Measurement Computing WavePort 312P rev.1.0 - Manual (Page 68)

8-4 Cycle-by-Cycle Capture PowerVista/312 User’s Manual
For arc furnace applications, poor SVC response can manifest itself through increased flicker, longer melt times,
lower quality melts, and overall higher cost of energy per melt.
8.3.4 Flicker
Flicker is in essence Cycle-by-Cycle captured voltage data post processed to determine magnitude and
frequency components of voltage excursion. This analysis is not presently available in Version 1.0 of
EasyPower Measure but will be included in Version 2.0 as a separate acquisition feature.
Nonetheless, Cycle-by-Cycle data can still be used for flicker analysis in any post processing tool that
accommodates delimited data from the Window's Clipboard (using Copy Delimited). The most common
analysis that can be performed is a distribution or pdf (probability density function) where (like a Gaussian bell
curve) voltages are grouped into bins of a given voltage excursion.
In addition, post processing tools that contain Fourier frequency analysis or an FFT function, will allow voltage
variations with associated frequency of occurrence to be determined. Note that this method assumes that
variations in voltage at a given frequency are by definition sinusoidal variations. Thus it is not a valid
comparison to plot such answers on a flicker curve where thresholds of sensitivity are determined by square
wave or on-off like voltage variations.
8.3.5 Exciter, Generator and Governor Response Tests
Step response tests of rotating electrical equipment can also be performed using EasyPower Measure. Since
two additional inputs are supplied, most additional data for a performance test can be accommodated. As noted
in Power Grid Dynamic Response, post processing of data will be essential for these tests as well. All digitized
information is readily accessible via the Windows Standard Copy Delimited Data to Clipboard feature.
Several possible tests are listed below with input options.
• Generator V Curves
⇒ Terminal Voltage: Three phase voltage inputs.
⇒ Power: Supplied three phase power calculation.
⇒ I Field: Channel E1 - and Hall Effect current transducer.
⇒ V Field: Channel V4 - direct input.
• Exciter Step Test
⇒ Terminal Voltage: Three phase voltage inputs.
⇒ V Ref: Channel E1 - direct low voltage input.
⇒ V Field: Channel V4 - direct input.
• Governor Step Test
⇒ Machine Speed: From monitored voltage frequency.
⇒ Machine Power: Supplied three phase power calculation.
⇒ Governor Position: Channel E1 - low voltage input from external position sensor.
⇒ Speed Ref: Channel V4 - direct input.