5. Explain the condition for a DC motor to develop the maximum power. If a DC...
5. Explain the condition for a DC motor to develop the maximum power. If a DC machine having an armature resistance of 0.5Ω and the full load current of 20 A. Find the induced emf of machine when it acts as: (i) Motor and (ii) Generator
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5. Explain the condition for a DC motor to develop the
maximum power. If a DC...
A 250V DC shunt machine has an armature resistance of 0.5Ω and shunt field resistance of...
A 250V DC shunt machine has an armature resistance of 0.5Ω and shunt field resistance of 125Ω, when it is running as a motor, the current taken from the supply is 5A. Calculate the efficiency of the machine i) On no- load ii) As a motor when taking a current of 52A from the supply iii) As a generator when delivering a current of 35A. b) Distinguish between induction motor and synchronous motor.
1. A 300 V compound motor has armature resistance 0.18 Ω, series field resistance 0.3 Ω...
1. A 300 V compound motor has armature resistance 0.18 Ω, series field resistance 0.3 Ω and shunt field resistance 100 Ω. The rotational losses are 200 W. On full load the line current is 25 A and the motor runs at 1800 rpm. Determine: (i) the developed mechanical power (ii) the output power (iii) the output torque (iv) the efficiency at full load 2. A 120 V series motor has 0.2 Ω field resistance. On full load, the line...
A 6 hp, 180 V shunt dc motor draws a full-load current of 30 A from the power supply. The motor h...
A 6 hp, 180 V shunt dc motor draws a full-load current of 30 A from the power supply. The motor has a field (shunt) resistance of 150 Ω. The armature resistance of the motor is 0.1 Ω. When the motor speed is 1800 rpm (this is not the full-load speed), the relationship between the induced voltage
Q1b) DC Machines [ 6 marks ] You are given a 24 V DC motor. When...
Q1b) DC Machines [ 6 marks ] You are given a 24 V DC motor. When you connect it to a 24 V supply, under no-load conditions it spins at 2,000 rpm. With the same 24 V supply, when the motor is stalled, the input current is 50 A. i) Calculate the back-emf constant and hence the stall torque of the motor. Find also the armature resistance. [3 marks ] ii) The DC motor has a rated input current of...
3. A 20kW, 250V, 1000rpm shunt excited dc motor has armature and field resistances of 0.2...
3. A 20kW, 250V, 1000rpm shunt excited dc motor has armature and field resistances of 0.2 ohm and 2002. When the motor takes 80A rated current at rated conditions. Draw the equivalent circuit and calculate induced torque at 1200rpm. Explain the starting current limiting methods for DC motors. (30 pts) 4. Explain the conditions for parallel operation of synchronous generators. A three phase, wye connected, synchronous generator is rated 150 MW, 0.85 lagging power factor, 12.6 kV, 60 Hz, and...
Problem 3: DC machine A shunt DC motor rated at V,'. 300 V, with field resistance...
Problem 3: DC machine A shunt DC motor rated at V,'. 300 V, with field resistance of Rf 600 0, armature 0.2 , resistance of R, 30.5 A (total current) when rated-load at n, consumes 916.8 rpm. Armature rotational loss (consisting of fan, friction and core loss (consisting of field resistance, armature a) Find Prot (rotational load), Pshaft and efficiency at rated load. - Assume that the rotational loss is constant and P,aft is now 50% in the case of...
The armature windings of a dc motor have a resistance of 8.0 Ω . The motor...
The armature windings of a dc motor have a resistance of 8.0 Ω . The motor is connected to a 120-V line, and when the motor reaches full speed against its normal load, the back emf is 108 V. The load is increased so it causes the motor to run at half speed. What will be the current in the motor in this case? (Express your answer to two significant figures and include the appropriate units.)
3) The armature of a permanent-magnet dc motor has a resistance of 0.72 and draws a...
3) The armature of a permanent-magnet dc motor has a resistance of 0.72 and draws a current of 50 A when the speed is 1500 r/min when the armature is connected to a source of 48 V, calculate the following: a) The induced emf, EA, and the torque, T, produced at this speed. b) The motor speed, n (in rpm), when the torque is 2 Nm. c) The armature current at 1600 r/min. d) The torque at 1600 r/min. e)...
b) A 1MW, 3300 V, 50 Hz, wye-connected, 3-ф, twenty four-pole, synchronous motor has a synchronous...
b) A 1MW, 3300 V, 50 Hz, wye-connected, 3-ф, twenty four-pole, synchronous motor has a synchronous reactance of 3.24 2 per phase. Assume armature resistance is negligible. This machine is connected to an infinite bus-bars at 3300 V. Its field excitation is adjusted to provide P.F-1 at rated load Calculate: 0 the internal generated voltage EA and armature current la at rated conditions (S marks) ii) the maximum power and torqu e that the motor can deliver with its Ir...
i. The speed of a separately excited dc motor is controlled by a one-phase full-wave converter. The field circuit is also controlled by a full-wave converter, see V supply) Vs pk-150V Ra-0.310 L Rf 1...
i. The speed of a separately excited dc motor is controlled by a one-phase full-wave converter. The field circuit is also controlled by a full-wave converter, see V supply) Vs pk-150V Ra-0.310 L Rf 152O E-63V α. 1-35A Figure 3 The AC supply voltage to the armature and field converters is one-phase, 150Vpeak, 50Hz. The armature resistance Ra-0.31Ω, the field circuit resistance Rf-152Ω, and the motor voltage constant is Kv-1.3V/A. The armature current corresponding to the load demand la-35A The...
Q1b) DC Machines [ 6 marks ] You are given a 24 V DC motor. When you connect it to a 24 V supply, under no-load conditions it spins at 2,000 rpm. With the same 24 V supply, when the motor is stalled, the input current is 50 A. i) Calculate the back-emf constant and hence the stall torque of the motor. Find also the armature resistance. [3 marks ] ii) The DC motor has a rated input current of...
3. A 20kW, 250V, 1000rpm shunt excited dc motor has armature and field resistances of 0.2 ohm and 2002. When the motor takes 80A rated current at rated conditions. Draw the equivalent circuit and calculate induced torque at 1200rpm. Explain the starting current limiting methods for DC motors. (30 pts) 4. Explain the conditions for parallel operation of synchronous generators. A three phase, wye connected, synchronous generator is rated 150 MW, 0.85 lagging power factor, 12.6 kV, 60 Hz, and...
Problem 3: DC machine A shunt DC motor rated at V,'. 300 V, with field resistance of Rf 600 0, armature 0.2 , resistance of R, 30.5 A (total current) when rated-load at n, consumes 916.8 rpm. Armature rotational loss (consisting of fan, friction and core loss (consisting of field resistance, armature a) Find Prot (rotational load), Pshaft and efficiency at rated load. - Assume that the rotational loss is constant and P,aft is now 50% in the case of...
3) The armature of a permanent-magnet dc motor has a resistance of 0.72 and draws a current of 50 A when the speed is 1500 r/min when the armature is connected to a source of 48 V, calculate the following: a) The induced emf, EA, and the torque, T, produced at this speed. b) The motor speed, n (in rpm), when the torque is 2 Nm. c) The armature current at 1600 r/min. d) The torque at 1600 r/min. e)...
b) A 1MW, 3300 V, 50 Hz, wye-connected, 3-ф, twenty four-pole, synchronous motor has a synchronous reactance of 3.24 2 per phase. Assume armature resistance is negligible. This machine is connected to an infinite bus-bars at 3300 V. Its field excitation is adjusted to provide P.F-1 at rated load Calculate: 0 the internal generated voltage EA and armature current la at rated conditions (S marks) ii) the maximum power and torqu e that the motor can deliver with its Ir...
i. The speed of a separately excited dc motor is controlled by a one-phase full-wave converter. The field circuit is also controlled by a full-wave converter, see V supply) Vs pk-150V Ra-0.310 L Rf 152O E-63V α. 1-35A Figure 3 The AC supply voltage to the armature and field converters is one-phase, 150Vpeak, 50Hz. The armature resistance Ra-0.31Ω, the field circuit resistance Rf-152Ω, and the motor voltage constant is Kv-1.3V/A. The armature current corresponding to the load demand la-35A The...
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