CHAPTER 5: SETTINGS
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.
5.7.8 Negative sequence current
5.7.8.1 Menu
SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) NEGATIVE SEQUENCE CURRENT
NEGATIVE SEQUENC
CURRENT
The F60 provides two negative-sequence time overcurrent elements, two negative-sequence instantaneous overcurrent
elements, and two negative-sequence directional overcurrent elements. For information on the negative sequence time
overcurrent curves, see the Inverse TOC Curve Characteristics section earlier.
5.7.8.2 Negative sequence time overcurrent (ANSI 51Q, IEC PTOC)
SETTINGS GROUPED ELEMENTS SETTING GROUP 1(6) NEGATIVE SEQUENCE CURRENT NEG SEQ TOC1(2)
NEG SEQ TOC1
F60 FEEDER PROTECTION SYSTEM – INSTRUCTION MANUAL
NEG SEQ TOC1
NEG SEQ TOC2
NEG SEQ IOC1
NEG SEQ IOC2
NEG SEQ DIR OC1
NEG SEQ DIR OC2
NEG SEQ TOC1
FUNCTION: Disabled
NEG SEQ TOC1 SIGNAL
SOURCE: SRC 1
GROUPED ELEMENTS
See below
See page 5-248
See page 5-249
Range: Disabled, Enabled
Range: SRC 1, SRC 2, SRC 3, SRC 4
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