53&cmid%3D11610 es This course A 240-V, 100 A armature full-load line current, 1500 RPM, cumulatively-compounded DC motor is considered in this problem. Its characteristics are given below: RA+Rs = 0.202 RF= 140 2 Radj = 160 2 NF =2000 turns NSE= 16 turns This motor has compensating windings and interpoles. The magnetization curve for this motor at 1500 RPM is shown in a tabular form below 0. 0.1 0.2 0.4 0.5 0.6 0.8 1.0 1.2 1.6 1.8 2.0 2.2 2.4 If,A EA.V 6.0 25 50 110 135 160 205 235 255 275 285 288 290 291 What is the full-load speed of this motor? Select one: a. Full-load speed n = 1875 RPM b. Full-load speed n = 1200 RPM OC. Full-load speed n = 1610 RPM d. None

QUESTION 2 a) Draw the equivalent circuit and torque-speed characteristic curve for a series DC motor. b) Briefly explain the induced torque occurs in a series DC motor. e) A 20-hp 240-V 76-A 900 rimin series motor has a field winding of 33 turns per pole. Its armature resistance is 0.09 2, and its field resistance is 0.06 2. The magnetization curve expressed in terms of magnetomotive force versus Ex at 900 rimin is given by the following table: Table Q2 c): The magnetomotive force table for a de motor taken at 900r'min E. V 95 150 188 212 229 243 F.A tuus 1000 1500 2000 2500 500 3000 If the motor running at 33 percent of the full-koad armature current, determine: ) The motor's power converted from electrical to mechanical form, Prene i) The motor's torque, Tnit ii) The motor's speed, n

. Explain how the pulsating mmf of a single-phase induction motor may be considered equivalent to two oppositely-rotating fields. Develop an expression for the torque of the motor. A 125-W, 4-pole, 110-V, 50-Hz single-phase induction motor has the no-load rotational loss of 25 watts and total rotor copper loss at rated load of 25 watts at a slip of 0.06. At a slip s = 0.06, what is the power input to the machine ?

An 8 pole DC shunt generator with 900 wave-connected armature conductors supplies 10ohm  at 500 V when driven at 500 rpm. The armature resistance 0.4ohm and the field resistance is 250ohm . Determine:                                     . .                                   2 1.1 The flux per pole                       2.1.2 The armature current for maximum efficiency if the rotational losses are 10% of the ar- mature copper losses .                                    3.2 A series motor runs at 600 rpm while drawing 40-A from 600-V supply. The total re- sistance of the armature and the field is 0.5-ohm. Determine the value of the additional re- sistance required in series with armature to reduce the speed to 450 rpm if the load toque is:                                      3.2.1 Constant                                   3.2.2 Proportional to the square of the speed .

AA a QUESTION A 750 kW, 3300V, 50 Hz, wound-rotor three-phase induction motor with a star-connected stator winding has a star-connected rotor winding with effective stator/rotor turns ratio of 3.6. The rotor resistance and rotor leakage inductance are 0.0296 2 and 1.7 mH respectively. The stator winding resistance, the stator leakage inductance, and the mutual inductance can be neglected. (a)Calculate the stator current and power factor at a slip of 0.03. (b)Calculate the torque developed at this load. (c) Calculate the stator current and power factor when starting with rated voltage and with the slip-rings short-circuited. (d) What is the main disadvantage of starting big motor using the method described in part (b)? (e)Calculate the resistance of a star- connected external resistor bank that should be connected in the rotor circuit to limit the stator current on starting to 150 (f)By what factor does the addition of the ||| <

Three phase induction motor has rating of 50 kW, 960 rpm, 400 V. 50 Hz, 6-pole. The motor parameters are R = 0.08 N, R' = 0.1 N, X = X = 0.3 N and the moment of inertia 10 kg m². It is required to stop the motor from its no load speed under reverse breaking operation. Find the required value of external resistance that need to put in rotor circuit such way that breaking will be achieved with minimum time. What is breaking time.

1. The operation of Commutator in DC Motor is * O a) to convert dc to ac O b) to convert ac to dc O c) to convert fixed dc to variable dc O reverse the current direction in the rotating windings each half turn

Sketch the torque versus speed characteristic for a series-connected dc motor.

3.An induction motor has a rotor resistance and reactance at standstill of 0.1 ohm and 3.5 ohm respectively. At standstill the voltage induced to the rotor is 60volts per phase. If the slip is 5%, determine the rotor current