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MDA-550/MDA-510
Users Manual
14
Motor Drive Input
The Motor Drive Input functions check the drive input
conditions. Input voltage relates to the quality of the mains
power that feeds the drive. Input current depends on the
loading of the drive and the condition of the drive input
section.
Voltage and Current
Voltage and Current measurements check for supply
voltage, current, and frequency at the Motor Drive input.
The measurement is done on one of the phases and for
3-phase systems can be repeated for the other phases.
Voltage measurements between two phases (Phase-
Phase) or between phase and ground (Phase-Ground) is
selected in the submenu.
The display shows the voltage waveform in red and the
current waveform in blue. The rms voltage, rms current and
frequency are displayed as readings in the top of the
display.
For displayed readings, use
to change to the Volt
Peak readings or Current Peak readings: Peak-Peak,
Maximum Peak, Minimum Peak as well as the Crest Factor
(ratio between peak and rms value). This only changes the
readings. The voltage and current waveform continue to
show on the display with no change.
Tips:
•
The test tool can compare the rms voltage against the
intended nominal voltage. The Vrms should be ±10 % of
the intended voltage.
•
If the voltage is low:
•
Check if the local circuit is overloaded.
•
Check if the load of the circuit matches the current
rating of the circuit breaker. A high current load can
result in a low voltage on the drive input.
•
Check the sizing of the conductor feeding the
circuit to see whether the cable size is within
specifications compared to local requirements.
•
If the voltage is ±10 % of intended voltage, the
voltage level is not the problem during the
measurement period. Certain conditions can cause
the voltage to go outside of the acceptable limits
during other time periods.
•
When the Motor Drive is on, the waveform does
not have a typical sinewave, for example, it can
look more like a camel hump shape. The current
readings and waveform shape can vary as the load
changes.
•
Compare the measured frequency against the
specified frequency intended for that circuit.
Nominal frequency (typical 50 Hz or 60 Hz) should
be within 0.5 Hz of specification.
•
When using a MDA-550, select Harmonics to
determine the harmonics related to the waveform
shape for both voltage and current (see Harmonics
section).