HT Instruments HT7 Bedienungsanleitung Seite 27

5.3. AC VOLTAGE MEASUREMENT WITH LOW INPUT IMPEDANCE
• 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.
• Il simbolo
di tensione tra i terminali >40VAC anche con livello di batteria basso o
con batterie rimossa
• 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
(RCD). This measuring procedure can be used for measurements
above 12V
Fig. 4: AC Voltage measurement with low input 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
5. Press the two switches (see Fig. 1 part 8 and 11) simultaneously. The applied
voltage is displayed on the LCD. The low impedance LED indicates the low input
impedance voltage measurement (load connection)
6. Press the key to switch on the white LED illuminator to perform measurements in
dark environments.
• The maximum allowed use of low input impedance measurement is 5s for
voltages up to 250V and 3s for voltages up to 690V. Afterwards, please
wait 10min before taking further measurements
• The value measured in this function is to be considered indicative
and does not comply with the uncertainty declared in the AC/DC
voltage specifications
di tensione pericolosa si accende e il buzzer suona in caso
L-PE
is lighted up for AC voltage from 100V to 690V, 50/60Hz
CAUTION
) may trigger residual current circuit breakers
CAUTION
EN - 8
HT7