Breaker Failure (Ansi 50Bf) - GE T60 Instruction Manual

5 SETTINGS
EXAMPLE 5: INTERNAL LOW-CURRENT, HIGH-LOAD SINGLE-LINE-TO-GROUND FAULT WITH NO FEED FROM
THE GROUND
Given the following inputs: IA = 1.10 pu ∠0°, IB = 1.0 pu ∠–120°, IC = 1.0 pu ∠120°, and IG = 0.0 pu ∠0°
The relay calculates the following values:
I_0 = 0.033 pu ∠0°, I_2 = 0.033 pu ∠0°, and I_1 = 1.033 pu ∠0°
Igd = abs(3 × 0.0333 + 0.0) = 0.10 pu, IR0 = abs(3 × 0.033 – (0.0)) = 0.10 pu, IR2 = 3 × 0.033 = 0.10 pu,
IR1 = 1.033 / 8 = 0.1292 pu, and Igr = 0.1292 pu
Despite very low fault current level the differential current is above 75% of the restraining current.
EXAMPLE 6: INTERNAL HIGH-CURRENT SINGLE-LINE-TO-GROUND FAULT WITH NO FEED FROM THE GROUND
Given the following inputs: IA = 10 pu ∠0°, IB = 0 pu, IC = 0 pu, and IG = 0 pu
The relay calculates the following values:
I_0 = 3.3 pu ∠0°, I_2 = 3.3 pu ∠0°, and I_1 = 3.3 pu ∠0°
Igd = abs(3 × 3.3 + 0.0) = 10 pu, IR0 = abs(3 × 3.3 – (0.0)) = 10 pu, IR2 = 3 × 3.3 = 10 pu, IR1 = 3 × (3.33 – 3.33) = 0
pu, and Igr = 10 pu
The differential current is 100% of the restraining current.
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PATH: SETTINGS GROUPED ELEMENTS
 BREAKER FAILURE 1
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GE Multilin
 
SETTING GROUP 1(6) BREAKER FAILURE
BF1 FUNCTION:
Disabled
BF1 MODE:
3-Pole
BF1 SOURCE:
SRC 1
BF1 USE AMP SUPV:
Yes
BF1 USE SEAL-IN:
Yes
BF1 3-POLE INITIATE:
Off
BF1 BLOCK:
Off
BF1 PH AMP SUPV
PICKUP: 1.050 pu
BF1 N AMP SUPV
PICKUP: 1.050 pu
BF1 USE TIMER 1:
Yes
BF1 TIMER 1 PICKUP
DELAY: 0.000 s
BF1 USE TIMER 2:
Yes
BF1 TIMER 2 PICKUP
DELAY: 0.000 s
T60 Transformer Protection System
5.6 GROUPED ELEMENTS

5.6.10 BREAKER FAILURE (ANSI 50BF)


BREAKER FAILURE 1(6)
Range: Disabled, Enabled
Range: 3-Pole, 1-Pole
Range: SRC 1, SRC 2, SRC 3, SRC 4, SRC 5, SRC 6
Range: Yes, No
Range: Yes, No
Range: FlexLogic operand
Range: FlexLogic operand
Range: 0.001 to 30.000 pu in steps of 0.001
Range: 0.001 to 30.000 pu in steps of 0.001
Range: Yes, No
Range: 0.000 to 65.535 s in steps of 0.001
Range: Yes, No
Range: 0.000 to 65.535 s in steps of 0.001
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