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2011 HSC Notes from the Marking Centre – Electrotechnology

Contents

Introduction

This document has been produced for the teachers and candidates of the Stage 6 course in Electrotechnology. It contains comments on candidate responses to the 2011 Higher School Certificate examination, indicating the quality of the responses and highlighting their relative strengths and weaknesses.

This document should be read along with the relevant syllabus, the 2011 Higher School Certificate examination, the marking guidelines and other support documents developed by the Board of Studies to assist in the teaching and learning of Electrotechnology.

Teachers and candidates are reminded that – if candidates are undertaking the 240 hour VET Industry Curriculum Framework in Electrotechnology and they want to undertake the HSC examination in Electrotechnology – they need to be entered separately for the examination.

General comments

Teachers and candidates should be aware that examiners may ask questions that address the syllabus outcomes in a manner that requires candidates to respond by integrating the knowledge, understanding and skills they developed through studying the course.

Candidates need to be aware that the mark allocated to the question and the answer space (where this is provided on the examination paper) are guides to the length of the required response. A longer response will not in itself lead to higher marks. Writing far beyond the indicated space may reduce the time available for answering other questions.

Candidates need to be familiar with the Board’s Glossary of Key Words, which contains some terms commonly used in examination questions. However, candidates should also be aware that not all questions will start, with or contain, one of the key words from the glossary. Questions such as ‘how?’, ‘why?’ or ‘to what extent?’ may be asked, or verbs may be used that are not included in the glossary, such as ‘design’, ‘translate’ or ‘list’.

Section II

Question 16

  1. This question was answered well by the vast majority of candidates. Many candidates provided an appropriate example, such as ‘the yellow out-of-service tag indicates that the machine is out of order or being repaired’ or ‘the red tag is used for a machine that could prove dangerous to a user and has been isolated’.

  2. Many candidates named two people authorised to remove tags, such as the person who had first applied the tag or the supervisor of the person involved in the tagging. Some candidates went further, citing an industry practice where the names of the two people from a team are both on a tag to authorise removal.

    Few candidates understood the procedure for the tag’s removal.

Question 17

  1. Most candidates completed the resistors in series, the switch and fuse for circuit protection, although some located the fuse in parallel, where it would not protect the circuit. The placement of the meters was the most challenging aspect for many candidates with some placing the voltmeter in series with the supply, thus rendering the circuit non-functional.

    In poorer responses, candidates connected the ammeter in parallel with the supply, which would short circuit the remainder of the circuit. Teachers and candidates are reminded that a circuit in electrotechnology implies a functioning circuit.

  2. Most candidates correctly applied the V=IR formula to calculate the required current in the circuit. However, too many responses failed to specify that the current would be in amps. Units are considered to be a fundamental industry communication standard. Candidates are reminded that industry terminology should be used wherever possible.

Question 18

  1. Many candidates provided examples of verbal communication on the worksite. A few candidates did not respond correctly and provided a definition of verbal communication rather than an example, which was asked for. Some candidates gave only a single example of each form of communication where multiples were expected; however, quality single examples with an explanation were rewarded. Candidates referred to direct instruction from supervisors, training courses, instructions to and from co-workers or feedback on job progress.

    Teachers and candidates are reminded that the space provided for responses indicates the amount required to answer the question.

  2. Most candidates could provide examples of non-verbal worksite communication, although some used examples of written communication. Ideas such as flashing lights, flags or warning indicators were common responses.

  3. Many candidates did not provide enough examples of written communication. In better responses, candidates typically quoted instruction sheets, workplace plans or forms, job cards, invoices and receipts, quotations or reports of workplace incidents for occupational health and safety (OHS). Many candidates used the example of the danger tags shown in Question 17 as both written and non-verbal communication due to them containing text and having a colour. This was considered an acceptable response.

Question 19

  1. Most candidates provided accurate calculations of the distribution of current evenly between the 3 lamps, giving 2 amps each. Units were clearly indicated in better quality responses.

  2. Candidates were able to calculate the power dissipated by each lamp by using the current of 2 amps and the 12 Volt power supply to calculate the 24 watts.

  3. The majority of candidates correctly took the 24 watts for each lamp and calculated 72 watts. Some candidates who wrote poorer responses left the units of watts off the answer.

Question 20

    1. In better responses, candidates indicated that when the resistance was high both lamps would be dim and when resistance was low, at point B, both lamps would be bright. In poorer responses, candidates had either lamp as bright or dim, misunderstanding the flow of current in the circuit.

    2. Few candidates recognised that the voltage at the terminals of the lamp (L1) will be equal to the supply voltage when the lamp goes open circuit. The voltage will be available at the terminals. Many candidates answered that there would be zero volts across the terminals of lamp (L1) because it became open circuit. It was clear that too few candidates had done enough practical experimentation with circuits.

    3. Many candidates recognised that if the lamp (L1) goes open circuit, current will not flow and the total current will be zero.
  1. Most candidates did not apply the addition of series resistors to obtain a total resistance in the circuit of 5 kΩ or use V=IR to divide the 5 kΩ by the 24 V to obtain a total circuit current of 4.8 mA. This could then be used to calculate the voltage across R1 and R2, 4.8 V and 2.4 V respectively to then total 7.2 V. There were very few high-quality responses to this question. Candidates were rewarded for completing parts of this question. It is important that candidates attempt all questions, as there are many opportunities to gain marks.

Section III

Question 21

In better responses, candidates referred to OHS requirements, as stated in the question and recognised that the power tools would need to be tested and tagged and stored securely on site, that the 4-metre conduit would need a 2-person carry, conduit adhesive was a chemical and would require reference to material safety data sheet (MSDS) and chemical storage protocols, while the 300 metre roll of 16 mm2 cable would be very heavy and perhaps require a trolley or jack for moving. In better responses, candidates also included managing the public at the roadside, assuming that the truck was parked outside the site.

In poorer responses, candidates typically did not recognise the full range of varied OHS requirements in this delivery nor the implications of the large, long or heavy loads. In many of these responses, candidates did not refer to OHS matters at all, but described rather than explained a process of storage and manual handling. Many candidates suggested procedures that were dangerous practices and would result in injury.

Candidates need to apply safe and appropriate working practices in all cases and, when unsure of correct handling procedures, a more senior colleague should be consulted to avoid injury.

Section IV

Question 22

  1. Most candidates understood and addressed the use of personal protective equipment (PPE) relevant to the question and addressed both the storage and the handling of the chemical. Better responses also included reference to the MSDS, as the primary reference in the correct handling, storing and transporting of the chemical.

  2. There were a wide variety of responses to this question. In better responses, candidates addressed the tagging of and isolation of the fan prior to removal. These candidates typically talked about dismantling the fan for a thorough cleaning and understood the importance of liaising with the customer and the restaurant owner prior to the job being carried out. In better responses, candidates also understood that the cleaning of the fan in a food-preparation area had separate requirements they would need to consider.

    Better responses did include conducting an isolation resistance test. Most candidates included the importance of communication to the restaurant personnel and OHS issues, such as barricades, drop sheets, tools, ladders and safe working height. Better responses concluded with the completion of appropriate paper work, test report, job sheet, time sheets and invoicing.

    In poorer responses, candidates did not refer to the OHS issues or the proper isolation of the fan. Few candidates referred to isolating the area around the fan from workers rather than/or additional to the electrical isolation of the circuit and checking it and the test equipment prior to dismantling for a thorough clean.
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