User Manual
Application examples
Measurement solutions
There are two ma
in wiring configuration that can be used while measuring
three phase power. The two w attmeter method is common with 3-phase, 3-wire
applications and three wattmeter method is common with 3-phase, 4-wire
applications. Refer to the w iring section for details on all available wiring
configurations. (See page 47, Wiring.)
The two wattmeter method can be used for measuring efficiency on three phase in
and three phase out applications using four p ower measuring channels. The three
wattmeter method is preferred for applications that have a dedicated neutral cable.
The follow
ing methods discuss different configurations for three phase power
measurement and demonstrates efficiency measurements on a three phase system.
Method 1: Efficiency
measurem
ents on three
phase PWM motor drive
(PA3000 direct)
This method demonstrates three phase power and efficiency measurements on
asingle
phase input and three phase output PWM motor drive directly on the
PA3000 display.
Test Setup
The foll
owing steps describe the process to set up the efficiency measurement on
a single phase input PWM motor drive using the PA3000.
1. Connec
t the single phase AC input on the PWM motor drive to the first
channel of the PA3000 using a Tektronix Breakout Box (BB1000) as shown
in wiring diagram.
The breakout box taps into the current signal and measures the voltage across
the input terminals. It makes it e asier and safer to connect input AC signal on
the DUT with the 4 mm safety leads provided with the PA3000.
2. Connect the three phase output of the PWM drive to other three channels
using the 3 phase 4 Wire configuration as shown in the wiring diagram.
All three phases are set up in series with the internal shunt and the voltage is
measured across respective phase and neutral.
3. If the motor drive does not have a dedicated neutral cable, create a floating
neutral by connecting all three VLO terminals on channels 2, 3, and 4 together.
PA3000 Power Analyzer User Manual 113