Pacific UPC-12, Operation Manual

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SECTION 4 OPERATION
76
4.6.3.9 TRANSIENT WFs
Selecting TRANSIENT WFs from the General Setup 2 menu ( fn , 3 , 7 , 3 ) allows you to specify the voltage
calculation method used during transients.
TRANSIENT WAVEFORM CALCULATION SETUP:
K-FACTOR CALC FOR AUTO RMS=ENABLED
(Press +/- Key to Toggle Selection
(Press ENTER or EXECUTE to Exit
RMS= : ENABLED or DISABLED.
If
ENABLED is chosen, the amplitude of each transient segment is calculated based on the
RMS value of the waveform used in that segment. Time based transients, using the same
waveform throughout, could use this setting.
For transients involving waveform substitution, the RMS calculation may cause the peak
voltages to vary. For example, a sine wave which has been modified to create a ¼ cycle
dropout is substituted for one cycle at 120 Vrms. Since it is missing a portion of the waveform,
the RMS calculation will determine that the voltage peaks must be higher than a normal sine
wave in order to maintain the specified 120 Vrms.
If
DISABLED , the RMS calculation of substituted waveforms does not occur. The amplitude of
all waveforms used in the transient will then be based on the system gain factor for each phase,
as calculated for the Program which contains the transient. This facilitates constant-amplitude
transients, such as partial cycle dropouts or sub-cycle spike transients. To have the transient
waveforms track the amplitude of the Program steady-state values, the base waveforms used in
all segments must be consistent.
EXAMPLE: If a 10% spike transient waveform is desired, the base sinewave was copied at 90%
to allow margin for the spike (see 4.6.2.2). The TRANSIENT WFs setting should be
RMS=DISABLED and the Program must use a sinewave copied at 90% but without the spike.
The Program will calculate the system gain to create the programmed voltage using the 90%
waveform and the transient will then be executed using that gain, thereby maintaining sine wave
continuity.