percent Oxygen Analyzer uses an 8031
microcontroller with 32 kB of RAM and 128 kB of ROM to control all
signal processing, input/output, and display functions for the analyzer.
System power is supplied from a universal power supply module
designed to be compatible with most international power sources. See
chapter
5 Maintenance for the location of the power supply and the main
electronic PC boards. The Paramagnetic Sensor has its own dedicated
universal 24V power supply that feeds the sensors internal heater and
electronics.
The signal processing electronics including the microprocessor,
analog to digital, and digital to analog converters are located on the main
PCB, on the front door (see figure 5-1). The preamplifier board is
mounted on top of the motherboard. These boards are accessible by
opening the front door of the explosion proof enclosure. Figure 2-4 is a
block diagram of the Analyzer electronics.
In the presence of oxygen the chamber is rotated in the magnetic
field, but the cell generates a current to counter torque the oxygen
action. This current is converted to a voltage, which is preamplified in
the sensor internal electronics.
The preamplified signal (0-1 Volt) is fed to the 3020M amplifier
for minor processing.
The digital concentration signal along with input from the control
panel is processed by the microprocessor, and appropriate control
signals are directed to the display, alarms and communications port. The
same digital information is also sent to a 12 bit digital to analog
converter that produces the 4-20 mA DC and the 0-1 V DC analog
concentration signal outputs, and the analog range ID outputs.
Signals from the power supply are also monitored, and through the
microprocessor, the system failure alarm is activated if a malfunction is
detected.
2.6 Temperature Control
For accurate analysis the standard sensor temperature is controlled
internally at 55°C. This is set at the factory. The 0-1% sensor is installed
in an oven and uses a PID temperature controller to control the
temperature of the sensor. It is also set at the factory prior to shipping
but can be altered by the user.