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4.2 “TCM” - Temperature Compensated Measurement Mode
Valhalla Engineers are pioneers in the technology of accurate measuring devices using
recognized formulas that compensate for measurement inaccuracies as a result of
environmental changes. The TCM feature simulates a constant ambient temperature
chamber for materials which are normally subject to varying ambient temperatures. When in
the TCM mode, the temperature sensor, the Omni Compensator, automatically senses the
ambient temperature and compensates the reading to indicate what the actual resistance
value should be in a controlled environment (usually 20°C). The compensated value is
calculated with the following equation:
T
R
R
∆
=
∆
α
0
The variation of resistance (
∆
R) divided by the initial resistance (R
0
), is equal to the
temperature coefficient of the material (
α
) multiplied by the variation of temperature
(
∆Τ
).
Expressed in terms of the resistance:
(
)
0
0
0
T
T
R
R
R
−
=
−
α
or
(
)
[
]
0
0
1
T
T
R
R
−
+
=
α
To better understand our uses of the equation, we will now express it in terms of our
application.
(
)
[
]
R
A
C
M
T
T
R
R
−
+
=
α
1
Where R
C
is the compensated value, R
M
is the measured resistance, T
A
is the ambient
temperature and T
R
is the temperature reference. The compensated resistance is therefore
calculated as follows:
(
)
R
A
M
C
T
T
R
R
−
+
=
α
1
The user can select from a list of temperature coefficients and temperature references.
The list is based on the most commonly used values. The user can also customize these
settings with unique values.
Once the temperature coefficient and the temperature reference are set, the instruments
task is to measure the load resistance and the ambient temperature. After all the variables
are determined, the 4176 automatically calculates the compensated resister value.
