MODULE TITLE : ELECTRICAL SUPPLY AND DISTRIBUTION SYSTEMS TOPIC TITLE : TYPES OF ELECTRICAL DISTRIBUTION SYSTEMS, TARIFFS AND SWITCHING EQUIPMENT TUTOR MARKED ASSIGNMENT 1 NAME........................................................................................................................................ ADDRESS ................................................................................................................................. ................................................................................................................................................... ................................................................................................................................................... ...................................................... HOME TELEPHONE ..................................................... EMPLOYER.............................................................................................................................. ................................................................................................................................................... ................................................................................................................................................... ...................................................... WORK TELEPHONE...................................................... ESD - 1 - TMA (v1) © Teesside University 2011 THIS BOX MUST BE COMPLETED Student Code No. .................................................................................................... Student's Signature .................................................................................................. Date Submitted ........................................................................................................ Contact e-mail .........................................................................................................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 retrieval system, or transmitted, in any form or by any means, electronic, mechanical, photocopying, recording or otherwise without the prior permission of the Copyright owner. This book is sold subject to the condition that it shall not, by way of trade or otherwise, be lent, re-sold, hired out or otherwise circulated without the publisher's 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 20111. (a) What is meant by 'discrimination' when applied to protective relays on an electrical supply system and why is it necessary? (b) Which relay on the radial feeder shown in the diagram will have the shortest operating time and operate first in the event of the fault shown? (c) Which types of relay would be found on a ring feeder and why? 2. (a) State briefly the main advantages and disadvantages of radial and ring feeders. (b) Explain the relationship between power and energy and hence determine the number of megajoules in one unit of electricity. 3. (i) A medium-sized clothing factory takes its supply at low voltage and has the following meter readings for the month of September. MD (day) 428 kW MD (night) 87 kW kWh (day) 72180 kWh (night) 10060 If the average power factor is 0.843, find the bill for the month, using the supplier's tariff shown in lesson ESD - 1 - 2. A B C D E 2 Teesside University Open Learning (Engineering) © Teesside University 2011(ii) A large continuous process foundry works a night shift and takes its supply at high voltage. For the month of December the following meter readings are recorded. MD (day) 1792 kW (night) 1607 kW Units (day) 224368 kWh (night) 289560 kWh Reactive (day) 131140 kVArh (night) 195510 kVarh Chargeable Capacity 2123 kVA Find the average power factor for the month and calculate the electricity bill. 4. The diagram below shows the single phase equivalent circuit of a 275 kV, 3-phase source connected to a line and a circuit breaker, and a fault on the system is shown. Calculate: (a) the frequency of the recovery voltage transient (b) the maximum voltage to appear across the CB contacts (c) the average rate of rise of recovery voltage transient. Fault 0.27µF 12.3 mH 3 Teesside University Open Learning (Engineering) © Teesside University 20115. With reference to the following high voltage fused and circuit breakers, briefly describe the principle of arc suppression, control and interruption of the circuit. (a) oil CB (b) air blast CB (c) vacuum (d) SF6 CB (e) HRC liquid fuse (f) HRC expulsion fuse. 4 Teesside University Open Learning (Engineering) © Teesside University 2011Teesside University Open Learning (Engineering) © Teesside University 2011 Question No.