Megger MPQSIM, Руководство пользователя

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M
AVTMMPQSIM Rev 1 May 2017
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3. RMS, Phases and THD
a. View the voltages and current values on the DVM screen of the MPQ Analyzer.
Verify RMS voltages and currents are correct. This should always be done prior
to performing a power quality investigation.
b. View the phase angles of the voltage and current on the DVM screen of the
MPQ Analyzer.
NOTE: Always verify the voltage phase angles are correct per the power
configuration.
Always verify the current angles are less than 90° from their respective
voltage angles.
Current phase angle can never be more than 90° away from the phase
voltage. This is a sign that something is not connected properly.
c. View the scope screen of the MPQ Analyzer.
Examinations of voltage waveforms can indicate power quality problem. These can
include harmonic distortion, notching and noise.
d. View the scope harmonics screen of the MPQ Analyzer.
Examinations of the harmonics can indicate power quality problems without the need
of doing a recording.
NOTE: Harmonics can cause various problems, including heating of
transformers, and motors, reduced efficiency in motors, neutral line
overheating, capacitor bank failures, as well as equipment failure.
Even harmonics (2, 4, 6…etc) are indications of a faulty rectifier.
Negative sequence harmonics (5, 11, 17…etc) have magnetic fields that
rotate opposite the fundamental. This creates inefficiencies in motors.
Odd Zero Sequence harmonics also known as triplens (3, 9, 15…etc)
do not cancel out. They add together. This can create high neutral
currents.