©2024 TVET CDACC
071306T4EEN
ELECTRICAL TECHNICIAN (POWER OPTION) LEVEL 6
ENG/OS/PO/CR/03/6
INSTALL ELECTRICAL MACHINE
July/August 2024
Time: 3 Hours
TVET CURRICULUM DEVELOPMENT, ASSESSMENT AND CERTIFICATION
COUNCIL (TVET CDACC)
WRITTEN ASSESSMENT
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3 HOURS
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INSTRUCTIONS TO CANDIDATE:
1. This tool consists of TWO sections: A and B.
2. Answer ALL questions in sections A and only THREE in section B in the
answer booklet provided.
3. Marks for each question are indicated in brackets.
4. Do not write on this question paper.
5. Answer the questions in English.
This tool consists of FOUR (4) printed pages.
Candidate should check the question paper to ascertain that all the pages are printed as
indicated and that no questions are missing.
Page 1 of 4
©2024 TVET CDACC
SECTION A (40 MARKS)
Answer ALL the questions in this section.
1. D.C motor fails to start when switched on, troubleshooting the specific issue would involve a
closer examination of the motor and its surrounding components. State four possible reasons for
failure to start. (4 marks)
2. Laying underground cables involves burying electrical cables beneath the ground to transmit
electricity from one location to another List four disadvantages of direct laying. (4marks)
3. Electrical machines, such as motors and generators, can experience various types of cable faults
that can affect their performance, efficiency, and safety. Outline three types of cable fault.
(3 marks)
4. Improving efficiency in a generator involves optimizing various aspects of its design, operation,
and maintenance. State four factors that increases efficiency in the generator.
(4 marks)
5. The components of an electrical control panel can vary depending on its purpose and the specific
requirements of the system it's controlling. State four components of the control panel.
(4 marks)
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6. Testing and inspection of electrical machines are crucial for ensuring safety, performance, and
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reliability. Identify five types of tests. (5 marks)
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7. For three-phase electrical machines, particularly motors and generators, several types of cables
are commonly used to connect them to the power supply and control systems. Highlight three
types of cables used for 3-phase service in electrical machines. (3 marks)
8. When laying machine cables in accordance with IEE (Institution of Electrical Engineers)
regulations, several regulations must be followed to ensure safety, reliability, and compliance
with standards. State four IEE regulations on the cables. (4 marks)
9. Ensuring safety during the layout and installation of electrical DC motors is crucial to prevent
accidents, protect personnel, and maintain operational integrity. Outline five safety measures
during the motor layout installation. (5 marks)
10. Excessive sparking at the brushes in a DC motor can be indicative of various underlying issues
within the motor or its operating environment. List four causes of excessive sparking at the
brushes in a d.c motor. (4 marks)
Page 2 of 4
©2024 TVET CDACC
SECTION B (60 MARKS)
Answer any three questions in this section.
11.
a) Product layout, also known as line layout or assembly line layout, involves arranging
machinery and equipment in a sequence that follows the production process. Outline three
advantages and two disadvantages of product layout. (5 marks)
b) Transformers are electrical machines that transfer electrical energy between two or more
circuits through electromagnetic induction. Explain five types of transformers. (15 marks)
12.
a) Starting synchronous motors requires special techniques to overcome the inherent
characteristic of synchronous motors that they cannot self-start. Explain six methods of
starting synchronous motors. (12 marks)
b) Mounting an electrical machine involves the process of securely installing it in a designated
location or onto a suitable surface to ensure proper operation and safety. Explain four
procedures of mounting an electrical machine. (8 marks)
13.
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a) Nasimiyu is an electrical designer in a maize seed company who has been assigned a task to
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select cable size. Discuss five factors to be considered when selecting cable size. (10 marks)
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b) In the context of electrical machines, such as motors, generators, transformers, etc., testing
and inspection play crucial roles in ensuring their proper operation, safety, and longevity.
Explain the difference between testing and inspection in electrical machine installation.
(6 marks)
c) Preventive maintenance plays a crucial role in ensuring the longevity and efficiency of
motors. Outline four importance of preventive maintenance in motors. (4 marks)
Page 3 of 4
©2024 TVET CDACC
14.
a) In addition to product layout, there are three other common types of layouts used in
designing machines, explain three other layouts used in designing machines. (6 marks)
b) Cable termination in transformers involves a series of processes and tools to ensure safe and
efficient electrical connections. Describe three tools and equipment used in cable
termination in transformers. (6 marks)
c) A 3φ, 460 V, 100 hp, 60 Hz, four-pole induction machine delivers rated output power at a
slip of 0.05. Determine the:
i. Synchronous speed and motor speed;
ii. Speed of the rotating air gap field;
iii. Frequency of the rotor circuit. (8 marks)
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THIS IS THE LAST PRINTED PAGE
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