University of KwaZulu-Natal
School of Electrical, Electronic and Computer Engineering
Examinations: November 2018
Subject, Course & Code: ELECTRICAL MACHINES 2 – ENEL3MBH2
DURATION: 2 HOURS TOTAL MARKS: 100
Examiners: Dr. R. Pillay Carpanen (Internal)
Dr. R. Tiako (Moderator)
Instructions: Answer ALL Questions. Start answering each
question on a fresh page of the answer booklet.
The use of scientific calculators is permitted but
their memories must be cleared.
QUESTION 1 [46 Marks]
A test taken on a star-connected 55 kVA, 50 Hz, 6-pole synchronous generator
yields the following results:
1. Open-circuit terminal line voltage is 400 V for a dc exciting current of 15 A
2. Using the same dc current, with the armature short-circuited the resulting ac
line current is 171 A.
Calculate the following:
(a) the base impedance of the generator, per phase. [3]
(b) the value of the synchronous reactance. [1]
(c) the per-unit value of XS. [1]
(d) the short-circuit ratio. [1]
Page 1 of 4
School of Electrical, Electronic and Computer Engineering
Examinations: November 2018
Subject, Course & Code: ELECTRICAL MACHINES 2 – ENEL3MBH2
DURATION: 2 HOURS TOTAL MARKS: 100
Examiners: Dr. R. Pillay Carpanen (Internal)
Dr. R. Tiako (Moderator)
Instructions: Answer ALL Questions. Start answering each
question on a fresh page of the answer booklet.
The use of scientific calculators is permitted but
their memories must be cleared.
QUESTION 1 [46 Marks]
A test taken on a star-connected 55 kVA, 50 Hz, 6-pole synchronous generator
yields the following results:
1. Open-circuit terminal line voltage is 400 V for a dc exciting current of 15 A
2. Using the same dc current, with the armature short-circuited the resulting ac
line current is 171 A.
Calculate the following:
(a) the base impedance of the generator, per phase. [3]
(b) the value of the synchronous reactance. [1]
(c) the per-unit value of XS. [1]
(d) the short-circuit ratio. [1]
Page 1 of 4
