HT7
EN - 8
4.6. AC VOLTAGE MEASUREMENT WITH LOW INPUT IMPEDANCE
CAUTION
The maximum input for AC voltage is 690V. Do not measure higher
voltages to avoid risks of electrical shocks or serious damages to the
instrument.
symbol is lighted up whenever the voltage between the probes
exceeds 50V, even if the batteries are low or have been removed.
This function is particularly useful for testing installations. Thanks to the low input
impedance, voltage due to stray capacitance coupling is nulled. The reading shows the
voltage applied. Similarly, measuring line to earth voltage (V
L-PE
) may trigger residual
current circuit breakers (RCD). This measuring procedure can be used for
measurements above 12V.
Fig. 4: AC voltage measurement with
low impedance
1. Perform the preliminary Autotest (see § 4.3)
2. Connect the L1 and L2 probes to the object
under test (see Fig. 3). The measurement is
performed only when probes are in contact
to live conductors.
3. The instrument turns automatically on and the
measured AC voltage value is displayed both
in numerical and bargraph modes. AC symbol
is displayed. Always keep the instrument in
vertical position for an optimal display
reading.
4. The symbol is lighted up for AC voltage
measurements from 100V to 690V, 50/60Hz.
5. Press the two switches (see Fig. 1 part 8
and 11) simultaneously. The applied
voltage is displayed on the LCD.
6. The low impedance LED indicates the low
input impedance voltage measurement
(load connection).
7. Press the key to switch on the white LED
illuminator to perform measurements in dark
environments.
CAUTION
The maximum allowed use of low input impedance measurement is 5
seconds for voltages up to 250V and 3 seconds for voltages up to 690V.
Afterwards, please wait 10 minutes before taking further measurements.
The single-wire test is not suitable to measure voltage. For this purpose,
the two-wire voltage testing is necessary.
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