Large power transformers operate at very low power
factor (<0.01) and the phase accuracy is critical to
measure the losses. Power transformer application
mode sets the configuration options to the optimum
for phase accuracy e.g. AC+DC coupling range lock
across phases. The temperature can be monitored at
the same time by connecting a suitable temperature
sensor to the “torque” BNC input
Temperature mode can be disabled or selected to
measure C or F via a suitable temperature sensor
connected to the “Torque” BNC input
In order to minimise standby power, some devices
operate in a “dormant” mode whereby power is only
drawn from the supply when needed. These devices
draw very little current for most of the time and then
draw a larger current for a single cycle to charge a
reservoir capacitor. This pattern is repeated on an
irregular basis. Most of the power consumed by
devices in this mode is taken in the periodic higher
current cycles so to accurately measure the power
drawn by these devices, the instrument synchronises
to the power frequency for the analysis but extends
the measurement window to the irregular period of
higher energy pulses. Because the instrument
samples in true real time without any gaps, no data is
missed and every power cycle is captured. It is
important that ranging is set to manual or up only
autoranging so that the power cycles are not missed
while ranging
Frequency synchronisation for calibration gives more
accuracy at low levels, applies to AC only
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