Teledyne 3010MA, Руководство по эксплуатации, Страница: 22 / 88

Part 1 Control Unit Model 3010MA
Teledyne Analytical Instruments
22
When an oxygen level above 95% is present, the paramagnetic sensor
in the Analysis Unit generates a voltage. The voltage is passed to the
Control Unit via the sensor cable between the Analysis Unit and the
Control Unit. A voltage amplifier in the Control Unit conditions the signal
and passes it to the 18-bit analog to digital (A/D) converter which is
controlled by the microprocessor.
The sensor’s vent pressure from the Analysis unit is received via a 1/8
inch gas connection on the rear of the control unit. The vent pressure is
then routed to the pressure transducer located on the pre-amp PCB. The
output from the sensor is condition by a two-stage amplifier and passed to
the A/D converter.
The concentration signal, pressure signal, and the input from the
control panel are 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.
The microprocessor monitors the power supply, and activates the
system failure alarm if a malfunction is detected.
2.5 Temperature Control
For accurate analysis this instrument is temperature controlled to
provide a thermally stable environment. The analyzer must be brought to
thermal equilibrium prior to analyzing any sample gas. The paramagnetic
sensor is sensitive to operating temperature variations. The sensor module
used in the Model 3010MA includes a pre-amp and an internal
temperature controller set to 55
°
C. The sensor module is also housed in an
insulated temperature controlled oven within the Analysis Unit to improve
thermal stability and isolate the system from any external temperature
fluctuation. The oven temperature is maintained at a constant 40
°
C by the
PID temperature controller located in the Control Unit (see Figure 2-3).
Feedback to the temperature controller is by an RTD
on the sensor
mounting block. The oven is capable of providing a maximum of 80
Watts.