GE BUS1000 Instructions Manual page 17

3.3. SENSITIVITY EQUATION OF THE PERCENT RESTRAINT UNIT
From fig. 4 we may draw out the following equations.
= −
I I I
D FAULT X
=
I * R I * R
D E X MAX
From (1) and (2) we have:
= +
I I I ( * R
FAULT D D E
= +
I * 1 ( ( R / R
D E MAX
= +
I I * 1 ( 2 ( * R
F D E
= + =
I I I I
F FAULT X D
We find that the unit will produce an output (operate) when:
− ≥
I K * I 0 1 .
D F
So:
≥ +
I K * I * 1 ( 2 ( *
D D
− +
I * 1 ( K * 1 ( 2 ( *
D
In the same way the unit does not operate when:
− +
I * 1 ( K * 1 ( 2 ( *
D
For more security we can say that the unit will not trip if:
− +
I * 1 ( K * 1 ( 2 ( *
D
OR
− +
1 K * 1 ( 2 ( * R / R
E
Thus:
< +
1 K * 1 ( 2 ( * R / R
E
< +
R K * R 2
MAX MAX
From this we can finally deduce that:
> * −
R R 1 ( K ) 2 /
E MAX
2 * K * R
<
E
R
−
MAX
1 K
GEK-98514B
=
/ R )
MAX
))
/ R ))
MAX
+ +
* 1 ( ( R / R ))
E MAX
R / R ))
E MAX
≥
R / R ))) 0 1 .
E MAX
<
R / R ))) 0 1 .
E MAX
<
R / R ))) 0
E MAX
<
)) 0
MAX
))
MAX
* K * R
E
K
BUS1000 Busbar Protection
I ( * R / R )
D E MAX
3. OPERATION PRINCIPLES
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