What is the load on a dc motor?

1 Answer

Answer :

The device to be driven by the motor.

Related questions

Description : In the actuator arm assembly of a hard disk drive transport, what device can position the magnetic heads to the correct track of a hard disk more accurately than a dc stepper motor?

Last Answer : Voice coil servo.

Description : What part of a floppy disk drive transport uses a dc stepper motor to position the magnetic heads over the recording surface of a floppy disk?

Last Answer : Actuator arm assembly.

Description : Armature reaction in a dc motor causes a shift of the neutral plane in which direction?

Last Answer : Opposite the rotation.

Description : In a dc motor that must be able to rotate in both directions, how is the direction changed?

Last Answer : By reversing either field or armature connections

Description : What causes counter emf in a dc motor

Last Answer : Generator action.

Description : What are the differences between the components of a dc generator and a dc motor?

Last Answer : There are no differences.

Description : What factors determine the direction of rotation in a dc motor?

Last Answer : Direction of armature current, and direction of magnetic flux in field.

Description : What is the effect of motor reaction in a dc generator?

Last Answer : A force which causes opposition to applied turning force.

Description : An open armature connection in a DC propulsion motor could be caused by ____________. A. low-load operation B. clogged ventilation ducts C. sparking at the brushes D. a grounded shunt field coil

Last Answer : Answer: B

Description : A dc cumulatively compounded motor delivers rated load torque at rated speed. If series field is short circuited, then the armature current and speed will a) Both increases b) Both decreases c) Increases and decreases d) Decreases and increases

Last Answer : Ans: Both increases

Description : Regenerative braking (A) Can be used for stopping a motor. (B) Cannot be easily applied to DC series motors. (C) Can be easily applied to DC shunt motors (D) Cannot be used when motor load has overhauling characteristics.

Last Answer : Ans: B Because reversal of Ia would also mean reversal of field and hence of Eb

Description : A dc shunt generator has a speed of 800 rpm when delivering 20 A to the load at the terminal voltage of 220V. If the same machine is run as a motor it takes a line current of 20A from 220V supply. The speed of ... . (B) more than 800 rpm. (C) less than 800 rpm. (D) both higher or lower than 800 rpm.

Last Answer : (C) less than 800 rpm.

Description : Why shouldn’t a DC shunt motor start on the heavy load setting?

Last Answer : A series motor never started at no load and a shunt motor is never started at on load.

Description : What will happen when a DC shunt motor is started with a load?

Last Answer : Starting current will be very high so motor will take more current from supply. It may damage the armature winding.

Description : Why does the speed of a DC shunt motor decrease as the load increases?

Last Answer : Because if the load is increasing then the torque must also be increase. If not then the speed of motor will decrease.

Description : DC series motor should never be started at no-load. Justify. 

Last Answer : At no load the field current (which is also the armature current) is very small and hence the useful air-gap field flux. Also the torque is very small.  As N ∝ 1/Ф the speed rises to ... on the rotating parts they may get damaged. Hence DC series motor should never be started on no-load.

Description : A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to  (A) 0.75 p.u (B) 0.5 p.u (C) 0.25 p.u (D) 0.125 p.u

Last Answer : A dc series motor driving and electric train faces a constant power load. It is running at rated speed and rated voltage. If the speed has to be brought down to 0.25 p.u. the supply voltage has to be approximately brought down to 0.5 p.u

Description : To conduct load test on a dc shunt motor, it is coupled to a generator which is identical to the motor. The field of the generator is also connected to the same supply source as the motor. The armature of generator is ... value of this load resistance is  (A) 1.0 (B) 0.98 (C) 0.96 (D) 0.94

Last Answer : To conduct load test on a dc shunt motor, it is coupled to a generator which is identical to the motor. The field of the generator is also connected to the same supply source as the motor. ... obtain rated armature current in both motor and generator. The p.u value of this load resistance is 0.96

Description : The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 ... .5 A from the same source will be  (A) 48.0% (B) 57.1% (C) 59.2% (D) 88.8%

Last Answer : The armature resistance of a permanent magnet dc motor is 0.8 Ohm. At no load, the motor draws 1.5 A from a supply voltage of 25 V and runs at 1500 rpm. The efficiency of the motor while it is operating on load at 1500 rpm drawing a current of 3.5 A from the same source will be 48.0%

Description : The dc motor, which can provide zero speed regulation at full load without any controller is  (A) series (B) shunt (C) cumulative compound (D) differential compound

Last Answer : The dc motor, which can provide zero speed regulation at full load without any controller is shunt 

Description : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be

Last Answer : A 240 V, dc shunt motor draws 15 A while supplying the rated load at a speed of 80 rad/s. The armature resistance is 0.5 W and the field winding resistance is 80 W. The net Voltage across armature resistance at the time of plugging will be 474 V

Description : In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is :

Last Answer : In a 2 kW, 200 V, 1000 rpm. DC series motor the torque at full load was found to be 0.3 N -m. The torque at half full load in N -m is : 0.075

Description : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ (A) directly proportional to α and Φ (B) ... proportional to α and inversely proportional to Φ (D) directly proportional to Φ and inversely proportional to α

Last Answer : The no-load speed of a single-phase SCR bridge converter fed separately excited dc motor operating at a firing delay angle, α and flux, Φ directly proportional to α and inversely proportional to Φ

Description : A cumulative dc compound motor runs at 1500 rpm. on full load. If its series field is short-circuited, its speed  (1) becomes zero (2) remains unchanged (3) increases (4) decreases

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Description : Circuits which maintain constant voltage or current outputs are called dc voltage or dc current ___.

Last Answer : Regulators.

Description : What is the basic difference between the primaries of ac and dc rate generators?

Last Answer : The method of primary excitation (ac and permanent magnet).

Description : What two factors can cause output dc voltage to change?

Last Answer : Ac line voltage and a change in load resistance.

Description : What causes dc bias energy to be absorbed by avalanche electrons and given up to the microwave field applied to an avalanche transit-time diode?

Last Answer : The negative-resistance property.

Description : The electrons in the beam of a klystron are speeded up by a high dc potential applied to what elements?

Last Answer : The accelerator grid and the buncher grids.

Description : Why does using ac vice dc bias voltage result in a stronger output signal?

Last Answer : Because an ac bias voltage of the proper frequency and level places the input signal away from both steps in the magnetism curve. The result is two undistorted output signals that are combined into one strong output.

Description : What are three advantages of adding an ac bias voltage to the input signal instead of adding a fixed dc bias voltage?

Last Answer : a. Reproduces a stronger output signal. b. Greatly improves the SNR. c. Greatly reduces the natural tape hiss.

Description : Why does adding dc vice ac bias voltage to the input signal result in a poor signal-to-noise ratio (SNR)?

Last Answer : With dc bias, the SNR is poor because only a small portion of the magnetism curve is straight enough to use, thus the output signal is weak compared with the natural tape hiss.

Description : How does dc bias added to the input signal correct the distortion in the output signal?

Last Answer : The dc bias moves the input signal away from the step in the magnetism curve. This prevents the input signal from crossing the zero-point of the magnetism curve.

Description : On the diagram below, name the elements of the vacuum tube and their potentials relative to dc ground. time is an example of what type of transmission?

Last Answer : a. Plate, positive. b. Suppressor grid, negative.

Description : What are the two types of dc operations used to represent mark and space conditions?

Last Answer : Neutral and polar.

Description : What is the purpose of a dc generator that has been modified to function as an amplidyne?

Last Answer : It can serve as a power amplifier.

Description : What are the three classifications of dc generators?

Last Answer : Series-wound, shunt-wound, and compound-wound

Description : Why are drum-type armatures preferred over the Gramme ring armature in modern dc generators?

Last Answer : Drum-type armatures are more efficient, because flux lines are cut by both sides of each coil.

Description : How can field strength be varied in a practical dc generator?

Last Answer : By varying the input voltage to the field coils

Description : What component causes a generator to produce dc voltage rather than ac voltage at its output terminals?

Last Answer : A commutator

Description : Besides setting up the meter for expected voltage ranges, what must be strictly observed when taking dc voltage readings?

Last Answer : Polarit

Description : Why is the dc scale on a multimeter different than the ac scale?

Last Answer : The meter movement reacts to average ac voltage and current and the effective value is desired.

Description : List three meter movements that can measure either ac or dc without the use of a rectifier.

Last Answer : Electrodynamic, moving vane, and hot-wire or thermocouple.

Description : Most large alternators have a small dc generator built into them. What is its purpose?

Last Answer : To provide dc current for the rotating field.

Description : What are the two functions of the servo motor in the system

Last Answer : To move the load and provide feedback data to the error detector.

Description : How do dual-motor dual capstan drives maintain a constant tape tension while operating in either a forward or reverse direction?

Last Answer : Each capstan is driven by its own motor. It maintains tape tension by slowing down one of the motors. When the tape motion is reversed, the opposite motor is slowed down.

Description : What are two advantages of a two-motor reeling system over a take-up control reeling system?

Last Answer : The two-motor configuration runs in both directions and a holdback voltage helps control tape tension, but it does not properly control tape tension during starts and stops.

Description : The drive motor of a 3-1/2", 1.44-MB floppy disk drive spins the disk at what RPM?

Last Answer : 600 RPM.

Description : What is the effect on motor speed if the field current is increased?

Last Answer : Motor will slow down.

Description : What advantage does a shunt motor have over a series motor?

Last Answer : It maintains a constant speed under varying loads.