Operation Manual

46 GMC-I Messtechnik GmbH
4.6 Voltage Measurement (protection against residual voltage)
EN 60204 requires that voltages in excess of 60 V occurring at all
accessible machine components during operation must drop to a
residual voltage value of 60 V or less within a period of 5 seconds
after supply power has been switched off.
Testing for the absence of voltage is performed by means of a
voltage measurement which involves measuring discharge time
with the MERISO PRIME+. Elapsed time as of disconnection
from supply power is displayed continuously at the LCD during
discharge, until the limit value of 60 is reached.
In addition to voltage type (AC, DC or AC+DC), frequency is mea-
sured and displayed as well. The mean value is always read out.
In addition to voltage and frequency, voltage type (AC, DC or
AC+DC) appears at the symbol field in the display.
If voltage drops by more than 5% of the measured value during a
single measuring period (approx. 0.7 sec.) while performing a volt-
age measurement which results in a value of greater than 60 V, a
time measurement is started automatically in order to test protec-
tion against residual voltage. This time measurement can be
observed at the display in the symbol field. Time measurement is
stopped after voltage drops to below the limit value of 60 V. Time
required to discharge down to 60 V then appears at the display in
seconds. Voltage measurement continues until maximum allow-
able discharge time has elapsed (normally 5 seconds). The results
of the voltage measurement are then “frozen”, and the
DATA HOLD symbol appears at the display. If the 60 V limit value
is not reached before allowable discharge time has elapsed, the
voltage value is “frozen” and time measurement continues until
the 10 second time limit has elapsed. If voltage is still greater than
60 V after 10 seconds, the test is aborted and the instrument
restarts voltage measurement.
When the display is “frozen”, voltage measurement is not started
again until:
• The START key is pressed.
• The measured value is saved to memory by pressing the
i/Store key.
• Voltage measurement is restarted from the menu.
• Or voltage at the test probes climbs back up to a value of
greater than 60 V, or if the next measured value after a mea-
surement of greater than 60 V is even higher, i.e. if a climbing
tendency can be observed.
Both elapsed time and the prevailing voltage value after allowable
discharge time has elapsed are saved to memory by pressing the
i/Store key. If no discharge takes place, only the voltage value is
saved.
Note
If, for example, conductors are exposed when a machine
is switched off – e.g. if plug connectors are disengaged –
and if these are not protected against direct contact,
maximum allowable discharge time is 1 second!
TEST
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