12.29
Date Code 20080213
Instruction Manual
SEL-351A Relay
Standard Event Reports and SER
Example Standard 15-Cycle Event Report
Figure 12.6
Derivation of Phasor RMS Current Values From Event Report
Current Values
, note that two rows of current data from the event report in
, 1/4 cycle apart, can be used to calculate phasor rms current
, at the present sample, the phasor rms current value is:
IA = 2749 A
∠
–32.6°
The present sample (IA = 2317 A) is a real rms current value that relates to the
phasor rms current value:
2749 A * cos(–32.6°) = 2317 A
IA
t
IA
1474
–2320
–1479
2317
Event Report Column
X = Present Sample
Magnitude =
X = 2317
Y = –1479
Angle =
Arctan
= Arctan
Y
X
–1479
2317
=–30.0˚
Real Axis
Axis
Imaginary
1/4 cyc.
(–1479)
2
+ (2317)
2
= 2749
Y = Previous
1/4 Cycle
Summary of Contents for SEL-351A
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