B
Appendix
EPQ DataNode Series User’s Guide
B-5
Transients tab
Properties
Values
Limit Methods
Voltage trigger method
Manual (% of fixed base)
{Manual (Engineering units)}
{Manual (% of fixed base)}
Current trigger method
Automatic (% of base current)
{Manual (Engineering units)}
{Manual (% of base current)}
Cycle Counts
Number of pre-trigger cycles
2
Number of post-trigger cycles
2
Individual Channel Parameters
A-N Voltage
B-N Voltage
C-N Voltage
N-G Voltage
A Current
B Current
C Current
N Current
Instantaneous limit enabled
Instantaneous limit
25.0
Waveform change limit enabled
Waveform change magnitude limit
10.0
Waveform change duration limit (% of cycle)
10.0
Additional Notes on Transients
Kinds of Transient
Impulses
An impulsive transient is a short duration disturbance characterized by a very rapid change in the magnitude of the mea-
sured quantity. Lightning strokes, the most common cause of this type of disturbance, produce current impulses typical-
ly lasting from 30 - 200 microsec, with 1 - 10 microsec rise times (Figure B.2 next page). Due to the high frequencies
involved (5 kHz or greater), these types of transients are damped quickly by the resistive components of the system.
Thus, they tend to be unidirectional, at least close to the source of the transient.
The voltage transient that results from a lightning-induced current impulse is a function of utility pole grounding and the
surge or high frequency impedance of the line. The magnitude of the voltage impulse is limited by arrester operation or
insulation flashover. Oscillations are produced when the resulting traveling wave is reflected at line ends and other circuit
discontinuities.
