A 220 V dc shunt motor develops a total torque of 100 N-M and takes 29A at 600 rpm. The armature and shunt field resistance are 0.3 ohm and 220 ohms respectively. If the speed is to be increased to 800 rpm determine the percentage reduction of the field and additional resistance to be inserted in the field circuit. The torque develop at 800 rpm is 70 N-M.

A 220 V DC series motor runs drawing a current of 30 A from the supply. Armature and field circuit resistances are 0.4 and 0.1 respectively. The load torque varies as the square of the speed. The flux in the motor may be taken as being proportional to the armature current. To reduce the speed of the motor by 50% the resistance in ohms that should be added in series with the armature is

200 +21. If maximum torque of an induction motor is kg-m at a slip of 12%, the torque at 6% slip would be...... kg-m. 1 (a) 100 (b) 160 (c) 50 (d) 40 B, 1993)

need asap A dc series motor runs at 1000 rpm when taking 20-A at 200-V. Armature resistance is 0.5-ohm. Series field resistance is 0.02-ohm. Find the speed for a total current of 20-A when a diverter resistor of 0.2-ohm is used across the series field. Flux for a field current of 10-A is 70 % of that for 20-A.

L-1). The 3-phase wound-rotor induction motor has .... . a) high starting torque b) low starting current c) both "a" and "b" d) neither "a" nor "b" L-2). The 3-phase wound-rotor induction.........a) motor has a wire wound rotor b) motor's rotor can be connected to an external resistive load by way of slip rings and brushes c) motor requires more maintenance than the 3-phase squirrel-cage induction motor d) all of the above L-3). The 3-phase wound-rotor induction motor's rotor circuit's resistance should be adjusted so it is__________ during starting. a) low b) high c) either "a" or "b" d) neither "a" nor "b" L-4). Will a 3-phase wound-rotor induction motor start with no external circuit connected to its rotor leads? a) yes b) no

A 240-volt series motor has an armature resistance of 0.42 ohm and a series-field resistance of 0.18 ohm. If the speed is 500 rpm when the current is 36 A, what will be the motor speed when the load reduces the line current to 21 A? (Assume a 3-volt brush drop and that of the flux is proportional to the current.). Ans.: 1435 rpm show diagram and step by step process

A four-pole induction motor drives a load at 2500 rpm. This is to be accomplished by using an electronic converter to convert a 400-V dc source into a set of three-phase ac voltages. Find the frequency required for the ac voltages assuming that the slip is 4 percent. The load requires 2 hp. If the dc-to-ac converter has a power efficiency of 88 percent and the motor has a power efficiency of 80 percent, estimate the current taken from the dc source.

1. A fundamental DC motor is shown below. VTerminal = 90V. The running current, I = 5A and the rotor resistance, R = 4 ohms. Answer the following: CEMF or E at the running condition = , Power delivered by the source at the running condition = Power converted to mechanical power at the running condition Power lost in heat by the rotor resistance = Show your work for each calculation. Suggest that you clearly mark the schematic. frut

pole. 50-Hz. 3-ϕ induction motor has a full-load speed of 950 rpm. At half load its speed would be ..... rpm a) 475 b) 500 c) 975 d)1000

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