Megger MPQSIM, Руководство пользователя

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M
AVTMMPQSIM Rev 1 May 2017
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5. Harmonics
a. View the Harmonics Bar Chart on the SCOPE / HARMONICS screen of the
MPQ analyzer.
b. Turn on the voltage and current harmonics on the PQ simulator. Note the
change in the harmonic bar chart as the harmonics are applied.
c. View the waveform on the SCOPE screen of the MPQ analyzer. Note the
distortion .
Immediate effects of harmonics can include the misoperation of electronic controls
or uninterruptible power supplies. Over time harmonic distortion can results in
increased heating in transformers, motors, capacitors and conductors. In addition
voltage distortion can excite resonances overloading customer power factor
correction equipment.
AC current flowing though coils create eddie currents. These eddie current create
magnetic fields in opposition of the flow of current. This causes the current to be
pushed out to the edge of the wire. This is known as "skin effect". As the skin effect
increases the usable cross sectional area of the wire decreases. This increases the
impedance of the wire which in turn increases the heat. The higher the harmonic
order the greater this effect. Eddie current losses increase with approximately the
square of the frequency.
IEC 61000-2-2 specifies harmonic distortion compatibility levels dependent on the
harmonic order. The compatibility level for the voltage THD is 8% for 95% of the
time measured over a period of a week at 10 minute intervals.
IEEE 519 recommends voltage distortion limits of 8% for the total harmonic
distortion (THD) IEEE 519 recommends individual harmonic components limits be
at 5%. The compatibility level is for 95% of the time measured over a period of a
week at 10 minute intervals.
d. Turn off the voltage and current harmonics on the PQ simulator.
6. Start a Recording
Before starting a recording it is always recommended to verify several parameters.
a.
Go to the DVM screen of the MPQ Analyzer. Verify the voltages and currents
look correct.
b. Go to the DVM / POWER screen of the MPQ Analyzer
 Verify the KW is positive. If it is not then the power flow is reversed. This
can be demonstrated by placing the SOURCE / LOAD switch on the PQ
Simulator in the SOURCE position.

Verify the voltage phases angles are correct per the programmed power
configuration. This can be demonstrated by reversing the cable connection
of one of the voltage lead cables.