ABB REG650 Technical Manual page 90

Section 6
Differential protection
84
These are internal compensation algorithms within the differential
function. The protected power transformer data are always entered as
they are given on the nameplate. Differential function will by it self
adapt nameplate data and select proper reference windings.
é é ù ù é é
é IDA IDA ù é I A W I A W _ _ 1 _ _ 1
IDA I A W _ _ 1
ê ê ú ú ê ê
ê ú ê
= × = ×
= ×
IDB IDB A I B W A I B W _ _ 1 _ _ 1
IDB A I B W _ _ 1
ê ê ú ú ê ê
ê ú ê
ê ê ú ú ê ê
ê ú ê
IDC IDC I C W I C W _ _ _ 1 _ 1
IDC I C W _ _ 1
ë ë û û ë ë
ë û ë
1
2
EQUATION1879 V1 EN
where:
1. is the resulting Differential Currents
2. is Differential current contribution from W1 side
3. is Differential current contribution from W2 side
é IDA ù é I A W _ _ 1 ù
ê ú ê ú
= × +
IDB A I B W _ _ 1
ê ú ê ú
ê ú ê ú
IDC I C W _ _ 1
ë û ë û
1 2
EQUATION1882-ANSI V1 EN
where:
1. is the resulting Differential Currents
2. is Differential current contribution from W1 side
3. is Differential current contribution from W2 side
4. is Differential current contribution from W3 side
and where, for equation 1 and equation 2:
ID_A is the fundamental frequency differential current in phaseA (in W1 side primary amperes)
ID_B is the fundamental frequency differential current in phase B (in W1 side primary amperes)
ID_C is the fundamental frequency differential current in phaseC (in W1 side primary amperes)
Table continues on next page
ù ù é é
ù é I A W I A W _ _ _ _
I A W _ _
Vn W Vn W Vn W _ _ _ 2 2 2
ú ú ê ê
ú ê
+ + × × × ×
+ × ×
B I B W B I B W _ _ _ _
B I B W _ _
ú ú ê ê
ú ê
Vn W Vn W _ 1 _ 1
Vn W _ 1
ú ú ê ê
ú ê
I C W I C W _ _
I C W _
û û ë ë
û ë
3
é I _ _ A W 2 ù
Vn W _ 2
ê ú
× × +
B I B W _ _ 2
ê ú
Vn W _ 1
ê ú
I C W _ _ 2
ë û
3
1MRK 502 043-UUS B
ù ù
2 2 ù
2
ú ú
ú
2 2
2
ú ú
ú
ú ú
ú
_ _ 2 2
_ 2
û û
û
é IL A W _ _ 3 ù
Vn W _ 3
ê ú
× ×
C IL B W _ _ 3
ê ú
Vn W _ 1
ê ú
IL C W _ _ 3
ë û
4
(Equation 1)
(Equation 2)
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