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In which type of fault, zero sequence currents do not exist?

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DDA JE (E&M) Official Paper (Held on 25 April 2018)
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  1. Line to Line
  2. Line-Line to Ground
  3. Line to Ground
  4. Line-Line-Line to Ground

Answer (Detailed Solution Below)

Option 1 : Line to Line
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Detailed Solution

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Line to Line fault:

When two conductors of a 3-phase system are short-circuited line to line fault occurs.

IR = 0

IF = IY = -IB

...........(i)

From equation (i), we found that zero sequence currents do not exist in the LL fault.

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Q1.At the terminal of a 3ϕ, 6.6 kV, 10 MVA alternator, a load R = 200 Ω is connected between two phases, and other phase is kept open. The sequence impedance of the alternator is Z1 = Z2 = j 5Ω and Z0 = j2Ω. What is the current through the load resistance?
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Q1.Which of the following characteristics is associated with a distance relay used for fault protection?
Q2.Selectivity in a protection relay system refers to:
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