9.14
SEL-700G Relay
Instruction Manual
Date Code 20170814
Analyzing Events
Event Reporting
waveform and rms values. Figure 9.5 shows how the event report current
column data can be converted to phasor rms values. Voltages are processed
similarly.
In Figure 9.4, note that you can use any two rows of current data from the
analog event report, 1/4 cycle apart, to calculate rms current values.
Figure 9.4
Derivation of Analog Event Report Current Values and RMS
Current Values From Sampled Current Waveform
In Figure 9.5, note that you can use two rows of current data from the analog
event report, 1/4 cycle apart, to calculate phasor rms current values. In
Figure 9.5, at the present sample, the phasor rms current value is:
Equation 9.1
The present sample (IA = 940.7 A) is a real rms current value that relates to
the phasor rms current value:
Equation 9.2
(752.0)
2
+ (–941.0)
2
= 1204
(–750.3)
2
+ (940.7)
2
= 1204
(–941.0)
2
+ (–750.3)
2
= 1204
Event Report Column
752.0
–941.0
–750.3
940.7
IA
1
2
2
2
Multiply by
1
Multiply by
940.7
–941.0
–750.3
752.0
–1061.1
–1330.8
1063.5
1330.4
t
IA (peak)
1/4 cyc.
IA
peak
= 1703A
peak
1703 A
peak
= 1204 A
RMS
•
•
•
752.0
—941.0
—750.3
940.7
•
•
•
IA
1204 A
38.6
–
=
1204 A
cos
38.6
–
•
940.7 A
=
Summary of Contents for SEL-700G Series
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