Final Exam Machine 2010
SULIT
UNIVERSITI TEKNOLOGI MALAYSIA PEPERIKSAAN AKHIR SEMESTER 1 SESI 2010/2011 KOD MATAPELAJARAN MATA PELAJARAN PENSYARAH : : : SEE 3433 MESIN ELEKTRIK DR. AWANG JUSOH EN. NIK DIN MUHAMAD DR. NIK RUMZI NIK IDRIS
KURSUS SEKSYEN MASA TARIKH
: : : :
SEE KL, P. PINANG, JB 2 JAM 30 MINIT
ARAHAN KEPADA CALON
:
JAWAB EMPAT (4) SOALAN SAHAJA. SEMUA PENGIRAAN HENDAKLAH DITUNJUKKAN DENGAN JELAS.
KERTAS SOALAN INI TERDIRI DARIPADA 6 (ENAM) MUKA SURAT SAHAJA
SEE 3433 -2Question 1
(a)
With the help of a simple electromechanical system, explain briefly how energy conversion process occurs in the system. Assume the system is lossless. [6 marks]
(b)
In the electromagnetic relay system, the flux linkage (λ) and current (i) relationship is given by: i = λ3 + 3λ(1- x)2 ; valid for 0 < x < 20cm Find the expression of the force acting on the moving part as a function of λ when x = 3cm. [6 marks]
(c)
An elementary two-pole cylindrical rotating machine with a uniform air gap is shown in Figure Q1(c). The mutual inductance between the rotor and the stator is given by Lsr = 0.5 cos θ Henries
The windings are supplied with either of two sources: Source A: Source B: 3 A DC 6 A r.m.s f = 50 Hz
The rotor is locked at θ = 50°. What is the torque developed for the following source connections: (i) (ii) Source A to both windings Source A to the rotor and source B to the stator.
Rotor axis
[6 marks] [7 marks]
θ = 50° (locked)
Stator axis
Figure Q1(c)
SEE 3433 -3Question 2 (a) Briefly explain what do you understand by an armature reaction in a DC machine. What effect does the armature reaction has on: (i) (ii) the flux per pole? generated back emf (Ea)?
(iii) commutation action?
Give two methods to reduce the effects of armature reaction [6 marks]
(b) A DC machine is to have the following rating: 240V, 1500 rpm, 4 poles. Coils to be used to construct the winding of the machine are rated at 5 V and 6 A. If the lap wind is
UNIVERSITI TEKNOLOGI MALAYSIA PEPERIKSAAN AKHIR SEMESTER 1 SESI 2010/2011 KOD MATAPELAJARAN MATA PELAJARAN PENSYARAH : : : SEE 3433 MESIN ELEKTRIK DR. AWANG JUSOH EN. NIK DIN MUHAMAD DR. NIK RUMZI NIK IDRIS
KURSUS SEKSYEN MASA TARIKH
: : : :
SEE KL, P. PINANG, JB 2 JAM 30 MINIT
ARAHAN KEPADA CALON
:
JAWAB EMPAT (4) SOALAN SAHAJA. SEMUA PENGIRAAN HENDAKLAH DITUNJUKKAN DENGAN JELAS.
KERTAS SOALAN INI TERDIRI DARIPADA 6 (ENAM) MUKA SURAT SAHAJA
SEE 3433 -2Question 1
(a)
With the help of a simple electromechanical system, explain briefly how energy conversion process occurs in the system. Assume the system is lossless. [6 marks]
(b)
In the electromagnetic relay system, the flux linkage (λ) and current (i) relationship is given by: i = λ3 + 3λ(1- x)2 ; valid for 0 < x < 20cm Find the expression of the force acting on the moving part as a function of λ when x = 3cm. [6 marks]
(c)
An elementary two-pole cylindrical rotating machine with a uniform air gap is shown in Figure Q1(c). The mutual inductance between the rotor and the stator is given by Lsr = 0.5 cos θ Henries
The windings are supplied with either of two sources: Source A: Source B: 3 A DC 6 A r.m.s f = 50 Hz
The rotor is locked at θ = 50°. What is the torque developed for the following source connections: (i) (ii) Source A to both windings Source A to the rotor and source B to the stator.
Rotor axis
[6 marks] [7 marks]
θ = 50° (locked)
Stator axis
Figure Q1(c)
SEE 3433 -3Question 2 (a) Briefly explain what do you understand by an armature reaction in a DC machine. What effect does the armature reaction has on: (i) (ii) the flux per pole? generated back emf (Ea)?
(iii) commutation action?
Give two methods to reduce the effects of armature reaction [6 marks]
(b) A DC machine is to have the following rating: 240V, 1500 rpm, 4 poles. Coils to be used to construct the winding of the machine are rated at 5 V and 6 A. If the lap wind is