-SQA-SCOTTISH QUALIFICATIONS AUTHORITY HIGHER NATIONAL UNIT SPECIFICATION GENERAL INFORMATION

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1 -SQA-SCOTTISH QUALIFICATIONS AUTHORITY HIGHER NATIONAL UNIT SPECIFICATION GENERAL INFORMATION -Unit Number Superclass- -Title- XL SYNCHRONOUS MACHINES DESCRIPTION- GENERAL COMPETENCE FOR UNIT: of synchronous machines. Evaluating the operating performance OUTCOMES 1. explain the construction and principle of operation of synchronous machines; 2. explain and evaluate the operating characteristics of a synchronous generator; 3. explain and evaluate the operating characteristics of a synchronous motor. CREDIT VALUE: 1 HN Credit ACCESS STATEMENT: Access to this unit is at the discretion of the centre. However, it would be beneficial if the candidate had knowledge of field theory and basic electrical circuits. This may be evidenced by possession of: NC Module: Electrical Machines Principles Electrical Motor Applications HN unit: Electrical and Magnetic Fields Single Phase AC Networks Three Phase Systems or similar qualifications or experience

2 For further information contact: Committee and Administration Unit, SQA, Hanover House, 24 Douglas Street, Glasgow G2 7NQ. Additional copies of this unit may be purchased from SQA (Sales and Despatch section). At the time of publication, the cost is 1.50 (minimum order 5.00). 2

3 HIGHER NATIONAL UNIT SPECIFICATION STATEMENT OF STANDARDS UNIT NUMBER: UNIT TITLE: SYNCHRONOUS MACHINES Acceptable performance in this unit will be the satisfactory achievement of the standards set out in this part of the specification. All sections of the statement of standards are mandatory and cannot be altered without reference to SQA. OUTCOME 1. EXPLAIN THE CONSTRUCTION AND PRINCIPLE OF OPERATION OF SYNCHRONOUS MACHINES PERFORMANCE CRITERIA (a) (b) (c) Constructional features of a synchronous machine are clearly explained. Principles of operation of a synchronous machine operating as a motor and generator are correctly explained. Methods of excitation are clearly explained. RANGE STATEMENT Synchronous machines: cylindrical rotor; salient pole. Excitation: permanent magnet; brushless. EVIDENCE REQUIREMENTS Written/graphical and/or oral evidence indicating an understanding of the constructional features, principles of operation and methods of excitation of a synchronous machine, as specified in performance criteria (a) to (c). 3

4 OUTCOME 2. EXPLAIN AND EVALUATE THE OPERATING CHARACTERISTICS OF A SYNCHRONOUS GENERATOR PERFORMANCE CRITERIA (a) (b) (c) (d) The main operating characteristics of a synchronous generator are correctly explained. An equivalent circuit is used to correctly evaluate the performance of a synchronous generator. Operation of a synchronous generator connected to an infinite bus bar is clearly described. Synchronous generators synchronisation procedures are clearly described. RANGE STATEMENT Operating characteristics: operation with constant terminal voltage; variable excitation and variable load; operation with constant excitation; variable terminal voltage and variable load. EVIDENCE REQUIREMENTS Written and/or oral evidence of the candidate s ability to explain and understand the operating characteristics of a synchronous generator, as specified in performance criteria (a) and (b). Performance evidence of the candidate s ability to describe the operations and procedures of the synchronous generators as detailed in performance criteria (c) and (d). OUTCOME 3. EXPLAIN AND EVALUATE THE OPERATING CHARACTERISTICS OF A SYNCHRONOUS MOTOR PERFORMANCE CRITERIA (a) (b) (c) (d) The main operating characteristics of a synchronous motor are determined correctly by test. An equivalent circuit is used to correctly evaluate the performance of a synchronous motor. Statement of two examples of the application of synchronous motors is correct. Starting methods of synchronous motors are correctly described. 4

5 RANGE STATEMENT Operating characteristics: operation with variable excitation and constant load torque (V-form characteristics); operation with variable load torque and constant excitation (angular characteristics). Starting methods: induction motor; variable frequency supply. EVIDENCE REQUIREMENTS Written and/or oral evidence of the candidate s ability to explain and understand the operating characteristics of a synchronous motor, and to describe starting methods of synchronous motors, as specified in performance criteria (a) - (d). Performance evidence of the candidate s ability to evaluate a synchronous motor as detailed in performance criterion (b). MERIT To gain a pass in this unit, a candidate must meet the standards set out in the outcomes, performance criteria, range statements and evidence requirements. To achieve a merit in this unit, a candidate must demonstrate a superior or more sophisticated level of performance. This may be demonstrated by: (i) (ii) (iii) consistently high level of accuracy; outstanding analytical and practical skills; consistent logical presentation of work ASSESSMENT In order to achieve this unit, candidates are required to present sufficient evidence that they have met all the performance criteria for each outcome within the range specified. Details of these requirements are given for each outcome. The assessment instruments used should follow the general guidance offered by the SQA assessment model and an integrative approach to assessment is encouraged. (See references at the end of support notes). Accurate records should be made of the assessment instruments used showing how evidence is generated for each outcome and giving marking schemes and/or checklists, etc. Records of candidates achievements should be kept. These records will be available for external verification. SPECIAL NEEDS Proposals to modify outcomes, range statements or agreed assessment arrangements should be discussed in the first place with the external verifier. 5

6 Copyright SQA 1997 Please note that this publication may be reproduced in whole or in part for educational purposes provided that: (i) (ii) no profit is derived from the reproduction; if reproduced in part, the source is acknowledged. 6

7 HIGHER NATIONAL UNIT SPECIFICATION SUPPORT NOTES UNIT NUMBER: UNIT TITLE: SYNCHRONOUS MACHINES SUPPORT NOTES: This part of the unit specification is offered as guidance. None of the sections of the support notes is mandatory. NOTIONAL DESIGN LENGTH: SQA allocates a notional design length to a unit on the basis of time estimated for achievement of the stated standards by a candidate whose starting point is as described in the access statement. The notional design length for this unit is 40 hours. The use of notional design length for programme design and timetabling is advisory only. PURPOSE The purpose of this unit is to enable candidates to gain some knowledge and understanding of sychronous machines. This unit is intended to provide candidates with both theoretical and practical skills required for dealing with synchronous machines. CONTENT/CONTEXT Teaching should be practically-orientated and takes place in both an electrical laboratory and classroom setting. Formal lectures should be kept to a minimum and extensive use should be made of tutorials, reference handouts, visual aids and practical exercises. Corresponding to Outcomes: Outcome 1 The candidate should be able to distinguish between the constructional features of the 2 types of synchronous machines. The principle of operation of a synchronous machine should be explained clearly and consideration should be given to methods of excitation. Outcome 2 This outcome should provide the candidate with some knowledge and understanding of how to evaluate the performance of a synchronous generator based on the use of the equivalent circuit and to develop its main operating characteristics. The candidate should made aware of the operation of a synchronous generator when connected to an infinite busbar and consideration should be given to it s synchronisation procedures. 7

8 Outcome 3 This outcome should provide the candidate with some knowledge and understanding of how to evaluate the performance of a synchronous motor based on the use of the equivalent circuit and to develop its main operating characteristics. The candidate should be made aware of the operation of the different starting methods of a synchronous motor. APPROACHES TO GENERATING EVIDENCE This unit should be taught in an environment where access to laboratory equipment is readily available. The unit should be delivered in the order the outcomes are listed so that the basic theory is dealt with prior to consideration of practical aspects. The use of written tests coupled with suitable laboratory experiments are appropriate methods for assessing this unit. Where calculations are performed, it is recommended that emphasis should be placed on the calculation methods and flexibility should be exercised where a candidate makes arithmetical errors. ASSESSMENT PROCEDURES Structured questions and laboratory exercises are recommended for assessing outcomes. Centres may use the Instruments of Assessment which are considered by tutors/trainers to be most appropriate. PROGRESSION Achievement of this unit should provide a sound basis for candidates entering industry or going on to studying more specialised programmes in electrical power engineering. REFERENCES 1. Guide to unit writing. 2. For a fuller discussion on assessment issues, please refer to SQA s Guide to Assessment. 3. Information for centres on SQA s operating procedures is contained in SQA s Guide to Procedures. 4. For details of other SQA publications, please consult SQA s publications list. Copyright SQA 1997 Please note that this publication may be reproduced in whole or in part for educational purposes provided that: (i) no profit is derived from the reproduction; 8

9 (ii) if reproduced in part, the source is acknowledged. 9