Cooper Lighting Low Impedance Bus Differential Relay M-LIB3 - Manual (Page 24)

M-LIB3 Low Impedance Bus Differential Relay
24
To compensate the differential current produced by CT’s error or saturation, the actual minimum operation
level I
S
is dynamically adjusted in function of the actual through current I
R
according to the set coefficient [1R],
[2R]
•
I
R
< [1I
R
] : I
S
= I
dS
‚
[1I
R
] < I
R
< [2I
R
] : I
S
= I
dS
+ 1R(I
R
-[1I
R
])
ƒ
I
R
> [2I
R
] : I
S
= I
dS
+ 1R([2I
R
]-[1I
R
]) + 2R(I
R
-[2I
R
])
„
BIAS SATURATION : I
S
= 10 In for any I
R
[2I ]
R
∆
I
R
[I /In]
ds
∆
I
R
∆
I
ds
R=
[2R]
∆
I
ds
I /In
R
[1I ]
R
‚
ƒ
„
•
[1R]
Is/In
∆
I
ds