Homework Answers
A)
| ASPECT OF DIFFERENCE | SYNCHRONOUS MOTORS | INDUCTION MOTORS |
| EXCITATION | Doubly Excited ( AC on stator + DC on the Rotor ) | Singly Excited ( Only AC on Stator) |
| SPEED |
Synchronous Speed ( So Constant Speed only ) Also Speed is load Independent |
Slip Speed ( So can have Variable Speeds) Speed is Load Dependent |
| STARTING AID NEED | Need Starting Aid ( like Pony or Dummy motors , Damper Windings) | Self Startng Motor |
| EFFICIENCY | High | Comparitively Low |
| POWER FACTOR RANGE | Wide Range ( From Lead To Lag ) | Only Lag Power Factor |
B)
C)
DC machines are selected as per various factors Like
a)Types of Drive they will Operate
The Series motor Are Suitable For Constant Power Drives
The Shunt motor Are Suitable For Constant Speed Drives
b) As per Resistance of Armature and Field
This is significant in machines when our concern is to Limit The Copper Losses
c) As per Voltage Regulation Need
In DC Generators where we may need Various Regulation as per Electrical Load connected and our needs
d) As per Power Rating Need For Corresponding Usage
APPLICATIONS :
Series DC Machine : Traction motors , Conveyors As Motors
Negative Voltage Regulation As Generators
Shunt DC Machine : Machine Tools and Lathe , Shearing , Pumps As Motors
Positive Voltage Regulation As Generators
Compound DC Machine : Lifts , Rolling Mills And Pressing
Induction Motor : Electric Cars , Traction
Synchronous Motor : As Phase Correction Device , Trains , Escalators
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Q5(a) Differentiate between Induction and Synchronous motors. (5 marks) A generator shown in Figu...
need full solution plz A figure in the following shows a connection between a synchronous generator and a synchronou...
need full solution plz
A figure in the following shows a connection between a synchronous generator and a synchronous motor. The rated specifications of each of the two machines are also shown. Pout(G)Pin(M) Synchronous Pin(G) Synchronous Pout(M) C. Generator Motor Sync. Generator Specifications Sync. Motor Specifications Terminal Voltage 480 V | Terminal Voltage Power Factor 0.8 lagging Power Factor 0.8 leading Apparent Power 200-kVA Active Power 40-kW Frequency 50 Hz Frequency Y (wye) Connection 0.30Synch Reactance 0.0 Ω I Armature...
6) 480 V, 0.5 KHz. A -connected. P-pole synchronous generator. This generator has a synchronous reactance...
6) 480 V, 0.5 KHz. A -connected. P-pole synchronous generator. This generator has a synchronous reactance of 0.11 and an armature resistance of 0.015 N. IL = 1310- At full load, the machine supplies 1200 A at 0.8 PF lagging. The phasor diagram of the generator is shown below. E RU 1. = 692.82 -36.87°A Figure 2 i. 11. Calculate the number of poles (P) if the speed of rotation of this generator ise 3000 r/min? [2 marks] If the...
a. The figure below is a set of Synchronous Generator and Synchronous Motor. The ratings of...
a. The figure below is a set of Synchronous Generator and Synchronous Motor. The ratings of the machines are as follows: Synchronous Generator:. 3ph, 1.0MVA, 2.3kV, 50Hz, 0.85 lagging power factor, X.=0.9 pu Synchronous Motor: 3ph, 0.5 MVA, 2.36V, 50Hz, 0.85 leading power factor, X.=0.8 pu Synchronous generator Synchronous motor The generator is equipped with a voltage regulator which maintains the terminal voltage at the rated value. The motor delivers 500 hp and it field current is adjusted to make...
Question 4 (10 marks) A) A 10-kVA, 415-V, three phase, Y -connected synchronous generator has a...
Question 4 (10 marks) A) A 10-kVA, 415-V, three phase, Y -connected synchronous generator has a winding resistance of 0.3 Q and a synchronous reactance of 0.6 on a per phase basis. Determine its voltage regulation at full load when the power factor is (a) 75% lagging and (b) 75% leading. B) (10 marks) A 220-V, Y-connected, three-phase, synchronous motor has a synchronous reactance of 4 O/phase and negligible armature winding resistance. At a certain load the motor takes 7.5...
[12 marks] 2.(30 marks] a) Description of Core Loss in synchronous generator. When does the loss ...
[12 marks] 2.(30 marks] a) Description of Core Loss in synchronous generator. When does the loss occur? [6 marks] b) A 3 phase, 2 poles, 4.16 kV, wye-connected synchronous generator with 50 Hz is applied as an emergency power source to supply 500 kW at a power factor of 0.9 lagging. The stator resistance is 0.3 Q/phase. Rotational losses in the machine are estimated to be 15 kW. Determine the required horsepower and torque of the prime mover. [12 marks]...
A 480-V, 60-Hz, A-connected, four-pole synchronous generator has a synchronous reactance of 0.1 ohm and an...
A 480-V, 60-Hz, A-connected, four-pole synchronous generator has a synchronous reactance of 0.1 ohm and an armature resistance of 0.0 15 ohm. At full load, the machine supplies 1200 A at 0.8 PF lagging. Under full-load conditions, the friction and windage losses are 40 kW, and the core losses are 30 kW. Ignore any field circuit losses c) How much power is the generator now supplying? How much power is supplied to the generator by the prime mover? What is...
Problem 1: Synchronous Machine Generator and Motor Operation A 10 MVA, 2300 Volt (Line to line...
Problem 1: Synchronous Machine Generator and Motor Operation A 10 MVA, 2300 Volt (Line to line xms) uniform airgap synchronous machine has a synchronous reactance of 0.9 pu at 60 Hz and resistance may be neglected. The machine is connected to a 2300 Volt constant voltage, constant frequency source and operated as described below (a) Generator Operation - Find the power, reactive power, current, and the required internal voltage E for generator operation at rated volt-amperes and power factors of...
Three physically identical synchronous generators are operating in parallel. They are all rated for a full...
Three physically identical synchronous generators are operating in parallel. They are all rated for a full load of 3 MW at 0.8 PF lagging. The no-load frequency of generator A is 61.2 Hz, and its speed droop is 3.4 percent. The no-load frequency of generator B is 61.5 Hz, and its speed droop is 3 percent. The no- load frequency of generator C is 60.5 Hz, and its speed droop is 2.6 percent. (a) If a total load consisting of...
2) A 480 V, 60 Hz, 400 hp 0.8 PF-lagging eight-pole A-connected synchronous motor has a...
2) A 480 V, 60 Hz, 400 hp 0.8 PF-lagging eight-pole A-connected synchronous motor has a synchronous reactance of 0.6 and negligible armature resistance. Ignore the mechanical and core losses. The magnitude of the internal machine voltage is 480 V when the field current is 4 A. Assume magnetic linearity. Initially, the motor operates at the rated conditions. a) Find the speed of this motor. b) Find the armature and field currents. c) What is the developed torque? What is...
A 480-V, 50-Hz, Y-connected, 6-pole synchronous generator has a synchronous reactance of 1 Ohm. Its full...
A 480-V, 50-Hz, Y-connected, 6-pole synchronous generator has a synchronous reactance of 1 Ohm. Its full load armature current is 60 A at 0.8 pf lagging. Under full load conditions, the friction and windage losses are 1.5 kW, and core losses are 1 kW at 50 Hz. Ignore armature copper losses. The field has been adjusted so that the terminal voltage is 480 V at no load. a.What is the speed of rotation of this gen? b.What is the generator...
need full solution plz
A figure in the following shows a connection between a synchronous generator and a synchronous motor. The rated specifications of each of the two machines are also shown. Pout(G)Pin(M) Synchronous Pin(G) Synchronous Pout(M) C. Generator Motor Sync. Generator Specifications Sync. Motor Specifications Terminal Voltage 480 V | Terminal Voltage Power Factor 0.8 lagging Power Factor 0.8 leading Apparent Power 200-kVA Active Power 40-kW Frequency 50 Hz Frequency Y (wye) Connection 0.30Synch Reactance 0.0 Ω I Armature...
6) 480 V, 0.5 KHz. A -connected. P-pole synchronous generator. This generator has a synchronous reactance of 0.11 and an armature resistance of 0.015 N. IL = 1310- At full load, the machine supplies 1200 A at 0.8 PF lagging. The phasor diagram of the generator is shown below. E RU 1. = 692.82 -36.87°A Figure 2 i. 11. Calculate the number of poles (P) if the speed of rotation of this generator ise 3000 r/min? [2 marks] If the...
a. The figure below is a set of Synchronous Generator and Synchronous Motor. The ratings of the machines are as follows: Synchronous Generator:. 3ph, 1.0MVA, 2.3kV, 50Hz, 0.85 lagging power factor, X.=0.9 pu Synchronous Motor: 3ph, 0.5 MVA, 2.36V, 50Hz, 0.85 leading power factor, X.=0.8 pu Synchronous generator Synchronous motor The generator is equipped with a voltage regulator which maintains the terminal voltage at the rated value. The motor delivers 500 hp and it field current is adjusted to make...
Question 4 (10 marks) A) A 10-kVA, 415-V, three phase, Y -connected synchronous generator has a winding resistance of 0.3 Q and a synchronous reactance of 0.6 on a per phase basis. Determine its voltage regulation at full load when the power factor is (a) 75% lagging and (b) 75% leading. B) (10 marks) A 220-V, Y-connected, three-phase, synchronous motor has a synchronous reactance of 4 O/phase and negligible armature winding resistance. At a certain load the motor takes 7.5...
[12 marks] 2.(30 marks] a) Description of Core Loss in synchronous generator. When does the loss occur? [6 marks] b) A 3 phase, 2 poles, 4.16 kV, wye-connected synchronous generator with 50 Hz is applied as an emergency power source to supply 500 kW at a power factor of 0.9 lagging. The stator resistance is 0.3 Q/phase. Rotational losses in the machine are estimated to be 15 kW. Determine the required horsepower and torque of the prime mover. [12 marks]...
Problem 1: Synchronous Machine Generator and Motor Operation A 10 MVA, 2300 Volt (Line to line xms) uniform airgap synchronous machine has a synchronous reactance of 0.9 pu at 60 Hz and resistance may be neglected. The machine is connected to a 2300 Volt constant voltage, constant frequency source and operated as described below (a) Generator Operation - Find the power, reactive power, current, and the required internal voltage E for generator operation at rated volt-amperes and power factors of...
Three physically identical synchronous generators are operating in parallel. They are all rated for a full load of 3 MW at 0.8 PF lagging. The no-load frequency of generator A is 61.2 Hz, and its speed droop is 3.4 percent. The no-load frequency of generator B is 61.5 Hz, and its speed droop is 3 percent. The no- load frequency of generator C is 60.5 Hz, and its speed droop is 2.6 percent. (a) If a total load consisting of...
2) A 480 V, 60 Hz, 400 hp 0.8 PF-lagging eight-pole A-connected synchronous motor has a synchronous reactance of 0.6 and negligible armature resistance. Ignore the mechanical and core losses. The magnitude of the internal machine voltage is 480 V when the field current is 4 A. Assume magnetic linearity. Initially, the motor operates at the rated conditions. a) Find the speed of this motor. b) Find the armature and field currents. c) What is the developed torque? What is...
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