RFL Electronics GARD 8000 - Figure 13-32. Pu Lse Width Fault Detector

Current Differential Relay
GARD 8000 SYS RFL Electronics
June 20, 2014 13-50 973.334.3100
Figure 13-32. Pulse Width Fault Detector
13.5.1.1.4 Slope Change Fault Detector
The slope change fault detector processes the magnitude of the current and works on both positive and
negative half-cycles. A normal sinusoidal half-cycle will have an increasing current (positive slope)
for the first ¼-cycle followed by decreasing current (a change in slope to a negative slope) in the
second ¼-cycle. Thus a single slope change is expected in a half-cycle.
The slope-change fault detector looks for two slope changes in a given half-cycle. It also requires the
current to be greater than approximately 1.5A
RMS
. If both of these conditions are met the fault detector
asserts.
Software Flag set
when (-) change
detected
The Slope Fault Detector is
enabled when a change in
direction is measured prior to a
zero crossing. Fault Detector is
enabled for 75ms
The Slope Fault Detector is enabled
when the magnitude of the line current
is greater than 1.5 Amps
Figure 13-33. Slope Change Fault Detector