Posted: September 18th, 2017

MODULE TITLE : ENGINEERING SCIENCE

TOPIC TITLE : A.C. CIRCUITS

TUTOR MARKED ASSIGNMENT 4 (v2.1)

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ENS – 4 – TMA (v2.1)

© Teesside University 2011

Student declaration:

I declare that all the work submitted is my own work and that no part of it has been copied from

any other source without full acknowledgement and complies with the University’s guiding

principles as stated in the Regulations Relating To Academic Misconduct*.

Student signature:………………………………………………………………………………………..

Date: ……………………………………………………………………………………….

Student code: ……………………………………………………………………………………….

Email: ……………………………………………………………………………………….

*http://www.tees.ac.uk/docs/index.cfm?folder=Student%20Regulations&name=Academic%20Regulations

Published by Teesside University Open Learning (Engineering)

School of Science & Engineering

Teesside University

Tees Valley, UK

TS1 3BA

+44 (0)1642 342740

All rights reserved. No part of this publication may be reproduced, stored in a

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photocopying, recording or otherwise without the prior permission

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This book is sold subject to the condition that it shall not, by way of trade or

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prior consent in any form of binding or cover other than that in which it is

published and without a similar condition including this

condition being imposed on the subsequent purchaser.

IMPORTANT

Before you start please read the following instructions carefully.

1. This assignment forms part of the formal assessment for this module. If

you fail to reach the required standard for the assignment then you will be

allowed to resubmit but a resubmission will only be eligible for a Pass

grade, not a Merit or Distinction.

You should therefore not submit the assignment until you are reasonably

sure that you have completed it successfully. Seek your tutor’s advice if

unsure.

2. Ensure that you indicate the number of the question you are answering.

3. Make a copy of your answers before submitting the assignment.

4. Complete all details on the front page of this TMA and return it with

the completed assignment including supporting calculations where

appropriate. The preferred submission is via your TUOL(E) Blackboard

account:

https://eat.tees.ac.uk

5. Your tutor’s comments on the assignment will be posted on Blackboard.

1

Teesside University Open Learning

(Engineering)

© Teesside University 2011

Assessment Criteria

This assignment will focus on a.c. circuits. The assignment forms Element 4

of the module’s assessment criteria that covers in part Learning Outcomes 2, 3

and 4 as indicated below.

MODULE LEARNING OUTCOMES

Knowledge and Understanding

1. Describe and explain static engineering systems.

2. Describe and explain simple d.c.and a.c.circuits

Cognitive and Intellectual Skills

3. Apply d.c. and a.c.theory to a variety of well defined circuits.

Practical and Professional Skills

Key Transferable Skills

4. Demonstrate numerical and statistical skills applied to engineering problems

relating to electrical and mechanical science.

2

Teesside University Open Learning

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© Teesside University 2011

PASS

A solution has been

developed to solve problems

but may include some minor

redundancies or errors.

MERIT

Criteria in excess of the pass

grade.

Suitable equations identified

and applied to produce

correct solutions with the

minimum of assistance.

DISTINCTION

Criteria in excess of the

merit grade.

Problems have been solved

independently with the

importance of

interdependence recognised.

1. For the circuit given in FIGURE 1 the power factor is 0.72 lagging and

the power dissipated is 375 W.

FIG. 1

Determine the:

(i) apparent power

(ii) reactive power

(iii) the magnitude of the current flowing in the circuit

(iv) the value of the impedance Z and state whether circuit is inductive or

capacitive.

2. A 50 kW load operates from a 60 Hz 10 kV rms line with a power factor

of 60% lagging. Determine the capacitance that must be placed in

parallel with the load to achieve a 90% lagging power factor.

3. A series RLC circuit is connected to a 5 V supply, the frequency of the

supply is adjusted to give a maximum current of 11.9 mA at 2.5 kHz. The

Q factor is 70. Determine the component values of the circuit.

120 V

Z R = 10 Ω

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Teesside University Open Learning

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© Teesside University 2011

4. A single phase transformer has the following rating: 120 kVA,

2000 V/100 V, 60 Hz with 1000 primary turns.

Determine:

(a) the secondary turns

(b) the rated primary and secondary currents

(c) the maximum flux

(d) given a maximum flux density of 0.25 T, the cross-sectional area of

the core.

5. An a.c. voltage, V, comprises of a fundamental voltage of 100 V rms at a

frequency of 120 Hz, a 3rd harmonic which is 20% of the fundamental, a

5th harmonic which is 10% of the fundamental and at a phase angle of

1.2 radians lagging.

(i) Write down an expression for the voltage waveform.

(ii) Sketch the waveforms of the harmonic components.

(iii) Determine the voltage at 20 ms.

(iv) Given an ideal V = 100 V rms, what is the percentage error at 20 ms?

4

Teesside University Open Learning

(Engineering)

© Teesside University 2011

Teesside University Open Learning

(Engineering)

© Teesside University 2011

Question

No.

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