Voltage Modulation; Phase-Phase - Fluke MDA-550 User Manual

Voltage Modulation

Use voltage modulation to display the modulated output
signal.The submenu has selection for what reference is
used for the measurement.

Phase-Phase

Phase-Phase shows the modulated signal between
2 phases. The PWM voltage, voltage peak-peak, frequency,
and volt/frequency ratio show as readings in the top of the
display. PWM voltage shows on the display but not the rms
voltage. PWM voltage represents the effective voltage of
the switching output based on the average value of samples
over a whole number of periods of the fundamental
frequency.
adjusts the zoom level (1, 2, or 3) of the waveform
as well as the corresponding readings.
For Zoom 2, the test tool selects a time base that shows the
pulses in more detail and the readings change to Volt Peak
Max, Volt Peak Min, and delta voltage between the upper
and lower levels.
BURST (positive or negative) selects either the
positive part of the modulated signal or the negative part of
the modulated signal. This selection also applies when you
change to Zoom 3.
For Zoom 3, the test tool selects a time base that shows the
edge of pulse of the modulation signal. A pulse with a high
peak is selected automatically to find the highest dV/dt
value.
The readings change to Volt Peak Max, dV/dt, risetime, and
overshoot percentage when Peak is selected as Risetime
with . The risetime measurement is based on the
IEC 60034-17 method that uses the 10 % and 90 % values
of the peak of pulse. This peak value is used as dt in the
dV/dt reading and the Peak Voltage as dV. Make sure that
the slope that is automatically selected is indeed the pulse
of the PWM signal and not of an interference. The start of
the slope must be around the 0-level.
LEVEL selects the readings for Delta Voltage,
dV/dt, risetime, and overshoot percentage. The risetime
measurement is based on the NEMA MG1 Part 30.1
method that uses the 10 % and 90 % values of the voltage
level. This value is used as dt in the dV/dt reading and the
level voltage as dV.
To change the view of the waveform manually in any of the
Zoom modes:
mV
1. Push or
MOVE
RANGE
V
2. To change the time base, use the
3. Use the voltage, time, and dV/dt reading to see if the
steepness of the switching impulses is within the motor
insulation specification.
Tips:
• High voltage peaks can damage the motor insulation
and drive output circuit and cause the drive to trip.
Overshoot higher than 50 % of nominal voltage can be
problematic.
Motor Drive Analyzer
Motor Drive Output
.
key.
s TIME ns
19