PRESYS
Instruments
T-650PH
Page 21
Input calibration for
is performed in two steps:
a) Application of mV signal:
For the calibration below, leave terminals RTD3 (+) and RTD4 (+) short-circuited.
mV Signal
Terminals
1
st
point
2
nd
point
V_OHM3
RTD3(+) and mV(-)
90.000 mV
120.000 mV
V_OHM4
RTD4(+) and mV(-)
90.000 mV
120.000 mV
b) Application of standard resistors:
Connect a decade box or standard resistors on terminals RTD1, RTD2, RTD3 and
RTD4 (4-wire connection).
resistors
1
st
point
2
nd
point
OHM3
20.000
50.000
OHM2
100.000
500.000
OHM1
500.000
2200.000
The cold junction calibration (CJC) is performed measuring the mV(-) terminal
temperature. Store only the 1
st
point.
Cold Junction
1
st
point
CJC
32.03 °C
7.2 - Probe Calibration
The options of calibration / probe are:
°C
RESTORE
°C
: Adjust of the internal temperature sensor (internal Probe).
RESTORE
: Restores the internal temperature sensor calibration parameters to
the factory values.
To readjust the internal Probe it is necessary to compare the value indicated by
the calibrator (Probe) and the temperature value from an external probe placed in the dry
block insert. The temperature of the external probe should have high accuracy and
should be measured by a superthermometer (ST).
The option to adjust the internal sensor has seven points of adjustment. These
points are recorded via keys 1 to 7.
Before starting the calibration (adjustment), record in these points the respective
initial storing values, according to the table below.
Go to the manual operating mode (menu
EXEC
) and generate all the seven levels
of temperature (setpoints from the table), writing down the value indicated by the
superthermometer (ST). Now, go back to the option Calibration/ Probe / °C and record
the values indicated by the superthermometer.
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