Schweitzer Engineering Laboratories SEL-751 - Figure 10.5 Derivation of Phasor RMS Current Values from Event Report Current Values

10.18
SEL-751 Relay Instruction Manual Date Code 20170927
Analyzing Events
Event Reporting
Figure 10.5 Derivation of Phasor RMS Current Values From Event Report
Current Values
Retrieving Event
Reports Via Ethernet
File Transfer
Selected event reports are available as read-only files that can be retrieved
using Ethernet File Transfer Protocol (FTP) or Manufacturing Messaging
Specification (MMS). MMS is only available in models that support
IEC 61850 and only when IEC 61850 and MMS File transfer are enabled
(E61850 := Y, EMMSFS := Y). See File Transfer Protocol (FTP) and MMS
File Transfer on page 7.13, Virtual File Interface on page 7.58, and MMS on
page F.4 for additional information.
IA (RMS)
t
IA
Event Report Column
Magnitude =
X = 940.7
Y = —750.3
Angle = Arctan
= Arctan
Y
X
—750.3
940.7
= –38.6°
Real Axis
Axis Imaginary
1/4 cyc.
(—750.3)
2
+ (940.7)
2
= 1204
Y = Previous
1/4 Cycle
•
•
•
752.0
—941.0
—750.3
940.7
•
•
•
X = Present Sample
NOTE: The arctan function of many
calculators and computing programs
does not return the correct angle for
the second and third quadrants (when X
is negative). When in doubt, graph the X
and Y quantities to confirm that the
angle that your calculator reports is
correct.