MODULE TITLE : ELECTRICAL SUPPLY AND DISTRIBUTION SYSTEMS TOPIC TITLE : THE OPERATION OF 3-PHASE TRANSFORMERS IN PARALLEL AND GENERATORS ON INFINITE BUSBARS TUTOR MARKED ASSIGNMENT 2 NAME........................................................................................................................................ ADDRESS ................................................................................................................................. ................................................................................................................................................... ................................................................................................................................................... ...................................................... HOME TELEPHONE ..................................................... EMPLOYER.............................................................................................................................. ................................................................................................................................................... ................................................................................................................................................... ...................................................... WORK TELEPHONE...................................................... ESD - 2 - 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. For a Yd1 transformer: (a) draw the connection diagram (b) show how the connections must be modified to allow parallel operation with a Yd11 transformer (c) draw a phasor diagram for the modified connection. 2. In your own words, state the three essential and two highly desirable conditions which must be fulfilled for two 3-phase transformers to operate satisfactorily in parallel. State briefly what you think may be the possible consequences of not complying with these conditions. 3. (a) Two single-phase transformers have the following impedances referred to the secondary side. Unit A rated 250 kVA (0.09 + j2.7) Ω Unit B rated 400 kVA (0.04 + j1.6) Ω Determine the load taken by each machine as a percentage of its rating when they share a common load of 500 kVA at 0.73 p.f. lag. 2 Teesside University Open Learning (Engineering) © Teesside University 2011(b) Transformer A is rated at 300 kVA with an impedance of (0.09 + j0.18) Ω Transformer B is rated at 200 kVA with an impedance of (0.09 + j0.23) Ω If these transformers are connected in parallel to supply a common load, determine the percentage overload on B when A supplies its full load at p.f. 0.45 lag. 4. From the operating chart shown in FIGURE 15 of lesson ESD - 2 - 2, determine the following performance limitations for a generator: (a) where the power limit and the MVA limit coincide; (i) the power factor (ii) the load angle (iii) the MVAr output (b) where the power limit and the stability margin coincide; (i) the p.u. excitation (ii) the MVA output. 3 Teesside University Open Learning (Engineering) © Teesside University 20115. A 3-phase synchronous generator rated at 570 MVA is connected to an infinite busbar. Using the data given in the table below, plot the capacity chart of the generator. Quantity Value Synchronised Reactance Excitation Limit Maximum Margin Turbine Power Limit Stability Margin 2.0. p.u. 2.8 p.u. 570 MVA 500 MW 10% Full Load Power 4 Teesside University Open Learning (Engineering) © Teesside University 2011Teesside University Open Learning (Engineering) © Teesside University 2011 Question No.