Sel 551 - Figure 7.4 Derivation of Phasor RMS Current Values from Event Report Current Values

7.16
SEL-551 Relay Instruction Manual Date Code 20110408
Standard Event Reports and SER
Example Standard 15-Cycle Event Report
Figure 7.4 Derivation of Phasor RMS Current Values From Event Report
Current Values
IA
cyc
1
8
t
IA
1559
-69
-1656
-2274
-1558
70
1656
event report column
(–2274)
2
+ (70)
2
= 2275
2273
X = present sample
Y =
previous
1/4 cycle
Magnitude =
X = 70
Y = –2274
Angle = Arctan = Arctan
Y
X
(
)
–2274
70
(
)
= –88.24°
Real Axis
Axis Imaginary