Ambient temperature compensation
C.2.4
a) Principle
The metals used in the windings of certain components (for example, the copper wire used in transformer or
motor windings) have high temperature coefficients of the order of 0.4%/°C (for copper or aluminium). This
leads to resistance level measurements that are highly dependent on the temperature of the component.
The "Temperature Compensation" function can be accessed by pressing the key. It is used to return
the resistance value, which is dependent on the ambient temperature (whether measured or programmed), to
the value that it should have at a reference temperature level:
The compensated resistance level is expressed as follows:
R(Tref)= R(Tamb) * (1 + alpha* Tref )
1 + alpha*Tamb
R(Tamb) the resistance value measured at ambient temperature
Tamb the temperature level measured by a Pt100 probe or programmed by the user
alpha the temperature coefficient of the chosen metal (Aluminium, Copper, "Other metal")
Tref the programmed reference temperature to which the measurement level is returned
These parameters are programmable ones (refer to sub-section 3.4).
b) Using the Compensation Function
Check parameter programming (see sub-section 3.4.8) and the connections made.
Press this key; the unit displays the following information on-screen:
R (θ), the chosen metal and the temperature levels Tref then Tamb.
Select the range and the measurement mode, and press the key.
The unit performs a measurement cycle and directly displays the compensated resistance value and,
depending on how it is programmed, displays one of the following:
1. The programmed ambient temperature level.
2. The temperature level measured by the temperature sensor.
3. "- - - -" if the temperature sensor is validated but:
is incorrectly or not connected at all.
the measured temperature level is out of range (from –10°C to 55°C).
If a temperature level is out of range or if the sensor wires become disconnected, the unit displays Err 10.
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