Measurement In Voltage Step Mode - Chauvin Arnoux C.A 6549 Manual De Instrucciones

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Pressing START/STOP again stops the measurement.
The last result remains displayed until the next measurement is made or the switch is turned.
When the insulation measurements stop, the circuit tested is automatically discharged via a resistor
in the instrument.
The DISPLAY key can be used to consult all information available after the measurement.
This information depends on the measurement mode selected (cf. § 4.2).
If the measurement was in Timed Run or Timed Run + DD mode, pressing GRAPH displays the insulation
measurement versus time curve (cf. § 4.2).
Pressing T° refers the measurement result to the reference temperature defined in SET-UP (cf. § 4.3).
5.2 STEP FUNCTION MODE
Test based on the principle that an ideal insulation produces the same resistance whatever the test voltage
applied.
Any negative variation of this resistance therefore means that the insulation is defective: the resistance of
a defective insulation decreases as the test voltage increases.
This phenomenon is barely observed with "low" test voltages.
In consequence, at least 2500V must be applied.
The usual test condition is a voltage increasing in steps: 5 1-mn steps.
Assessment of the result:
- a deviation of the resistance = f(test voltage) curve that exceeds 500ppm/V generally indicates the
presence of mould or other deterioration.
- a larger deviation or a sudden drop indicates the presence of localized physical damage (arcing,
"perforation" of the insulation, etc.).
Procedure :
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In the SET-UP menu, select Set Step
Function 1, 2 or 3
Example : here, step function n°3
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Define the step function and the desired
number of measurement samples (R(t)
sample).
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