One Point Calibration Method; Two Point Calibration Method - ILX Lightwave Temperature Controller LDT-5525 User Manual

C
C H A P T E R

One Point Calibration Method

This procedure will work for any linear temperature sensor. The accuracy of this
procedure depends on the accuracy of the known temperature, externally
measured. It is used to determine the zero offset of the device, and it assumes
that the gain offset (slope) is known and is correct.
1
2
3
4

Two Point Calibration Method

This procedure will work for any linear temperature sensor. The accuracy of this
procedure depends on the accuracy of the known temperatures, externally
measured. It is used to determine the zero offset of the device and the gain offset
(slope).
1
2
3
4
5
40
LDT-5525
Allow the LDT-5525 Temperature Controller to warm up for at least one hour. Set the
SENSOR SELECT switch for the desired sensor type, and RECALL the constants for the
particular device to be calibrated.
Select the C1 parameter. Read and record the value of C1.
Place the sensor at an accurately known and stable temperature, T
to pins 7 and 8 of the LDT-5525's 15-pin connector. Set the LDT-5525 for normal constant
temperature (T mode) operation. Allow the LDT-5525 Temperature Controller to stabilize
at the known temperature, Ta and read the displayed temperature, Td.
Determine the new value of C1, C1
C1 = C1 + T - T
n a d
and replace C1 with C1 by selecting the C1 parameter and entering the new C1
n
Allow the LDT-5525 Temperature Controller to warm up for at least one hour. Set the
SENSOR SELECT switch for the desired sensor type, and RECALL the constants for the
particular device to be calibrated.
Select the C1 parameter. Read and record the value of C1. Select the C2 parameter.
Read and record the value of C2.
Place the sensor at an accurately known and stable temperature, Ta1. Connect the
sensor to pins 7 and 8 of the LDT-5525's 15-pin connector. Set the LDT-5525 for normal
constant temperature (T mode) operation. Allow the LDT-5525 Temperature Controller to
stabilize at the known temperature, Ta1 and read the displayed temperature, T
these values.
Repeat Step 3 for another known temperature, T
temperature, T .
d2
The two known temperatures should at the bounds of the intended operating range. The
smaller the intended operating range, the better the calibration over that same range.
Determine the new value of C1 (C1
First determine the intermediate values U and V, where
, from the formula:
n
, and the corresponding displayed
a2
) and C2 (C2 ) from the following calculations.
n n
. Connect the sensor
a
value.
n
. Record
d1