This model demonstrates a differential amplifier to attenuate
the input voltage to a level that can be handled by the measurement
instrument.
Two sinusoidal source voltages with a phase shift of 120° (e.g.,
two phases of a three-phase system) feed a load resistor. The
voltage at the load resistor has to be measured but is too high for
direct measurement.
Notes
- The output of the amplifier is inverted with respect to the
differential input, as well as attenuated by the factor
1/data.k.
- The influence of the measurement instrument's input resistance
on the measurement result is small.
- The current consumption of the amplifier inputs at the source
circuit is small (
resistor1.i and
resistor2.i).
- The common of the source and the common of the amplifier are
connected by a ground resistor. In case this resistance is low, a
small current is flowing between the amplifier's common and the
source's common (
resistorGround.i). In case this
resistance is high, the amplifier's common is floating with respect
to the source's common with a high voltage
(resistorGround.v).
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