ABB Relion 670 Series Applications Manual page 277

1MRK 511 401-UEN Rev. K
L3
L2
L1
Su =2
IEC19000931 V1 EN-US
Figure 131: Units arrangement in an ungrounded single WYE connected capacitor bank
The per unit capacitance of the internal group based on the number of blown fuses is
calculated as,
-
P
=
e
C
i
P
IECEQUATION19344 V1 EN-US
Where,
P is the number of parallel elements in a unit = 9.
e
f is the number of fuses that are blown in one parallel group of elements inside one capacitor
unit.
The per unit capacitance of the affected capacitor unit is calculated as,
=
C
u
C
i
IECEQUATION19345 V1 EN-US
Where,
S is number of series elements in a unit = 9.
e
The per unit capacitance of the parallel group of capacitors that include blown fuses is
calculated as,
(
P
=
C
g
IECEQUATION19346 V1 EN-US
Where,
Bay control REC670
Application manual
Pu = 3
f
e
´
S C
e i
( )
´ - +
S 1 1
e
)
- +
1 C
a u
P
a
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Single Capacitor Unit
Ce
Cu
Pu = 9
Section 10
Unbalance protection
Se =4
IEC19000931-1-en.vsdx
(Equation 158)
(Equation 159)
(Equation 160)
271