Negative Sequence Current - GE T60 Instruction Manual

GROUPED ELEMENTS
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 + 0.05) = 0.15 pu, IR0 = abs(3 × 0.033 – (0.05)) = 0.05 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 100% of the restraining current.
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.
5

5.7.10 Negative sequence current

5.7.10.1 Menu
SETTINGS  GROUPED ELEMENTS  SETTING GROUP 1(6)  NEGATIVE SEQUENCE CURRENT
 NEGATIVE SEQUENCE
 CURRENT
For information on the negative sequence time overcurrent curves, see the Inverse TOC Curve Characteristics section
earlier.
5-290
 NEG SEQ TOC1



 NEG SEQ TOC3


 NEG SEQ IOC1



 NEG SEQ IOC3


 NEG SEQ DIR OC1



 NEG SEQ DIR OC3


See below
See page 5-291
See page 5-292
T60 TRANSFORMER PROTECTION SYSTEM – INSTRUCTION MANUAL
CHAPTER 5: SETTINGS