User Manual

The menu system
Shunts. The pow
er analyzer has three different current inputs, or shunts. They
are:
Internal 30 A. This is the default value and is used for normal current
measurement up to 30 A
rms
(200 A
pk
). This selection u ses the b lue AHI and
the gray ALO 4 mm sockets on the rear panel.
Internal 1 A. This is used for small current measurements such as those found
in standby power applications where current is less than 1 A. This selection
uses the yellow A1A and the gray ALO 4 mm sockets on the rear panel.
External. This is used for the measurement of current where an external
transducer is used and the transducer has a volta ge output. The blue and black
2 mm sockets on each analog card are used for the external shunt inputs.
CAUTION. Passing an rms current of gre ater than 15 A when the instrument
power is off can damage the instrument. To avoid damaging the instrument, do
not apply rms currents of greater than 15 A when the instrument is off.
Frequency Source
The Frequency Source menu provides the following selections:
Source
Phase Reference
Frequency Range
Source. Many measurements (including rms volts, amps and watts) are based
on calculations are dependent on the correct fundamental frequency being
determined by the power analyzer. The PA3000 uses proprietary techniques to
determine frequencies that e liminate problems created by noise when simple
zero-crossing techniques are used. It is therefore not normally necessary to adjust
the settings from the default of voltage.
The following source selections are available:
Volts. This is the default frequency source and is suitable for most
applications.
Amps. Amps can be selected if the voltage waveform is heavily distorted,
but the c urrent is not. The waveforms at the output of a PWM motor drive
are an e xample of this.
External Frequency 1 / 2. On the rear of the power analyzer there are two
counter inputs on the Auxiliary Inputs / Outputs connector. Either of these can
be used as an external frequency source for signal s where there is too much
noise on the voltage and current waveforms. Apply a TTL compatible square
wave to the external input at the required frequency.
Phase Reference. The Phase Reference is used for harmonic analysis to create a
zero-degree reference point.
PA3000 Power Analyzer User Manual 51