Measurement In Non-Inductive Resistance Mode With Automatic Triggering; Temperature Compensation : R(Θ) Key; Principle - Chauvin Arnoux C.A 6250 Manual De Instrucciones

Remarks :
If the range is exceeded, the instrument displays Err 07.
I
This mode has many advantages :
I
- it reduces the consumption, because the current is cut off between measurements, and so
increases the battery life,
- it avoids a temperature rise in the resistance measured,
- It improves the compensation of spurious electromotive forces (because they are measured
and compensated before each resistance measurement).

3.2.3 Measurement in non-inductive resistance mode with automatic triggering

This mode is intended only for measuring resistances without time constants.
In this measurement mode, there is no need to press START (other than to start the whole
measurement process)
The measurement is triggered automatically as soon as the current and voltage circuits are
established (as soon as contact is established) and stops automatically as soon as the
measurement result is available.
Another measurement is started automatically as soon as the current and voltage circuits are established
again (as soon as contact is established again), etc.
Description:
I
- press the START key to activate the cycle.
- connect the wires to the resistance. The instrument remains on standby until the links are established.
- measurement of
- establishment of measuring current I, measurement of the voltage U1 on the terminals of the
resistance, and display of the measurement R = (U1-U0)/I
- to make another measurement, it is necessary to release at least one link, then reestablish it.
- cycle ended by pressing the STOP key
Remark: If the range is exceeded, the instrument displays Err 07.
3.3 TEMPERATURE COMPENSATION : R (θ θ θ θ θ ) KEY

3.3.1 Principle

The metals used for the windings of certain components (e.g. the copper in transformers and motors)
have large temperature coefficients (of the order of 0.4 %/°C for copper and aluminium).
This makes resistance measurements strongly dependent on the temperature of the component.
The "temperature compensation" function is used to adjust the resistance measured, which depends
on the ambient temperature (measured or programmed), to the value it would have at a programmed
reference temperature.
The "temperature-compensated" resistance is calculated as follows:
R(t°ref)= R(t°amb) * (1 + (alpha * t°ref ) )
1 + (alpha * t°amb)
where
R(t°amb): resistance measured at ambient temperature by the instrument
t°amb: temperature measured by a Pt100 or programmed by the user
Alpha: temperature coefficient of the selected metal (Aluminium, Copper, or "Other metal")
t°ref: programmed reference temperature to which the measurement is referred
t°amb, alpha and t°ref are parameters that can be programmed in SET-UP (see § 3.6.).
or STOP to
residual voltage Uo
32
start or stop the
on the terminals of
measurement.
the resistance.