A separated excited dc machine is delivering 50% rated torque at 20% rated speed. Find the efficiency of the motor at this operating point. The details of the machine are as follows: 1500 kW(rated output power), 600V(rated voltage), 2650A (rated current) 600rpm (rated speed), brush voltage drop = 2V, Filed power input = 50 kW, Ra=3.645 mOhm, La=0.1 mH, Machine frictional torque coefficient = 15 Nm/rad/s. Field current is constant and armature voltage is variable.
A separated excited dc machine is delivering 50% rated torque at 20% rated speed. Find the...
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 separately-excited dc motor with the following parameters: Ra = 0.25 ohm, La = 0.003H, and Kb = 0.35 V/rad/sec. is driving a load of 1-0.0155 ke-m2, B -0.004 Nm/rad/sec with a load torque of 120 Nm. Its armature is connected to a dc supply voltage of 450 V and is given the rated field power. Determine the armature input power of the motor and choose the right answer from the given answer options. 120.5 kW 450 kW 159.6 kW...
6. The speed of a 150 HP, 650 V, 1750 rpm, separately excited DC motor is controlled by a 3- phase full converter. The converter is operating from 3-phase, 460 V, 50 Hz supply. The rated armature current of the motor is 170 A. The motor parameters are Ra = 0.099 2, La = 0.73 mH, and K.D=0.33 V/rpm. Neglect the losses in converter system. Determine i. No-load speed at firing angles a = 0º and a = 30°. Assume...
A separately excited DC motor has the following data P=32kW (rated power); Va=220V (rated voltage); Ia=171A (rated curent); n=1000 rpm (rated speed); Ra = 0.096 ohm a.Calculate the armature voltage to reduce the speed to 900 rpm, assuming the load torque is kept constant? b.Calculate the resistance should be added to armature circuit to reduce the speed to 800 rpm, assuming the load torque is kept constant? c.Calculate the reduction of magnetic flux to reach the speed of 1100 rpm,...
DC-DC Converter Machine Drives D QUE D EA TI C+ ata at I A separately excited DC motor is powered by a full bridge power converter using MOSFET power transistors and freewheeling diodes as shown above, Converter: Vs - 250 V Switching frequency - 5 kHz. Two-quadrant mode: Q3 always open and Q4 always closed. Assume ideal switches and diodes. DC machine: R-50 m2 LA = 300 H Ex -0.2 V/(r/min) Ignore rotational losses and brush voltage drop Answer the...
A 230 V, 1000 rpm, 30 A separately excited motor has armature resistance and inductance of 0.7 Ω and 50 mH respectively. Motor is controlled in regenerative braking by a chopper operating at 800 Hz from a dc source of 230 V. Assuming continuous conduction a) Calculate duty ratio of chopper for rated torque and the speed of 800 rpm. b) What will be the motor speed for duty ratio of 0.6 and rated motor torque? c) What will be...
A 12-pole, brushless, DC motor has a no-load speed of 5000rpm and a stall torque of 50 in-oz when operating at rated voltage of 60V. Testing shows that no-load speed and stall torque vary linearly with applied voltage. Also, with a constant applied voltage the speed decreases linearly as delivered torque increases. Calculate the following: Torque that the motor delivers at 2000 rpm when operated at rated voltage. T a) b) Fundamental frequency of the applied voltage waveform at this...
3) A saperately excited DC motor has the following parameters: Ra = 10 Ke = 0.4 V/rpm. Wb O = 0.2 Wb The motor speed is controlled by a full-wave bridge rectifier. The firing angle is set at 45, and the average speed is 1500 rpm. The applied AC voltage to the input of the bridge rectifier is 220Vrms - 50 Hz. a) (10p) Please draw the complete circuit. (converter + motor) b) (10p) Please find the armature current. c)...
3) A saperately excited DC motor has the following parameters: Ra = 10 Ke = 0.4 V/rpm. Wb 0 = 0.2 Wb The motor speed is controlled by a full-wave bridge rectifier. The firing angle is set at 45°, and the average speed is 1500 rpm. The applied AC voltage to the input of the bridge rectifier is 220Vrms - 50 Hz. a) (10p) Please draw the complete circuit. (converter + motor) b) (10p) Please find the armature current. c)...
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...