Chauvin Arnoux C.A 6549 Mode D'emploi page 68

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GRAPH secondary function
After a "programmed time test" measurement (Timed Run or Timed Run + DD), pressing this key displays
the insulation resistance versus measurement time curve.
This curve is plotted from the samples noted during the measurement.
The 4,3,5 and 6keys can be used to move along the curve to know the exact values of each sample.
KEYS 3/ T°
4.3
The T° secondary function is used to refer the result of the measurement to a temperature other than
that of the measurement.
This makes it possible to observe the insulation resistance over time and judge its evolution under
comparable temperature conditions.
This is because insulation resistance varies with temperature according to a quasi-exponential law. As
part of a maintenance program covering of a population of motors, for example, it is important to perform
periodic measurements under similar temperature conditions. Otherwise, the results obtained must be
corrected to refer them to a fixed reference temperature.
This function does this.
Attention :
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T° can be activated only after a measurement has been made (whatever the mode used to make it)
and before it is stored.
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If the result of your measurement is outside of the range (the display unit displays < or > to the range
possible with the test voltage used), this function cannot be applied.
Procedure :
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You have made a measurement and not yet stored it. Check that the result is not outside of the range.
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Enter the T° mode by pressing 2nd + T°
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Enter the estimated temperature («Probe Temperature»)
at which you made the measurement (by default, the
instrument proposes the value set in SET-UP).
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Set "Resistance Correction" to On to perform the
calculation.
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The calculation is performed immediately and the result
is displayed: Rc.
This indicates what the measurement result would have been
at the reference temperature.
The Reference temperature (Rc Reference Temperature)
and the coefficient DT indicated and used for the calculation
are those defined in SET-UP.
To modify them, see § 4.5.
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Attention :
To store this calculation, press 2nd + T° again (OK is
then displayed) before storing everything.
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