Gossen MetraWatt PROFITEST 204, Руководство по эксплуатации, Страница: 33 / 76

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4.4 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 conducted with the
PROFITEST 204+ by means of a voltage measurement which mea-
sures discharge time as well. During discharge, elapsed time is
continuously displayed at the LCD after supply power has been
switched off, until the limit value of 60 V has been reached.
In addition to the type of voltage (AC, DC or AC+DC), the
respective frequency is measured and displayed as well. The
mean value is always read out.
In addition to voltage and frequency, type of voltage (AC, DC or
AC+DC) is displayed in the symbol field at the bottom right-hand
portion of the display.
If, during a voltage measurement with a measured value of more
than 60 V, the voltage value drops by more than 5% of the
measured value during one measuring period (approx. 0,7 s), time
measurement for the testing of protection against residual voltage
is started automatically. Elapsed time can be observed in the
symbol field at the display. Time measurement is stopped as soon
as the measured value drops to below the 60 V threshold.
Elapsed time required for discharge to 60 V now appears at the
display. Voltage measurement continues until maximum allowable
discharge time has elapsed (normally 5 s). The measured voltage
value is then frozen and the DATA HOLD symbol appears at the
display. If the 60 V limit is not reached within the allowable
discharge period, the voltage value measured at the end of this
period is frozen and time measurement continues until 10
seconds have elapsed. If the voltage value is still above 60 V, the
test is aborted and the instrument resumes voltage measurement.
If a value has been frozen at the display, voltage measurement is
not resumed by the instrument until:
• The START key is pressed
• The measurement is stored to memory with the i/STORE key
• Voltage measurement is restarted from the menu
• Voltage at the test probes climbs again to a value of greater
than 60 V, or, assuming the last measured voltage value was
greater than 60 V, the following measured value is even higher,
i.e. if rising voltage can be observed.
Elapsed time and the measured voltage value at the end of the
allowable discharge period are stored to memory by activating the
i/STORE key. If discharge does not occur, only the voltage value is
saved.
Note
If conductors are exposed when a machine is switched
off which are not protected against direct contact (e.g. if
plug connections are interrupted), the maximum
allowable discharge period is 1 second!