Test Mode Summary - Megger BM25 Guia Del Usuario

TEST MODE SUMMARY

Insulation Resistance Testing (R)
This mode measures insulation resistance at the selected voltage to
provide an instantaneous spot reading. Final test result is given
sequentially with the corresponding leakage current and capacitance
value.
Test Current measurement (I)
This mode measures insulation at the selected voltage to provide an
instantaneous spot reading, but displays leakage current value on the
digital display. (N.B. The analogue scale always displays resistance). Final
test result is given sequentially with the corresponding resistance and
capacitance value.
Polarization Index Testing (PI)
Polarization Index is the term applied to the Dielectric Absorption ratio,
when the insulator is subjected to an insulation resistance test, and the
resistance values are measured after time T1 (Default 1 minute) and
again after time T2 (Default 10 minutes). Polarization Index is calculated
automatically from the resistance value after time T2, divided by the
resistance value after time T1. High dielectric absorption is indicated by
high PI ratio (see 'Application of test Techniques'). Final test results
are given sequentially with the corresponding leakage current and
capacitance value. The test will run at any voltage. Custom timed 'PI'
values can be set if required (see 'Custom timed PI test' on page 12).
Dielectric Discharge Testing (DD)
This mode measures the dielectric absorption of an item under test while
ignoring the effects of parallel surface leakage paths. Default test time is 30
minutes followed by 1 minute discharge. Final test results are given
sequentially with a PI value, the final resistance value, and capacitance
value. Custom timed DD values can be set if required (see 'Custom
timed DD test').
Step Voltage Testing (SV)
This 5 minute test depends on the principle that an ideal insulator will
produce identical resistance readings at all voltages. Conversely, an
insulator which is being over stressed will show lower values at higher
voltages. Operating at either 2,5 kV or 5 kV , the voltage steps up one fifth
every minute, and successive measurements are taken. On completion,
each of the 5 separate results are sequentially displayed followed by the
capacitance value.
Fault Conditioning (Burn)
This low current feature is used to carry out continuous testing under
breakdown conditions.
General Notes:
1) A capacitance value reading is only available if the test has run for
more than one minute, and the reading was not over-range.
2) Internal discharge resistors are automatically selected :-
- At the end of a test.
- If the instrument is switched off.
- If an internal error is detected.
Any voltage remaining on the terminals at the end of a test,will be
displayed until it has decayed to less than 50 V . During a test output
terminal voltage is displayed, together with flashing high voltage symbols,
and the flashing red LED.
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