Q4. A 300 V series motor draws a current of 50 A. The field resistance is 40 mΩ and the armature resistance is 0.2 Ω. Determine the maximum efficiency of the motor.
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Q4. A 300 V series motor draws a current of 50 A. The field resistance is...
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...
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...
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...
a) The input current to a 220 V, short-shunt compound motor at no load is 6 A. The shunt- field circuit resistance is 220 Ω; the armature resistance is 0.112, and the series-field resistance is 0.1 Ω, what is the stray power loss ? (b) Assume the input rating of the motor in Part (a) to be 66 A at 220 V with a no-load speed of 1000 rpm. If the stray power loss varies as the counter-electromotive force and...
A 120-V, series-wound motor has a field resistance of 4.0 and an armature resistance of 2.5 . (a) Determine the current drawn by the motor at the very instant it is switched on, i.e., when it has not started to rotate. (b) When it is operating at nominal speed, a back emf of 85.0 V is generated. How much current is drawn in this case? (c) What is the furnished mechanical power? (d) How much power is dissipated?...
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...
Problem 6: A 230-V shunt motor has an armature resistance of 0.05 Ohms and a field resistance of 75 Ohms. The motor draws 7 A of line current while running light at 1120 rpm. The line current at a certain load is 46 A. (a) What is the motor speed at this load? (b) At this load, if the field circuit resistance is increased to 100 Ohms, what is the new speed of the motor? Assume linearity between the flux...
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
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...
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)...