ABB 615 Series - Page 697

f
T
slip
i
oi
=
−
⋅ ⋅
δ δ
π
0
2
GUID-F94B7BCA-473F-42E1-95D5-EF5DF2DCC7C6 V1 EN (Equation 129)
f
slip
Slip frequency
T
oi
The time for the impedance to pass from the outer to the inner blinder.
δ
0
Swing angle at the outer blinder
δ
I
Swing angle at the inner blinder
The swing angles, δ
0
and δ
I
, are estimated from the measured impedance when crossing
the blinders. It is the difference in these quantities that is important for determining the slip
frequency.
If the “Adaptive” option is selected, after detecting an OSB condition, the function further
examines the slip frequency f
slip
, V dip time setting, and swing angle at the outer blinder
(δ
0
) to determine if the trip is asserted on the way in or on the way out. TRIP is activated
on the way in, entering the mho circle from an inner blinder, if the relationship in Equation
130 is true.
f
VoltagedipTm
slip
≤
−
⋅
( ) π δ
π
0
GUID-4FEE5C5D-B60F-42E5-AFED-0EBE46145537 V1 EN (Equation 130)
f
slip
Slip frequency
δ
0
Swing angle at the outer blinder
VoltagedipTm Set V dip time
Otherwise, TRIP is activated on the way out, when the impedance exits an outer blinder
and the swing repeats for the set Max number slips count in the respective enabled zone
that the swing has passed through.
If the Swing time has elapsed but the impedance exits the inner blinder and continues
through the opposite blinders without passing through the mho circle, the SWING output
is activated. The SWING output remains activated for a time determined by the Reset time
setting unless another swing occurs before the reset time expires causing the output to
remain active for another Reset time interval. If this swing is repeated for the set Max Num
slips Zn3 count and the Zone 3 enable setting is “Yes”, the SWING_TR output is activated.
The SWING_TR output remains activated for a time determined by the Trip dropout time
setting.
1MAC059074-MB A Section 4
Protection functions
615 series ANSI 691
Technical Manual