Measurement Functions; Ac/Dc Voltage; Insulation Measurements - Chauvin Arnoux C.A 6545 Bedienungsanleitung

3. MEASUREMENT FUNCTIONS

3.1. AC/DC VOLTAGE

Any rotation of the switch on an insulation position sets the unit to automatic AC / DC voltage
measurement. The voltage is measured continuously and indicated on the small display.
The start of the insulation measurements is inhibited if an excessively high external voltage is present
on the terminals, before pressing START. Also, if an excessively high parasitic voltage is detected during
these measurements, they are automatically stopped and the voltage is indicated (see § 3.2).
Switching between the AC and DC modes is done automatically, in AC mode the RMS value is indicated.

3.2. INSULATION MEASUREMENTS

When the switch is rotated to an insulation position, the main display shows "tESt" and the small display
shows the selected test voltage for a short time. If the test voltage is limited to a smaller value than
selected, because of a test voltage limit set in SET-UP (see § 4.7.6), "LIM" is shown (instead of "tESt")
together with the actual voltage value. After that the main display shows "- - - - M  " and the small
display shows the voltage present at the + and - terminals of the instrument.
If, when the START key is pressed, the external voltage present at the terminals of the unit is higher
than the value defi ned by the equation below, the insulation measurement is not triggered an audible
warning signal sounds and the main display shows the message "> diSt" for a short time, then the
instrument returns to automatic voltage measurement.
with:
Upeak: peak or DC external voltage present on unit terminals
dISt: coeffi cient defi ned in the set-up menu (adjustable to 0.03 - 0.10 - 0.20 - default value: 0.03)
Un: test voltage chosen for insulation measurement
If the external voltage at the terminals of the unit is less than the value defi ned previously, the insulation
measurement is authorised. Pressing the START key immediately triggers the measurement. The value
of the measurement is displayed on the main digital display and on the bargraph. There is a beep every
10 seconds to indicate that a measurement is in progress.
If the voltage generated might be dangerous (> 120 V), the
If, during the insulation measurements, an external voltage higher than the value defi ned by the
relation below is detected, the measurement is aborted. The
value is displayed on the small digital display.
Note: Adjustment of the dISt factor optimises the measurement settling time. If there is no parasitic
voltage present, the dISt factor may be adjusted to the smallest value (0,03) to obtain the shortest
possible settling time for the measurement.
If a signifi cant parasitic voltage is present, the dISt factor may be increased so that the measurement
is not interrupted or even made possible in the fi rst place. This means optimisation of the settling time
in the presence of the parasitic voltage.
If the measurements are unstable, it is possible to use the SMOOTH function (see § 4.5).
Upeak > 0,4 x dISt x Un
symbol fl ashes and the external voltage
U peak > (dISt + 1.1) Un
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symbol is displayed.