Login Registrieren

Warning: foreach() argument must be of type array|object, bool given in /var/www/html/web/app/themes/studypress-core-theme/template-parts/header/mobile-offcanvas.php on line 20

Power System Analysis and Design

Mulukutla S Sarma, J D Glover, Thomas Overbye

Computer Science

6th Edition · 925 pages

ISBN: 9781305632134

Chapter 3: 24MCQ (page 142)

It is stated that
(i) balanced three-phase circuits can be solved in per unit on a per-phase basis after converting-load impedances to equivalent Y impedances.
(ii) Base values can be selected either on a per-phase basis or on a three phase basis.
(a) Both statements are true.
(b) Neither is true.
(c) Only one of the above is true.

Short Answer

Expert verified

Therefore, the correct option is (a) both statements are true.

Step by step solution

01

Check first statement

The per unit analysis is performed on the per phase system converting from three phase system. This is the advantage of per-unit analysis.

It is easy to perform per-unit analysis on $∆$ connection, when it is converted to Y-connection, and then into single phase.

Hence, statement (i) is correct.

02

Check second statement

The base value will be same, either it is selected from single phase system or from three phase system.

So, statement (ii) is correct.

Hence, the correct option is (a) both statements are true.

Unlock Step-by-Step Solutions & Ace Your Exams!

Full Textbook Solutions
Get detailed explanations and key concepts
Unlimited Al creation
Al flashcards, explanations, exams and more...
Ads-free access
To over 500 millions flashcards
Money-back guarantee
We refund you if you fail your exam.

Start your free trial

Over 30 million students worldwide already upgrade their learning with Vaia!

One App. One Place for Learning.

All the tools & learning materials you need for study success - in one app.

Get started for free

Most popular questions from this chapter

The transformer of Problem 3.16 is supplying a rated load of 50kVAat a rated secondary voltage of 240Vand at 0.8 power factor lagging. Neglect the transformer exciting current. (a) Determine the input terminal voltage of the transformer on the high-voltage side (b) Sketch the corresponding phasor diagram. (c) If the transformer is used as a step-down transformer at the load end of a feeder whose impedance is $(0.5 + j 2.0) Ω$ , find the voltage $V_{s}$ and the power factor at the sending end of the feeder.

A three-phase transformer is rated $1000 MVA$ , $220 Y / 22 Δ kV$ . The Y-equivalent short-circuit impedance, considered equal to the leakage reactance, measured on the low-voltage side is $0.1 Ω$ .Compute the per-unit reactance of the transformer. In a system in which the base on the high-voltage side of the transformer is $100 MVA$ , $230 kV$ , what value of the per-unit reactance should be used to represent this transformer?

The ideal transformer windings are eliminated from the per-unit equivalent circuit of a transformer.

(a) True (b) False

To convert a per-unit impedance from "old" to "new" base values the equation to be used is

(a) $Z_{p . u n e w} = Z_{p . u . o l d} {(\frac{V_{b a s e o l d}}{V_{b a s e n e w}})}^{2} (\frac{S_{b a s e n e w}}{S_{b a s e o l d}})$

(b)role="math" localid="1655898634705" $Z_{p . u n e w} = Z_{p . u . o l d} {(\frac{V_{b a s e o l d}}{V_{b a s e n e w}})}^{2} (\frac{S_{b a s e n e w}}{S_{b a s e o l d}})$

(c)role="math" localid="1655898620711" $Z_{p . u n e w} = Z_{p . u . o l d} {(\frac{V_{b a s e o l d}}{V_{b a s e n e w}})}^{2} (\frac{S_{b a s e o l d}}{S_{b a s e n e w}})$

An infinite bus, which is a constant voltage source, is connected to the primary of the three-winding transformer Of Problem 3.53. A $7.5 - M V A, 13.2 k V$ synchronous motor with a sub transient reactance of 0.5 per unit is connected to the transformer secondary. A localid="1656746464858" $5 M W, 2.3 k V$ , three- phase resistive load is connected to the tertiary. Choosing a base of localid="1656746481214" $66 k V$ and localid="1656746490341" $15 M V A$ in the primary, draw the impedance diagram of the system showing per-unit Neglect transformer exciting current, phase shifts, and all resistances except the resistive load.

Problem 3.53

The ratings of a three-phase, three-winding transformer are

Primary: Y connectedlocalid="1656746552467" $66 k V, 15 M V A$ ,

Secondary: localid="1656746559217" $Y$ connectedlocalid="1656746566136" $13.2 k V, 10 M V A$ ,

Tertiary: localid="1656746571916" $Δ$ connectedlocalid="1656746577941" $2.3 k V, 5 M V A$ ,

Neglecting resistances and exciting current, the leakage reactance’s are:

localid="1656746584806" $X_{P S} = 0.09$ per unit on alocalid="1656746592283" $15 M V A, 66 k V$ base

localid="1656746599787" $X_{P T} = 0.08$ per unit on alocalid="1656746606719" $15 M V A, 66 k V$ base

localid="1656746614327" $X_{S T} = 0.05$ per unit on alocalid="1656746620958" $10 M V A, 13.2 k V$ base

Determine the reactance’s of the per-phase equivalent circuit using a base oflocalid="1656746628095" $15 M V A,$ and localid="1656746635563" $66 k V$ for the primary.

See all solutions

Recommended explanations on Computer Science Textbooks

Problem Solving Techniques

Read Explanation

Game Design in Computer Science

Read Explanation

Computer Organisation and Architecture

Read Explanation

Data Structures

Read Explanation

Computer Network

Read Explanation

Databases

Read Explanation

View all explanations

What do you think about this solution?

We value your feedback to improve our textbook solutions.

Study anywhere. Anytime. Across all devices.

Sign-up for free