Condition And Warning Indicators - Megger BM25 Guia Del Usuario

OPERATION
This sequential display repeats until a key is pressed or Auto
switch-off operates.
G
Note: In this mode, break-down of the circuit and the related noise
interference may cause the instrument to terminate the operation,
possibly causing a loss of display while the circuit remains energised. In
this event, it is important that the circuit is allowed to discharge before
touching any connections. If necessary, switch the instrument off, and then
on again to reset the display.

Condition and Warning Indicators

FS2
Fuse (FS2) located in the charger recess protects the low impedance guard
circuit against the application of external voltage. Guard fuse failure will be
indicated on the display only when the guard circuit is in use. To check
whether the fuse has ruptured, connect the positive terminal to the guard
terminal and start a 500 V test. If the 'FS2' display cursor flashes, the fuse
has ruptured. If the cursor flashes when the guard lead is not connected, it
indicates failure of one of the batteries or a battery fuse (which is not
externally accessible). The instrument will operate in this condition, but
the operating time between charges will be reduced; capacitance readings
will not be displayed, and no warning will be given if the guard fuse
subsequently ruptures.
BREAKDOWN
If a breakdown occurs between the test leads, the test will terminate and
the 'BREAKDOWN' cursor will flash. Selecting 'BURN' mode disables the
'BREAKDOWN' warning indicator.
14
G
EXT VOLTS
A flashing cursor below the 'EXT VOLTS' label combined with the flashing
LED on the front of the instrument, and the flashing high voltage symbols
indicates that the voltmeter is reading a hazardous voltage which
originates from an external source. The voltmeter will show d.c. voltage of
either polarity, or a.c. voltage.
NOISE
If external interference (normally 50 Hz or 60 Hz hum current) is excessive
(>2 mA at 5 kV), testing will terminate and the flashing cursor below the
'NOISE' label will be displayed.
LAST TEST
This cursor flashes on completion of a test in conjunction with the
repetitive sequence of final readings.
Error Numbers
Internal faults and errors will cause the display to show 'E' followed by a
number. While these error numbers are designed to aid internal fault
diagnosis, they can also be triggered by extreme cases of electromagnetic
interference. Error numbers E5 and E11 indicate that a negative current
has been measured.
Calibration Errors
At switch-on, the calibration check automatically adjusts the measurement
system against an internal voltage and resistor. The calibration sequence
will not finish unless the measurement system is giving consistent results
within preset limits. If the startup screen does not progress beyond the
segment check or stops with 'CAL' displayed, calibration has failed.