MyQuestionIcon

1

You visited us 1 times! Enjoying our articles? Unlock Full Access!

Combination of Resistors

A 6.6 kV, 3-p...

Question

A 6.6 kV, 3-phase, 10 MVA alternator has positive, negative and zero sequence reactances as j0.05 p.u. j0.0375 p.u. and j0.045 p.u. respectively. A double line to ground faults occurs, then the magnitude of positive sequence voltage is

A

0.29 p.u

Right on! Give the BNAT exam to get a 100% scholarship for BYJUS courses

B

6.45 p.u.

No worries! We‘ve got your back. Try BYJU‘S free classes today!

C

14.19 p.u.

No worries! We‘ve got your back. Try BYJU‘S free classes today!

D

can not determined

No worries! We‘ve got your back. Try BYJU‘S free classes today!

Open in App

Solution

The correct option is A 0.29 p.u

$I_{a 1} = \frac{E}{Z_{1} + \frac{Z_{2} Z_{0}}{Z_{2} + Z_{0}}}$

$= \frac{1}{j 0.05 + \frac{j 0.0375 \times j 0.045}{j 0.0375 + j 0.045}}$

$∴ I_{a 1} = - (I_{a 2} + I_{a 0}))$

$= - j 14.19 p . u .$

$I_{a 0} = - I_{a_{1}} \frac{j 0.0375}{j 0.0375 + j 0.045}$

$= j 6.45 p . u .$

$V_{a 1} = V_{a 2} = V_{a 0} = j 0.045 \times j 6.45$

$= - 0.29 p . u .$

Suggest Corrections

thumbs-up

0

Similar questions

Q. The positive , negative and zero sequence impedance of

3 - ϕ

generator are 0.4 pu, 0.3 pu 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}

I_{f}

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

Z_{f}

will be ___ pu.

Q. A synchronous generator is rated 25 MVA, 11 kV. It is star connected with neutral point solidly grounded. The generator is operating at no-load rated voltage. Positive, negative and zero sequence reactance are 0.2 p.u., 0.2 p.u. and 0.08 p.u. respectively. A line to line fault occurs on b and c phase of generator. Then the magnitude of fault current will be

Q. A 25 MVA, 13.2 kV alternator with solidly grounded netural has a substransient reactance of 0.25 p.u. The negative and zero sequence reactance are 0.35 and 0.1 p.u. respectively. A single line to ground fault occurs at the terminals of an unloaded alternator, then the fault current is

Q. Three 6.6 kV,

3 - Φ

, 10 MVA alternators are connected to a common bus. Each alternator has a positive, negative and zero sequence reactance as 0.15 p.u., 0.1 p.u., 0.05 p.u. respectively. A single line ground fault occurs at point F, as shown in figure below.

I_{f}

is the fault current when all the alternator neutrals solidly grounded.

I_{f}^{'}

is the fault current when only one neutral is solidly grounded and other two neutrals are isolated. Then the value of

∣ ∣ I_{f} - I_{f}^{'} ∣ ∣ =

Q. A 30 MVA, 3-phase, 50 Hz, 13.8 kV, star-connected synchronous generator has positive, negative and zero sequence reactances, 15%, 15% and 5% respectively. A reactance (X

_{n}

) is connected between the neutral of the generator and ground. A double line to ground fault takes place involving phase 'b' and 'c' with a fault impendance of j0.1 p.u.. The value of x

_{n}

(in p.u.) that will limit the positive sequence generator current to 4270 A is

View More

Join BYJU'S Learning Program

similar_icon

Related Videos

lock

Combination of Resistors_Tackle

PHYSICS

Watch in App

explore_more_icon

Explore more

Combination of Resistors

Standard X Physics

Join BYJU'S Learning Program

CrossIcon