Page 54 of 101 pages
5. CALIBRATION
The calibration of temperature and pressure is performed digitally.
The temperature and pressure measuring circuits are designed with
components having a 1% precision. The temperature circuit is linear and has
an output of 100mV-2400mV for a temperature range of 20
º
C-150
º
C.
The pressure circuit is also linear and has an output of 100mV-2400mV for a
pressure range of 0-400kPa.
The measuring at the A/D is void for values higher than 2400mV or lower
than 100mV.
Even though the precision of the components of the circuit is 1%, the
acceptable deviation can reach
±
5%, therefore calibration is necessary.
The system has a non-erasable memory in which the offset and gain data of
the sensors are stored.
This data may be inserted to the system, through programming or through
the autoclave.
In this chapter we shall describe the calibration of temperature and pressure
through the autoclave, the programming calibration procedure is altogether
identical.
The calibration method enables to insert this data into the system in order to
perform the automatic correction of the OFFSET and GAIN.
It is recommended to find the two points which have to be inserted to the
system, before performing the calibration.
a
X
Y
INPUT FROM SENSOR
PRESUR
E
V
1
310
30
V
2
100
90
READ
ACTUAL
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