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10. A primitive de machine has a field winding of resistance 20052 and inductance 40H. The...
3. A 25-kW, 230-V shunt motor has an armature resistance of 0.064 Ω and a field-circuit...
3. A 25-kW, 230-V shunt motor has an armature resistance of 0.064 Ω and a field-circuit resistance of 95 Ω. The motor delivers rated output power at rated voltage when its armature current is 122 A. When the motor is operating at rated voltage, the speed is observed to be 1150 r/min when the machine is loaded such that the armature current is 69.5 A a. Calculate the rated-load speed of this motor In order to protect both the motor...
A 8250 w shunt DC motor has a terminal voltage of 300 V. A field resistance...
A 8250 w shunt DC motor has a terminal voltage of 300 V. A field resistance Rf of 40 Ω, and an armature resistance Ra of 250 mm2. The field winding has 1500 turns. An adjustable resistance Rad is connected in series to the field winding. Rad is set at 20 Ω, but it can vary from 0 to 80 Ω. The magnetization curve is shown in Figure.1 and it is taken at a speed of 1200 rpm. (Armature reaction...
1. Name the various parts of a DC machine and give their function. 2. A four-pole...
1. Name the various parts of a DC machine and give their function. 2. A four-pole de machine with a lap wound armature has a total of 652 armature conductors with an armature resistance of 0.1502. When run as a generator on open circuit at a speed of 400rpm, the armature terminal voltage is 262V. Each pole shoe arc has a diameter of 42cm, subtends an angle of 60° and has an axial length of 20cm. 2.1.Calculate the useful flux...
Consider a three-phase, 2-pole induction machine. Neglect the stator winding resistance and the leakage inductance. The...
Consider a three-phase, 2-pole induction machine. Neglect the stator winding resistance and the leakage inductance. The rated voltage is 217V (line-line, rms) at 60 Hz. Lm65mH, and the peak flux density in the air gap is 0.89T. Consider that the phase-a voltage reaches its positive peak at wt-0. Assuming that the rotor circuit is somehow open circuited, calculate the position(angle) of the magnetizing current space vector ims at wt-4g°.
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...
Problem 1: A four pole, 60Hz, 3-d synchronous generator has a rotor radius of 15 cm, a rotor length of 2.7m, and an air gap length of 2 mm. The rotor field winding consists of 1000 turns with a wi...
Problem 1: A four pole, 60Hz, 3-d synchronous generator has a rotor radius of 15 cm, a rotor length of 2.7m, and an air gap length of 2 mm. The rotor field winding consists of 1000 turns with a winding factor of 0.962. The Δ connected armature winding has 25 series turns per phase with a winding factor of 0.935. The generator is designed to achieve rated open-circuit voltage at a peak air-gap flux density of 1.25 T (a) At...
T u resistance in a DC is decreased while the motor is driving a ii. A...
T u resistance in a DC is decreased while the motor is driving a ii. A 100-hp, 250-V DC shunt motor with compensating winding has an am 0.04 12 and a variable shunt field resistance R; 92. The magn ompensating winding has an armature resistance of shunt field resistance R, 12. The magnetization curve of this motor is shown in Fig. 1. At no load, the field resistor has been a . At no load, the field resistor has been...
A shunt de motor is rated at 6kW, 120V and 1200 r/min has a magnetization curve...
A shunt de motor is rated at 6kW, 120V and 1200 r/min has a magnetization curve as shown in Figure 1. The armature resistance is 0.189 and the field resistance is 2002 with and adjustable field resistance of 0 to 4002. The shunt de motor has rated line current of 50A when supplying rated voltage. (a) Determine the value of the adjustable field resistance so that the motor operates at no- load speed of 1200 r/min. [5 marks] (b) Assuming...
(11%) Problem 2: The winding of an AC electric motor has an inductance of 29 mH...
(11%) Problem 2: The winding of an AC electric motor has an inductance of 29 mH and a resistance of 19 2. The motor runs on a 60-Hz rms voltage of 120 V. 33% Part (a) What is the rms current that the motor draws, in amperes? Ims = 5.61 ✓ Correct! * 33% Part (b) By what angle, in degrees, does the current lag the input voltage? 33% Part (c) What is the capacitance, in microfarads, of the capacitor...
A 30 hp, 240 V, 1150 rpm de shunt motor operating at rated conditions has an efficiency of 88.5%. The armature circuit resistance and field circuit resistance are 0.096 Ω and 936 Ω respectively. Calc...
A 30 hp, 240 V, 1150 rpm de shunt motor operating at rated conditions has an efficiency of 88.5%. The armature circuit resistance and field circuit resistance are 0.096 Ω and 936 Ω respectively. Calculate the following: (a) the armature current; b) the output torque (c) the mechanical developed power (d) the mechanical developed torque; and, e) the external resistance required in series with the armature to limit the starting torque to 200 % of rated torque. If the load...
3. A 25-kW, 230-V shunt motor has an armature resistance of 0.064 Ω and a field-circuit resistance of 95 Ω. The motor delivers rated output power at rated voltage when its armature current is 122 A. When the motor is operating at rated voltage, the speed is observed to be 1150 r/min when the machine is loaded such that the armature current is 69.5 A a. Calculate the rated-load speed of this motor In order to protect both the motor...
A 8250 w shunt DC motor has a terminal voltage of 300 V. A field resistance Rf of 40 Ω, and an armature resistance Ra of 250 mm2. The field winding has 1500 turns. An adjustable resistance Rad is connected in series to the field winding. Rad is set at 20 Ω, but it can vary from 0 to 80 Ω. The magnetization curve is shown in Figure.1 and it is taken at a speed of 1200 rpm. (Armature reaction...
1. Name the various parts of a DC machine and give their function. 2. A four-pole de machine with a lap wound armature has a total of 652 armature conductors with an armature resistance of 0.1502. When run as a generator on open circuit at a speed of 400rpm, the armature terminal voltage is 262V. Each pole shoe arc has a diameter of 42cm, subtends an angle of 60° and has an axial length of 20cm. 2.1.Calculate the useful flux...
Consider a three-phase, 2-pole induction machine. Neglect the stator winding resistance and the leakage inductance. The rated voltage is 217V (line-line, rms) at 60 Hz. Lm65mH, and the peak flux density in the air gap is 0.89T. Consider that the phase-a voltage reaches its positive peak at wt-0. Assuming that the rotor circuit is somehow open circuited, calculate the position(angle) of the magnetizing current space vector ims at wt-4g°.
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...
Problem 1: A four pole, 60Hz, 3-d synchronous generator has a rotor radius of 15 cm, a rotor length of 2.7m, and an air gap length of 2 mm. The rotor field winding consists of 1000 turns with a winding factor of 0.962. The Δ connected armature winding has 25 series turns per phase with a winding factor of 0.935. The generator is designed to achieve rated open-circuit voltage at a peak air-gap flux density of 1.25 T (a) At...
T u resistance in a DC is decreased while the motor is driving a ii. A 100-hp, 250-V DC shunt motor with compensating winding has an am 0.04 12 and a variable shunt field resistance R; 92. The magn ompensating winding has an armature resistance of shunt field resistance R, 12. The magnetization curve of this motor is shown in Fig. 1. At no load, the field resistor has been a . At no load, the field resistor has been...
A shunt de motor is rated at 6kW, 120V and 1200 r/min has a magnetization curve as shown in Figure 1. The armature resistance is 0.189 and the field resistance is 2002 with and adjustable field resistance of 0 to 4002. The shunt de motor has rated line current of 50A when supplying rated voltage. (a) Determine the value of the adjustable field resistance so that the motor operates at no- load speed of 1200 r/min. [5 marks] (b) Assuming...
(11%) Problem 2: The winding of an AC electric motor has an inductance of 29 mH and a resistance of 19 2. The motor runs on a 60-Hz rms voltage of 120 V. 33% Part (a) What is the rms current that the motor draws, in amperes? Ims = 5.61 ✓ Correct! * 33% Part (b) By what angle, in degrees, does the current lag the input voltage? 33% Part (c) What is the capacitance, in microfarads, of the capacitor...
A 30 hp, 240 V, 1150 rpm de shunt motor operating at rated conditions has an efficiency of 88.5%. The armature circuit resistance and field circuit resistance are 0.096 Ω and 936 Ω respectively. Calculate the following: (a) the armature current; b) the output torque (c) the mechanical developed power (d) the mechanical developed torque; and, e) the external resistance required in series with the armature to limit the starting torque to 200 % of rated torque. If the load...
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