Thytronic Pro-N NVA100X-D

FUNCTION CHARACTERISTICS
233
NVA100X-D - Manual - 02 - 2016
M(w) is a compensating factor in the current amplitude of the w side; it expresses the values that are
multiplied by the currents of the w side in order to obtain an amplitude equal to that of the currents
on one side chosen as a reference.
If inside the Set \ Base menu the MatchType=ESTERNAL parameter is set (external compensation
with adapter CTs), then:
M(w) = 1
However, if inside the Set \ Base menu the MatchType=INTERNAL parameter is set then M(w) is
calculated by the relay as follows:
Calculation of the rated currents of the sides of the transformer from S
nt
rating (in MVA) and rated
voltages V
ntH
, V
ntL
in kV programmed in the Set \ Transformer menu:
I
ntH
= 1000 ∙ S
nt
/ [√3 ∙ V
ntH
] rated current of side H of transformer
I
ntL
= 1000 ∙ S
nt
/ [√3 ∙ V
ntL
] rated current of side L of transformer
Calculation of the difference (mismatching) between the CT primary rated current and rated cur-
rent of the sides of the transformer, starting from the I
npH
, I
npL
, I
nH
, I
nL
programming parameters
inside the Set \ Base menu and from the currents calculated in the preceding paragraph:
m
H
= I
npH
/I
ntH
mismatching coeffi cient on side H of transformer
m
L
= I
npL
/I
ntL
mismatching coeffi cient on side L of transformer
where: I
npH
, I
npL
are the CTs rated current on sides H and L
The relay checks that the values of the mismatching coeffi cients are between 1.0 and 2.5, if the
condition is not met, a warning message is issued and a correction of the S
nt
, V
ntH
, V
ntL
, I
npH
, I
npL
parameters is required.
Choosing the transformer side
[1]
(RefSide) that the current amplitude compensations are taken
as a reference: the side reference chosen by the relay is the one with the lowest mismatching
coeffi cient. If the two sides have an equal value of the mismatching coeffi cient, the reference is
chosen as the side with the index H
If H is the reference side for current amplitude compensation, the current amplitude factors M (w)
are calculated as follows:
M
(H)
= [m
H
/ m
H]
] / [I
nH
/I
nH
] = 1
M
(L)
= [m
L
/ m
H]
] / [I
nL
/I
nH
]
If L is the reference side for current amplitude compensation, the current amplitude factors M (w)
are calculated as follows:
M
(H)
= [m
H
/ m
L]
] / [I
nH
/I
nL
]
M
(L)
= [m
L
/ m
L]
] / [I
nL
/I
nL
] = 1
Polarity matching
P (w) is the matrix of the amperometric polarity of w side. It allows us to consider each with its own
input current phase angle (coeffi cient +1 with NORMAL setting) or with opposite phase angle (with
coeffi cient -1 REVERSE setting), allowing correction of any sw current polarity reversals due to
connection errors.
P(w) is defi ned as:
The coeffi cients of amperometric polarity (C1-C2 POL for p
L1(H)
, C3-C4 POL for p
L2(H)
, C5-C6
POL for p
L3(H)
, A1-A2 POL for p
L1(L)
, A3-A4 POL for p
L2(L)
, A5-A6 POL for p
L3(L)
) can each take
the value +1 (NORMAL) or -1 (REVERSE), based on the programming of the same coeffi cients in the
Set \ Polarity menu. If the amperometric polarity correspond to those of the corresponding wiring
diagram programming is +1, otherwise -1.
Phase, ciclic sequenze and zero sequenze matching
C (w) is the matrix of phase compensation and cyclic sequence and zero-sequence currents of the
Note 1 settings of the differential protection are referred to the CT’s rated current on the side chosen by the relay as a reference for amplitude compen-
sation in (Inref).
The side chosen as a reference for amplitude compensation (RefSide) and the primary CT rated current of that side (Inref) are displayed in the
Set \ Base menu
A)
B)
C)
D)
P
(H)
= 0 p
L2(H)
0
p
L1(H)
0 0
0 0 p
L3(H)
P
(L)
= 0 p
L2(L)
0
p
L1(L)
0 0
0 0 p
L3(L)