Does a DC motor have to be turning in order for it to develop torque? a) yes b) no Most DC motor consist of many turns per armature loop as well as many evenly distributed loops per al mature. a) true b) false Brushes a DC motor. a) are part of the electrical circuit in b) provide a sliding electrical contact to the commutator of c) are made of a material which is softer than the commutator segments of d) all of the above

Does a DC motor have to be turning in order for it to develop torque? a) yes b) no Most DC motor consist of many turns per armature loop as well as many evenly distributed loops per al mature. a) true b) false Brushes a DC motor. a) are part of the electrical circuit in b) provide a sliding electrical contact to the commutator of c) are made of a material which is softer than the commutator segments of d) all of the above

Delmar's Standard Textbook Of Electricity

7th Edition

ISBN:9781337900348

Author:Stephen L. Herman

Publisher:Stephen L. Herman

Chapter30: Dc Motors

Section: Chapter Questions

Problem 4RQ

See similar textbooks

Similar questions

(TRUE OR FALSE) - Energy conversion of DC generator is based on the principle ofproduction of dynamically terminal voltage. - Increasing the speed of DC motor, the back emf will decrease but theline current falls. - The current drawn by the armature of DC motor is directly proportionalto torque.
The armature winding of a 4-pole, 250-V DC shunt motor is lap connected. There are 130 slots, each slot containing 8 conductors. The flux per pole is 30 mWb and the current taken by the motor is 35-A. The resistance of armature and field circuit are 0.25 and 150 ohms respectively. If the rotational losses amount to 750W. Determine the (a) gross torque in N-m, (b) useful torque in N-m and (c) the efficiency.
A 4 pole10V, DC shunt motor operates on a load current 10A, having wave connected armature with 200 conductors. The flux per Pole is 25 m Wb. Resistance of shunt field winding is 1 ohm and resistance of the armature is 0.15 ohm. a) based on the back emf voltage, is it possible to be achievable this value? Give reason.
A shunt motor is rotating at 1500 rpm and is powered by a 120V voltage source. The current line resistance is 51-A and the shunt field resistance is 120ohm. If the armature resistance is 0.12ohm, Determine: a) the armature current, b) the back emf (E), c) the total power that is supplied to the motor, d) the power absorbed by the armature, e) power dissipated in the armature. You have to answer all subpart not only first three subpart Either dislike is ready
A series dc motor 20-hp, 500-V, is having armature, series field and shunt field winding resistances of 0.08 Ω, 0.3 Ω and 125 Ω, respectively. If the back – emf is 478 V, determine the motor current when the connection is a) long – shunt. b) short – shunt c) series d) shunt
A 220 V, 4-pole lap wound dc shunt motor has 800 conductors and has a filed resistance of 220 ohm. The motor takes a line current of 15 A at full load and rated speed. Find the additional resistance required in the field winding if the speed of the motor is to be raised by 20 % while maintaining its torque output at previous full load value. Assume linear magnetic circuit for the machine and the resistance of each armature conductor as 40 mohm
A 220V DC shunt motordraws a no load armature current of 2.5A when running at 1400 rpm. Determine its speed when taking an armature current of 60A, if armature reaction weakens the flux by 3%.
1-The main disadvantage of Rheostatic control method of a dc shunt motor, that the speed up to zero is impossible. (True or False) 2-The armature torque of the dc series motor after saturation is proportional to armature current only. (True or False) 3-By potential divider arrangement the speed of d.c shunt motor can be controlled above rated value. (True or False)
A separately excited dc motor has the following parameters: 220 V, 10 A, 1,400 rpm, armature resistance = 2.3 Ω, field excited at rated current. When the armature is open-circuited and rotated at 1,500 rpm by a prime mover, the armature voltage was 250 V. If the motor is now supplied at rated voltage and if it carries 5.6 A armature current, what will be the approximate load torque on the shaft?
Q/ A 250 V dc series motor having armature and field resistance 0.25 ohm and 0.15 ohm respectively runs, at 800 rpm, while taking 50 A from the supply. Assuming the magnetic circuit of the motor to be unsaturated, determine its speed, when a divertor of 0.3 ohm resistance is connected in parallel with the field winding of the motor, which is subjected to a load torque whose torque (a) remains constant regardless of speed, (b) varies in direct proportion to the speed, (c) varies as the square of the speed.
A dc shunt motor runs at 600 rpm on a 240V supply while drawing a line current of 30 A. Its armature and field resistances are 0.5 ohm and 120 ohms respectively. What is the resistance should be placed in series with the armature circuit in order to reduce the speed to 400 rpm. Assume no changes in the armature or field current.
5. A DC shunt motor runs at 9oorpm from a 460V supply when taking an armature current of 25 A. Calculate the speed at which it will run from a 230V supply when taking an armature current of 15A. The resistance of the armature circuit is 0.8 Ω. Assume the flux produced per pole at 230V to have decreased to 75% of its value at 460V.