Chauvin Arnoux C.A 6549 Mode D'emploi page 58

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TIMED RUN +DD :
This mode is identical to the foregoing except that 1
minute after the end of the measurement the instru-
ment calculates and displays the DD term.
The measurement duration is therefore : duration of
timed run + 1 minute.
The insulation resistance vs. time curve can be
displayed after the mesurement by pressing
GRAPH, as long as no new measurement has been
started.
§
DAR :
The measurement is started by pressing START /
STOP and stops automatically when the DAR ratio
has been calculated, i.e. after 1 minute, the time
taken to recable the second insulation rasistance
value needed for the calculation (the recableing
times can be modified in SET-UP).
§
PI :
The measurement is started by pressing START /
STOP and stops automatically when the PI ratio has
been calculated, i.e. after 10 minutes, the time taken
to recable the second insulation resistance value
needed for the calculation (the recableing times can
be modified in SET-UP).
Remark : in this mode, the DAR ratio will also be
calculated automatically if the times needed to
calculate it are less than the second time needed to
calculate the PI ratio.
Important remarks
§
What is the DD (Dielectric Discharge index)?
In the case of multilayer insulation, if one of the layers is defective but the resistance of all the others is
high, neither the quantitative insulation measurement nor the calculation of the PI and DAR quality ratios
will reveal the problem.
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