User Manual

86
Peak factor of current of phase (i+1) with i ∈ [0; 3] (i = 3 ⇔ neutral).
[ ]
[ ] [ ]
[ ][ ]
∑
−
=
⋅
=
1
0
2
1
)iApm,iAppmax(
Acf
NechSec
n
niA
NechSec
i
Note: NechSec is the number of samples in the second. The duration of evaluation of the peak values here is one second.
16.1.2.7. Rms values (neutral included except Vrms and Urms – over one second)
RMS phase-to-neutral voltage of phase (i+1) with i ∈ [0; 2].
[ ] [ ][ ]
∑
−
=
⋅=
1
0
2
1
Vrms
NechSec
n
niV
NechSec
i
RMS phase-to-phase voltage of phase (i+1) with i ∈ [0 ; 2].
[ ] [ ][ ]
∑
−
=
⋅=
1
0
2
1
Urms
NechSec
n
niU
NechSec
i
RMS current of phase (i+1) with i ∈ [0; 3] (i = 3 ⇔ neutral).
[ ] [ ][ ]
∑
−
=
⋅=
1
0
2
1
Arms
NechSec
n
niA
NechSec
i
Note: NechSec is the number of samples in the second.
16.1.2.8. Negative-sequence unbalance rates (three-phase connection – over one second)
These are calculated from the filtered RMS vector values (over one second) VFrms[i] and AFrms[i] for distribution systems with
neutral and UFrms[i] and AFrms[i] for distribution systems without neutral. (Ideally the fundamental vectors of the signals). The
formulas used make use of Fortescue’s symmetrical components from Fortescue’s negative-sequence transformation.
Note: The operations are vector operations in complex notation with
3
2
j
e=a
π
Positive-sequence fundamental symmetrical phase-to-ground voltage (vector) in a distribution system with neutral
[ ] [ ] [ ]
)2VFrmsa1VFrmsa0VFrms(
3
1
Vrms
2
⋅+⋅+=
+
Negative-sequence fundamental symmetrical phase-to-ground voltage (vector) in a distribution system with neutral
[ ] [ ] [ ]
)2VFrmsa1VFrmsa0VFrms(
3
1
Vrms
2
⋅+⋅+=
−
Negative-sequence unbalance factor of the phase-to-ground voltages in a distribution system with neutral
+
−
Vrms
Vrms
=Vunb
Remark: The following quantities are saved with the negative-sequence unbalance factor in a trend recording: Vns = |Vrms-| and
Vps = |Vrms+| (the norms of the negative-sequence and positive-sequence fundamental symmetrical components,
respectively).
Positive-sequence phase-to-phase fundamental symmetrical voltage (vector) in a distribution system without neutral
[ ] [ ] [ ]
)2UFrmsa1UFrmsa0UFrms(
3
1
Urms
2
⋅+⋅+=
+
Negative-sequence phase-to-phase fundamental symmetrical voltage (vector) in a distribution system without neutral
[ ] [ ] [ ]
)2UFrmsa1UFrmsa0UFrms(
3
1
Urms
2
⋅+⋅+=
−