MEGABRAS MPK-253 Guia Del Usuario página 9

Some notes about accuracy
In order to obtain the specified accuracy, the operator has to adjust the test
current to a value higher than the 80% of the nominal value. If it were neces-
sary, it is possible to use a lower current, but by doing this the accuracy will be
affected.
MPK-253 has an auto-compensation system that automatically eliminates the
error produced by internal offset. Thus, it is not necessary to carry out meas-
urements by reversing the polarity in order to compute the average value. Nev-
ertheless, if the operator suspect that there is a difference of temperature be-
tween the contact points that would can generate thermoelectric voltages, it is
necessary to carry out two measurements by reversing the current cables and
so, the circulation sense of the current through the resistance under measure-
ment. The resistance value to be measured will be the average between the
values in one sense and in the contrary (direct and inverse current).
Battery condition
The charge condition of the battery can be verified before or during the resis-
tance measurement. In order to achieve that, the operator has to press the
BATTERY key while the equipment is turned on. The bar-graph shows re-
maining charge as a percentile value. If during measurement the charge of the
battery achieves a critical level, the display will show the BAT message notifying
that the charge level is low. After a few minutes the measurement will be auto-
matically interrupted in order to preserve the battery from a deep discharge that
is prejudicial for its expected useful life.
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