A DC Shunt motor takes a current of 50A on a 440V supply runs at a...
A shunt motor has an armature resistance of 0.25 W. The motor takes 125 A from a 400 V supply and runs at 1000 rpm. If the total torque developed remains unchanged, calculate the speed and armature current if the magnetic field is reduced to 80% of the initial value.
A 240V DC shunt motor runs at 800rpm at no load. Determine the resistance to be placed in series with the field so that the motor runs at 950rpm when taking an armature current of 20A. The field resistance is 1600 and armature resistance is 0.40. Assume that the pole flux is proportional to the field current Additional Rf= A 240V DC shunt motor runs at 800rpm at no load. Determine the resistance to be placed in series with the...
Q1. Draw the equivalent circuits of a separately excited and a shunt DC motor. [20] Q2. Derive the speed-torque relation for a DC motor: [40] 0 = VR, Kø (KØ)??ind Q3. A DC motor's speed can be controlled by either changing the field resistance, changing the armature voltage or changing the armature resistance. Of these three, which one is the best method for DC motor speed control and which is the worst? Give reasons. [40]
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
QUESTION 1 A) (10 marks) A 10 kW, 250 V DC self-excited shunt generator, with an armature resistance of 0.1 ohm, is delivering 80 % of rated power to the mains at rated voltage when being run at 1000 r.p.m. (revolutions per minute). The field circuit resistance is 220 ohms. The brush contact drop is 0.5 V and rotational (mechanical) losses are 750 W Calculate The induced voltage The electromagnetic torque developed The shaft torque The overall efficiency B) (15...
A 250V, 50A separately excited DC motor has armature resistance of 0.8 ohms (including brushes) and field resistance of 100 ohms. Kf for this motor is 1.5 V/(A.rad/sec). The armature circuit can carry up to 50A for a short time period. It is desired to run it with a 250 V voltage source in no load conditions with the speed of 1500 r/min. a) Explain the required equipment and steps. b) Draw the circuit for steady-state operation with the speed...
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...
A 250-V shunt-connected DC motor runs at 1500 rpm when it is not connected to any external load. When the motor is connected to an external load, it draws a line current of 40A. The motor has an armature resistance of 1 ? and a field circuit resistance of 100 ?. Assume that the rotational loss torque is 2 Nm and is independent of the speed (a) Find the line current of the motor when there is no external load....
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.
A 220 V DC shunt motor has an armature resistance, Re-0.1 S2, a field resistance, Ry=100 12, and negligible rotational losses. Under certain load conditions, the shunt motor runs at 1600 rpm while drawing a total current, I = 100 A. Determine: a. the output power of the motor; b. the output torque in N-m; and, c. the efficiency Without making any changes to the applied voltage or the field, the motor operates with a new M mechanical load that...