©2025 TVET CDACC

Printed By: Coast Institute Of Technology

Date: 28.03.2025 09:09 PM
071305T4EOP
ELECTRICAL OPERATION LEVEL 5
ENG/OS/PO/CR/03/5/A
Install Electrical Machine
March/April 2025

TVET CURRICULUM DEVELOPMENT, ASSESSMENT AND CERTIFICATION

COUNCIL (TVET CDACC)

WRITTEN ASSESSMENT
Printed By: Coast Institute Of Technology
Date: 28.03.2025 09:09 PM
Time: 3 HOURS

INSTRUCTIONS TO CANDIDATE

1. This paper consists of TWO sections: A and B.

2. Marks for each question are indicated in the brackets.
3. Candidates are provided with a separate answer booklet.
4. DO NOT write on this question paper.

This paper consists of FOUR (4) printed pages

Candidates should check the question paper to ascertain that all pages are printed as
indicated and that no questions are missing.
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Date: 28.03.2025 09:09 PM
 ©2025 TVET CDACC
Printed By: Coast Institute Of Technology
Date: 28.03.2025 09:09 PM
SECTION A (40 MARKS)
Answer ALL the questions in this section.
1. Motor starting methods are techniques used to initiate the operation of electric motors smoothly
and efficiently. State FOUR motor starting methods. (4 Marks)
2. Electrical machines are devices that convert mechanical energy to electrical and vice versa for
various functions depending on their performance. Enumerate any THREE classification of
electrical machines. (3 Marks)
3. List any TWO essential parts of an electro-mechanical system. (2 Marks)
4. Earthing is process of connecting an electrical system to the general earth mass for disposal of
excess current. State THREE importance of earthing in electrical machines. (3 Marks)
5. Safety is a crucial aspect that is required when mounting electrical machines. State any FOUR
safety requirements during mounting of electrical machines. (4 Marks)
6. Cable termination is the physical and electrical connection of a cable end that connects to
another cable or terminal of machine. List THREE types of terminations. (3 Marks)
7. Testing and inspection is the procedure used to check and ensure that circuit is working
correctly and safe before being energized for an electrical machine. State FOUR importance of
testing electrical machine installations.Printed By: Coast Institute Of Technology (4 Marks)
Date: 28.03.2025 09:09 PM
8. Electrical machines must undergo scheduled repair and maintenance. List FOUR steps of fault
finding in electrical components and equipment. (4 Marks)
9. State THREE types of DC compound motors. (3 Marks)
10. Enumerate any FOUR electrical tests done in a transformer before installation. (4 Marks)
11. List THREE basic parts of DC machines. (3 Marks)
12. State THREE generator starting systems. (3 Marks)

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Date: 28.03.2025 09:09 PM
 ©2025 TVET CDACC
Printed By: Coast Institute Of Technology
Date: 28.03.2025 09:09 PM
SECTION B (60 MARKS)
Answer any THREE questions in this section
13. (a) A 6-pole lap wound motor is connected to a 250V DC supply. The armature has 500
conductors and resistance of 1Ω. The flux per pole is 20mWb. Calculate the following;
(i) The motor speed; (5 Marks)
(ii) The torque developed when the armature current is 40A. (3 Marks)
(b) Transformer losses can significantly impact their efficiency and overall performance.
Explain any THREE types of losses in a transformer. (6 Marks)
(c) It is important to perform cable segregation when laying cables for the electrical machines
installation. Discuss any THREE importance of cable segregation. (6 Marks)
14. (a) A DC motor converts DC electrical energy to mechanical energy using the principles of
electromagnetism. Describe the construction and operation of DC motors. (6 Marks)
(b) A 415 V, three phase, 50Hz four-pole, star connected induction motor runs at 24 rev/s on
full load. The rotor resistance and reactance per phase are 0.35Ω and 3.5Ω respectively, and
the effective rotor-stator turn ratio is 0.85:1. Calculate:
(i) The synchronous speed; (2 Marks)
(ii) The slip; Printed By: Coast Institute Of Technology (2 Marks)
Date: 28.03.2025 09:09 PM
(iii) The full load torque; (3 Marks)
(iv) The power output if mechanical losses amount to 770W; (2 Marks)
(v) The maximum torque; (3 Marks)
(vi) The starting torque. (2 Marks)
15. (a) A 3-phase Y-connected synchronous generator supplies a load of 10MW at power factor
0.85 lagging and the terminal voltage is 11kV. The armature resistance is 0.1 ohm/phase
and synchronous reactance is 0.66 ohm/phase. Calculate:
(i) Armature current; (4 Marks)
(ii) Internal generated voltage; (3 Marks)
(iii)Voltage regulation; (3 Marks)
(iv) Draw the phasor diagram. (2 Marks)
(b) Discuss any FOUR classifications of cables used in control panel installation.
(8 Marks)
16. (a) Electrical control panels are the integral part of any automated system that houses
various electronic devices that provide signals to direct the operation of electrical machines.
Discuss FIVE components of a control panel. (10 Marks)
(b) Explain the steps followed when conducting tests on a generator. (10 Marks)
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Date: 28.03.2025 09:09 PM