Megger MPQSIM, Руководство пользователя

Страница: 45 / 72

ADDENDUM B - SAMPLE DEMAND TRAINING
AVTMMPQSIM Rev 1 May 2017
39
Different phase rotations can be used however the 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.
Swap Phase B and C voltage inputs back to normal.
5. Phase Angles and Power Factor
a. View the Phase A Voltage and Current Waveforms on the Scope screen of the
MPQ Analyzer.
b. Change the Phase A Current phase angle on the PQ Simulator to -30°.
This simulates an inductive load, such as a motor.
The current now lags the voltage. This is because the coil is resistant to the change in ac current, per
Lenz law.
Lenz's law states that when an electromagnetic field (EMF) is generated by a change in
magnetic flux. The polarity of the induced EMF is such, that it produces a current
that's magnetic field opposes the change which produces it.
c.
View the Vectors and Power Factor on the DVM Power screen of the MPQ
Analyzer. The phase rotation due to the lagging current moves the current vector
clockwise.
NOTE: The DPF is now less than 1.0 and is positive. A positive DPF is a
sign of a lagging current (Inductive load).
d. Change the Phase A Current phase angle on the PQ Simulator to +11°. This
simulates a capacitive load such as a cap bank .
e. View the Waveforms on the Scope screen of the MPQ Analyzer. The current
now leads the voltage. This is because the capacitors will charge and discharge as
the voltage changes. This creates a phase shift.
f. View the Vectors and Power Factor on the DVM Power screen of the MPQ
Analyzer. The phase rotation due to the leading current moves the current vector
counter-clockwise.
NOTE: The DPF is now less than 1.0 and is negative. A negative DPF is a
sign of a leading current (Capacitive load).
g. Set the Current phase angles on the PQ Simulator back to nominal.