Megger MPQSIM, Руководство пользователя

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M
AVTMMPQSIM Rev 1 May 2017
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8. Create a Swell
a. Allow the unit to record for approximately 15 seconds (minimum).
b. Start a SWELL on one of the voltage phases by setting the voltage selector to
115%.
c. Wait about 1 second.
d. Stop the SWELL by setting the voltage selector back to 100%. Note the record
screen now will register a swell .
Facility operation scan be affected by swells. Swells can cause systems and operations
to trip off line. Swells can be caused by switching off a large load, load shedding, or
switching on a large capacitor bank. Swells can also be caused by system fault
conditions.
For example : a single line to ground (SLG) fault can cause a temporary voltage rise
(swell) on the un-faulted phases.
A swell is defined as an increase in rms voltage above 1.1 pu for durations from 0.5
cycle to 1 min.
A swell is initiated when the 1/2 cycle RMS voltage of a single phase rises above the
swell threshold. The event ends when all phases are below the swell threshold minus
any hysteresis programmed by the user.
The recommended thresholds for swell detection is 1.1pu the the RMS value
aggregated every 1/2 cycle.
For example:
A 230V system the dip (sag) limit would be 253V.
A 120V system the dip (sag) limit would be 132V.
9. Create a Transient (Low Frequency / High Frequency / EFT)
a. Allow the unit to record for approximately 15 seconds (minimum)
b. Create a transient by depressing and releasing one of the transient switched on
the PQ Simulator.
Note the record screen now will register a transient.
Transient over-voltages can result in degradation or immediate dielectric failure in all
classes of equipment. Repetitive lower magnitude application of transients decreases
equipment mean time between failures. High magnitude and fast rise time of transient
over-voltages contribute to insulation breakdown in electrical equipment. This
equipment can include rotating machinery, transformers, capacitors, cables, current
and potential transformers (CTs and PTs), as wells as switchgear. In electronic
equipment, power supply component failures can result from transients. Transients
can also cause tripping of Adjustable Speed Drives due to the dc link overvoltage
protection circuitry.