Category: EK ELECTRICS

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(a) Sketch a cross section through an a.c. induction motor. (5) (b) Describe the construction of the a.c. induction motor sketched in part (a). (5) Mar 2024 (Q10)

EK Electrical Mar 2024 (Q9)

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(a) Explain the term power factor. (2) (b) Explain why it is detrimental to have a low power factor. (2) (c) Explain, with the aid of phasor diagrams, how a synchronous motor may be used to assist in power factor correction (6) Mar 2024 (Q9)

EK Electrical Dec 2023 (Q11)

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With reference to the protection of electrical power circuits: (a) Explain discrimination, describing how it is achieved (5) (b) State, with reasons, the type of fuses used for protection (3) (c) Explain preferential tripping (2) Dec 2023 (Q11)

EK Electrical Dec 2023 (Q10)

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With reference to braking of a.c. induction motors: (a) Explain why braking may be required (2) (b) Explain why electrical braking is preferable to mechanical braking (2) (c) Explain the term plugging (2) (d) Describe how dynamic braking is achieved (4) Dec 2023 (Q10)

EK Electrical Dec 2023 (Q9)

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(a) Sketch a circuit showing how the emergency generator is started, connected to the emergency busbars and how the main busbars are disconnected in the event of a blackout. (6) (b) Explain how an emergency generator can be tested to ensure that it is capable of satisfactorily delivering the rated power. (4) Dec 2023 (Q9)

EK Electrical Oct 2023 (Q11)

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With reference to large electrical transformers on board ships (a) State where these transformers may be used (1) (b) State a typical efficiency range for a transformer (1) (c) State the regulations pertaining to transformers (3) (d) State the protective devices that are fitted (2) (e) Describe the maintenance requirements (3) Oct 2023 (Q11)

EK Electrical Oct 2023 (Q10)

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With reference to voltage variation profiles caused by load changes imposed on alternating current generators when starting large motors on line: (a) Sketch a voltage dip, showing an acceptable recovery time (2) (b) State FOUR salient factors that cause the variation in part (a) (4) (c) Outline FOUR salient factors that assist recovery from the…

EK Electrical Oct 2023 (Q9)

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With reference to reverse power protection for a.c generator operating in parallel (a) Explain why traditional reverse power relays, operating on mechanical principles, have been replaced by electronic digital microprocessor types (2) (b) Describe, with the aid of a sketch, a generator reverse power protection circuit that uses an electronic phase sensitive detector (8) Oct…

EK Electrical Jul 2023 (Q11)

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With reference to testing High Voltage equipment: (a) Explain why earthing down is considered essential (2) (b) State the operating voltage for an insulation resistance tester (megger) suitable for 6.6KV equipment (1) (c) Describe how an insulation resistance test is carried out on High Voltage equipment making reference to personnel safety (5) (d) Explain why…

EK Electrical Jul 2023 (Q10)

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