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Byju's Answer

Standard XII

Physics

Phasor

Consider the ...

Question

Consider the following statements for the fully transposed transmission line.

Statement (1): Positive and negative sequence impedance are equal.
Statement (II): zero sequence impedance is much smaller than the positive or negative sequence impedance.

Both statements are true

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Statement I is true, Statement II is false

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Statement I is false, Statement II is true

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Bothe statement are false

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Solution

The correct option is B Statement I is true, Statement II is false
For the fully transposed transmission line,

Positive sequence impedance $Z_{1} = Z_{s} - Z_{m}$

Negative sequence impedance $Z_{2} = Z_{s} - Z_{m}$

Zero-sequence impedance, $Z_{s} = Z_{s} + 2 Z_{m} + 3 Z_{n}$

Where, $Z_{s} =$ Self impedance/ph

$Z_{m} =$ Mutual impedance/ph

If the system voltages are unbalanced, we have a neutral current, $I_{n}$ flowing through the neutral (ground) having impedance $Z_{n}$

From above equations, we can say

1. Positive and negative sequence impedance are equal.

2. Zero sequence impedance is much larger than the positive or negative sequence impedance.

$∴$ Statement (I) is true and statement (II) is false.

Suggest Corrections

Similar questions

Q. Consider the following statements for the fully transposed transmission line.
Statement (I) : Positive and negative sequence impedance are equal.
Statement (II) : Zero sequence impedance is much smaller than the positive or negative sequence impedance.

Q. The positive, negative and zero sequence impedance of 3-

ϕ

generator are 0.4 pu, 0.3 and 0.2 pu respectively. For a line to line fault with fault impedance

Z_{f}

and fault current is

I_{f 1} = 0.2 I_{f}

, where

I_{f}

is the fault current with zero fault impedance, then value of

Z_{f}

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Q. The series impedance matrix of a short

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transmission line in phase coordinates is represented by Z,

w h e r e, Z = ⎡ ⎢ ⎣ \begin{matrix} Z_{s} & Z_{m} & Z_{m} Z_{m} & Z_{s} & Z_{m} Z_{m} & Z_{m} & Z_{s} \end{matrix} ⎤ ⎥ ⎦

If the positive sequence impedance is

(4 + j 16) Ω

and zero sequence impedance is

(8 + j 32) Ω

, then value of imaginary of

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is ________

Ω

Q. The series impendance matrix of a short three-phase transmission line in phase coordinates is

⎡ ⎢ ⎣ \begin{matrix} Z_{s} & Z_{m} & Z_{m} Z_{m} & Z_{s} & Z_{m} Z_{m} & Z_{m} & Z_{s} \end{matrix} ⎤ ⎥ ⎦

. If the positive sequence impedance is (1 + j10)

Ω

, and the zero sequence impedance is (4 + j31)

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Q. A 3-phase transmission line is shown in figure:

Voltage drop across the transmission line is given by the following equation:

⎡ ⎢ ⎣ \begin{matrix} Δ V_{a} Δ V_{b} Δ V_{c} \end{matrix} ⎤ ⎥ ⎦ = ⎡ ⎢ ⎣ \begin{matrix} Z_{s} & Z_{m} & Z_{m} Z_{m} & Z_{s} & Z_{m} Z_{m} & Z_{m} & Z_{s} \end{matrix} ⎤ ⎥ ⎦ ⎡ ⎢ ⎣ \begin{matrix} I_{a} I_{b} I_{c} \end{matrix} ⎤ ⎥ ⎦

Shunt capacitance of the line can be neglected. If the line has positive sequence impedance of 15

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Consider the following statements for the fully transposed transmission line. Statement (1): Positive and negative sequence impedance are equal. Statement (II): zero sequence impedance is much smaller than the positive or negative sequence impedance.

Consider the following statements for the fully transposed transmission line.

Statement (1): Positive and negative sequence impedance are equal.
Statement (II): zero sequence impedance is much smaller than the positive or negative sequence impedance.