Electotechnics N6 — Document

December 2023 — N6 — Electotechnics

N6 2023 Nated Engineering

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🎯 100 marks ⏱️ 3h 📄 5 pages 📝 35 items found 📚 1 topics

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Questions — A Preview of What to Expect in the Document

This section provides a quick preview of questions from the document. It may not display every question or the complete wording of each one. For the full content, including diagrams, tables and other information, view the original PDF above.

Q1— Section header —

1.1A DC series motor is a variable speed motor. sing suitable formulae, explain why the current drawn by this motor increases when the motor is mechanically loaded. (4\

1.2A 250 V, DC series motor runs at 1 000 r/min while drawing a current of 40 amperes from the supply. The resistances of the armature and series field are 0,25 ohms and 0,1 ohms respectively. When a 0,2

1.2.1Draw TWO fully labelled circuit diagrams to show the DC series motor before and after the diverter resistor is connected. (2\

1.2.2Calculate the speed at which the motor will run after the diverter resist r is connected. (10\ [16]16

Q2— Section header —

2.1An expression for the instantaneous value of the current (8\

2.2The power factor of the circuit ( lso state the nature of the power factor\ (5\

2.3The energy dissipated in the circuit in 10 milli seconds (1\

2.4Draw a large vector diagram clearly showing the voltages and currents for the fundamental as well as the harmonic component (2\ [16] (8080096\ Copyright reserved16

Q3— Section header —

3.1State TWO constant losses occurring in a transformer and state precisely where each occurs. (4\

3.2A 250 kVA, 3 300/240 V, single phase transformer produces a maximum efficiency of 92% at 80% of full load. or a power factor of 0,85 lagging , calculate

3.2.1The iron losses (2\

3.2.2The full load copper losses (2\

3.2.3The percentage resistance (4\

3.2.4The per unit full load voltage regulation of the transformer when it works at unity power factor (2\ [14]14

Q4— Section header —

4.1Explain what is meant by distribution factor of a synchronous alternator. (3\

4.2The following information applies to a three phase, star connected alternator: Open circuit terminal EMF

Q5— Section header —

5.1The percentage slip at which the motor is operating (3\

5.2The rotor copper loss (2\

5.3The power input to the motor if the total losses occurring in the stator amounts to 1 080 watts (3\ (8080096\ Copyright reserved

5.4The current drawn from the supply (2\

5.5The efficiency of the motor (3\ [13]13

Q6— Section header —

6.1Draw a neat, fully labelled vector diagram clearly showing the maximum demand before and after the installation of the capacitor bank (2\

6.2Determine the size of the capacitor bank (5\

6.3Determine the cost of the capacitor bank if it sells for R295 per kVAr (2\

6.4Determine how many months it will take to pay off the capacitor bank using only the savings in maximum demand charges. Assume that the consumer pays a maximum demand charge of R132 per kVA. (4\ [13]13

Q7— Section header —

7.1The current at the receiving end (8\

7.2The voltage at the receiving end (3\

7.3The power in MW available for the development (2\ [13] TOTAL: 100 (8080096\13

Topics Identified

Business Plan

Mark Allocation

Total100 marks

Sections16 + 16 + 14 + 15 + 13 + 13 + 13 = 100 marks

Paper information

TitleDocument

SubjectElectotechnics

LevelN6

Document typeQuestion paper

Year2023

MonthDecember

Pages10

Downloads3

Examination context

Decade2020s

Years ago3y

SeasonSummer (SH)

Start dayFriday

Exam periodDecember 2023

Days since exam1,043

About Electotechnics examination preparation

This TVET examination resource can be used as part of a structured revision programme. Past papers are most useful when learners attempt questions independently, work within a realistic time limit, and review their answers afterwards.

How to use this resource for revision

A TVET past examination paper is most useful when it is treated as an active revision exercise. Try the questions yourself before checking the corresponding memorandum. Where you make an error, identify the reason — was it a knowledge gap, a calculation mistake, an interpretation issue, or an examination technique problem?

For stronger examination practice, complete the paper without unnecessary interruptions and keep track of the questions that take the most time. Afterwards, review the memorandum and separate knowledge gaps from mistakes caused by interpretation, calculation, structure, or examination technique.

understanding question requirements

applying subject knowledge

working under time constraints

checking answers

identifying revision priorities

A practical revision approach

Start by completing the resource without looking at the memorandum. Review incorrect and incomplete answers afterwards and make a short revision list based on the areas that caused difficulty.

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