separately excited series, shunt, compound DC motor: *Describe how does decreasing the field current IF affect...
separately excited series, shunt, compound DC motor:
*Describe how does decreasing the field current IF affect the speed versus voltage characteristic and constant K1 of a separately-excited dc motor. K1=(n2-n1)/(E2-E1)
*Describe how does decreasing the field current IF affect the torque versus current characteristic and constant K2 of a separately-excited dc motor? k2=(T2-T1)/(I1-I2)
*Briefly describe how the speed varies as the mechanical load applied to the series motor increases, i.e. as the motor torque increases.
Homework Answers
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separately excited series, shunt, compound DC motor:
*Describe how does decreasing the field current IF affect...
Q1. Draw the equivalent circuits of a separately excited and a shunt DC motor. [20] Q2....
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 separately excited DC motor is fed from a variable DC source and it drives a...
A separately excited DC motor is fed from a variable DC source and it drives a variable mechanical load as shown in Figure Q4b. The excitation current If is held constant during the motor operation. (i) How can the motor direction be reversed? (4 marks) (ii) Explain what will happen to the current Ia, the internal voltage Eg, and speed if the mechanical torque increases whilst the DC input voltage VT is held constant. (4 marks) (iii)Explain what will happen...
A separately-excited DC traction motor of a metro train is in series connection, i.e., the armature...
A separately-excited DC traction motor of a metro train is in series connection, i.e., the armature and the field windings are connected in series with a common DC power source. The voltage of the DC power source is I (a) Please show that the angular velocity of the rotor is KT K where o is the is the angular velocity of the rotor, Ra is the resistance of the armature, Rris the resistance of the field windings, T is the...
Please explain the no-load characteristics for shunt and separately excited DC motors. How will rotor speed,...
Please explain the no-load characteristics for shunt and separately excited DC motors. How will rotor speed, armature current and field current be effected for both at no load?
A DC Shunt motor takes a current of 50A on a 440V supply runs at a...
A DC Shunt motor takes a current of 50A on a 440V supply runs at a speed of 1000rpm, with an armature resistance of 0.5Ω and a filed resistance of 100Ω.A Chopper is used to control the speed of motor in the range of 400-800rpm having constant torque. The on period of chopper is 2ms, with field supply voltage from 440V.Determine range of Frequencies of Chopper.
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...
Given a 1/4 hp, separately excited, dc motor with the following parameters: K = 0.61, R, 15Ω, La-...
I can not seem to get the right answers. Thank you!
Given a 1/4 hp, separately excited, dc motor with the following parameters: K = 0.61, R, 15Ω, La-120mb. J = 0.005, and b = 0.0006. The armature voltage is controlled by a 120-V dc PWM source operating at 100 Hz 1. What is the armature current if the no-load speed is 1800 rpm when the armature supply is operated at a 100% duty cycle? 2. What is the no-load...
2. A dc chopper is used for regenerative braking of a separately excited dc motor. The...
2. A dc chopper is used for regenerative braking of a separately excited dc motor. The dc supply voltage is 400V. The motor has ra=0.2 ohms. Km=1.2 V-s/rad. The average armature current during regenerative braking is kept constant at 300A with negligible ripple. For a duty cycle of 60% for a chopper , determine a) Power returned to the supply. b) Minimum and maximum permissible braking speeds and c) Speed during regenerative braking.
A separately excited DC shunt generator produces a no-load voltage of 150 Vdc at 1200 RPM....
A separately excited DC shunt generator produces a no-load voltage of 150 Vdc at 1200 RPM. If the armature resistance is 3 Ohms, calculate the output voltage under the following conditions: (Note all calculations for each problem are to be performed from the base values given above). a) The speed is reduced to 875 RPM. Vout = __________________ b) The field current is increased by 22% (assume a linear field current/flux relationship). Vout = __________________ c) The speed is increased...
solve it now please A 220 V, 1000 rpm, separately excited dc motor is fed from...
solve it now
please
A 220 V, 1000 rpm, separately excited dc motor is fed from a three-phase controlled three-phase ac-dc converter through 220 V (line value-rms value), 50 Hz ac-source. It is required to apply 220 V (dc-value) across the motor terminals. What is the firing angle if the motor speed is 1000 rpm and takes 10 A ripple-free current. The armature resistance is 1 ohm. The field circuit with 198 ohms is fed from a fully controlled single-phase...
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 separately-excited DC traction motor of a metro train is in series connection, i.e., the armature and the field windings are connected in series with a common DC power source. The voltage of the DC power source is I (a) Please show that the angular velocity of the rotor is KT K where o is the is the angular velocity of the rotor, Ra is the resistance of the armature, Rris the resistance of the field windings, T is the...
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...
I can not seem to get the right answers. Thank you!
Given a 1/4 hp, separately excited, dc motor with the following parameters: K = 0.61, R, 15Ω, La-120mb. J = 0.005, and b = 0.0006. The armature voltage is controlled by a 120-V dc PWM source operating at 100 Hz 1. What is the armature current if the no-load speed is 1800 rpm when the armature supply is operated at a 100% duty cycle? 2. What is the no-load...
solve it now
please
A 220 V, 1000 rpm, separately excited dc motor is fed from a three-phase controlled three-phase ac-dc converter through 220 V (line value-rms value), 50 Hz ac-source. It is required to apply 220 V (dc-value) across the motor terminals. What is the firing angle if the motor speed is 1000 rpm and takes 10 A ripple-free current. The armature resistance is 1 ohm. The field circuit with 198 ohms is fed from a fully controlled single-phase...
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