Schweitzer Engineering Laboratories SEL-387E, Instruction Manual

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Date Code 20020129 Metering and Monitoring 5-7
SEL-387E Instruction Manual
Harmonic Metering Function (METER H Command)
The harmonic metering function, in response to the METER H ( MET H ) command, retrieves
one full cycle of unfiltered sample data (64 samples) from each of the 12 analog inputs.
Harmonic magnitudes are obtained using a Fast Fourier Transform method, which calculates a
discrete Fourier transform, given by the following equation, for each harmonic from fundamental
to 15th.
N
kn 2
• j
1 N
0 k
k n
e • h H
p
-
=
Ê
=
Where,
N = samples per cycle = 64
n = order of the harmonic = 1, 2, …, 15
h
k
= sampled data for one full cycle at system frequency
k = summation index = 0, 1, …, 63
H
n
= result of the discrete Fourier transform calculation for the nth harmonic
After all harmonics are calculated, they are adjusted to compensate for filter gain, and the
resulting magnitudes are listed in secondary quantities:
=>>METER H<ENTER>
processing harmonic spectrum ............
XFMR 1 Date: MM/DD/YY Time: HH:MM:SS.SSS
STATION A
Magnitudes of Harmonic Currents (Amps Sec, Volts Sec)
H IAW1 IBW1 ICW1 IAW2 IBW2 ICW2 IAW3 IBW3 ICW3 VAWX VBWX VCWX
1 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
2 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
3 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
4 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
5 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
6 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
7 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
8 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
9 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
10 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
11 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
13 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
14 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
15 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12 123.12
=>>
The Analog Input Labels, IAW1, etc., will be listed as they are set in the Global Settings section
of the relay.