Chauvin Arnoux C.A 6545 Notice De Fonctionnement page 56

For example:
1 min. after the measurement stops, the DD symbol becomes steady, the display automatically
shows the value of DD if the calculation was possible.
Therefore: if the measurement lasts 1 minutes
if the measurement lasts 10 minutes
and 1 minute after the end of the measurement
Note: If, during the measurement of DAR, PI, or DD, whether automatic or not, there is a strong
external disturbance, or if the insulation resistance exceeds the device's measuring ranges, the
measurement of DAR or PI is aborted and the following is shown on the display:
In such case the measurement provides no result for DAR or PI.
A capacitance parallel to the insulation resistance extends the settling times of the measurements.
This can affect or even inhibit the measurement of DAR or PI (depending on the time set in SET-UP
for recording the fi rst resistance value). The following table shows typical values for the capacitance
parallel to the insulation resistance, at which a successful DAR or PI measurement is still possible.
The display of the DD value is:
unknown (- - - -) if C < 1 nF or Idd < 100 pA

known and fl ashing if 1 nF   C < 10 nF and 100 pA   Idd < 1 nA

known and steady if C   10 nF and Idd   1 nA

(with C = measured capacitance and Idd = current measured after 1 minute)
 Secondary function R(t)
The R(t) key is used to access the intermediate insulation resistance values measured as a function of
time, after a measurement in "Programmed-time test" mode
The time between each stored samples is programmed in the SET-UP confi guration menu.
This function is also available on model C.A 6545 that has no RAM for the storage of measured data, or
interface to recover this data from the instrument on a PC.
After pressing the R(t) key, the instrument switches to display mode:
the small display indicates a time of 00:30 (if the sampling frequency is 30 s)

the main display indicates the corresponding value R.

The V-TIME key is used to alternate between time and voltage (on the small display), with the value R
on the main display.
The key is used to scroll through all the samples stored during the measurement. This makes it
possible to note the elements for an R(t) and U(t) diagram.
It is therefore possible to perform, on-site, an R(t) analysis with no printer or PC.
A new press of the R(t) key, will exit the function.
DD - - - -
or
DAR ou
56
  DAR
  PI
  DD
PI
(see § 4.2).