Industrial Electric Motors and Generators-Electric Machines-Lecture Handout, Exercises for Electric Machines
garjan
garjan

Industrial Electric Motors and Generators-Electric Machines-Lecture Handout, Exercises for Electric Machines

3 pages
2Number of download
1000+Number of visits
Description
This lecture handout was distributed by Prof. Vishvajit Gupta at Bengal Engineering and Science University in class of Electric Machines course. it includes: Industrial, Application, Motor, Speed, Torque, Infinite, Range...
20 points
Download points needed to download
this document
Download the document
Preview3 pages / 3
Download the document

Industrial applications use dc motors because the speed-torque relationship can be varied to

almost any useful form -- for both dc motor and regeneration applications in either direction of

rotation. Continuous operation of dc motors is commonly available over a speed range of 8:1.

Infinite range (smooth control down to zero speed) for short durations or reduced load is also

common.

Dc motors are often applied where they momentarily deliver three or more times their rated

torque. In emergency situations, dc motors can supply over five times rated torque without

stalling (power supply permitting).

Dynamic braking (dc motor-generated energy is fed to a resistor grid) or regenerative braking (dc

motor-generated energy is fed back into the dc motor supply) can be obtained with dc motors on

applications requiring quick stops, thus eliminating the need for, or reducing the size of, a

mechanical brake.

Dc motors feature a speed, which can be controlled smoothly down to zero, immediately

followed by acceleration in the opposite direction -- without power circuit switching. And dc

motors respond quickly to changes in control signals due to the dc motor's high ratio of torque to

inertia.

Industrial Electric Motors and Generators Menu

DC Motors Supplier

Application of DC Shunt Wound Electric Motor:

The characteristics of a DC shunt wound motor give it very good speed regulation, and it is

classified as a constant speed motor, even though the speed does slightly decrease as load is

increased. Shunt-wound motors are used in industrial and automotive applications where precise

control of speed and torque are required.

Typical Shunt Wound DC Motor speed-torque relationship is shown below.

A shunt-wound DC motor has a decreasing torque

when speed increases. The decreasing torque vs

speed is caused by the armature resistance voltage

drop and armature reaction. At a value of speed

near 2.5 times the rated speed, armature reaction

becomes excessive, causing a rapid decrease in

field flux, and a rapid decline in torque until a stall

condition is reached.

docsity.com

Shunt-Wound Motor Applications The characteristics of a shunt-wound motor give it very good speed

regulation, and it is classified as a constant speed motor, even though the speed does slightly

decrease as load is increased. Shunt-wound motors are used in industrial and automotive

applications where precise control of speed and torque are required.

TYPES OF DC MOTORS DC Motors Series-Wound Motor Figure 9 Torque-vs-Speed for a

Series-Wound Motor Since the armature and field in a series-wound motor are connected in

series, the armature and field currents become identical, and the torque can be expressed as

shown in Equation (6-8). (6-8) T KI 2

a The torque-vs-speed characteristics of a series-wound

motor with a constant voltage source are shown in Figure 9. As the speed decreases, the

torque for a series- wound motor increases sharply. As load is removed from a series motor,

the speed will increase sharply. For these reasons, series-wound motors must have a load

connected to prevent damage from high speed conditions.

Series-Wound Motor Applications The advantage of a series-wound motor is that it develops a

large torque and can be operated at low speed. It is a motor that is well-suited for starting heavy

loads; it is often used for industrial cranes and winches where very heavy loads must be moved

slowly and lighter loads moved more rapidly.

Compounded Motor The compounded motor is desirable for a variety of applications because it

combines the characteristics of a series-wound motor and a shunt-wound motor. The compounded

motor has a greater torque than a shunt motor due to the series field; however, it has a fairly constant

speed due to the shunt field winding. Loads such as presses, shears, and reciprocating machines are

often driven by compounded motors.

DC Motors TYPES OF DC MOTORS S In a shunt-wound motor, the field is in parallel, or "shunts" the armature.

docsity.com

In a series-wound motor, the field is in series with the armature.

A compounded DC motor is constructed so that it contains both a shunt and a series field.

A shunt-wound DC motor has a decreasing torque as speed increases.

The characteristics of a shunt-wound motor give it very good speed regulation, and it is classified as a

constant speed motor, even though the speed does slightly decrease as load is increased.

A series-wound motor has a rapidly increasing torque when speed decreases. As load is removed from a

series-wound motor, the speed will increase sharply.

The advantages of a series-wound motor are that it develops a large torque and can be operated at low

speed. It is a motor that is well-suited for starting heavy loads.

Hansen Permanent Magnet DC Motors have unique performance advantages that make them the best

choice for simple, high efficiency DC drives and servo motors. Hansen Permanent Magnet DC Motors

provide nearly instantaneous torque and higher torque overall than wound field motors. With these

torque characteristics and a linear speed torque curve, Hansen Permanent Magnet DC Motors are

perfect for demanding use, especially in applications requiring high starting torque and low inertia loads.

An added benefit of DC motors is easy reversibility by simply changing polarity.

Permanent Magnent:

Typical Applications:

 Mobility (Motorised wheelchairs & stairlifts etc.)

 Leisure (Golf carts & trolleys, caravan & boat movers etc.)

 Process control

 Door operating devices

 Industrial floor cleaners

 Factory transporters

 Medical equipment

 General agricultural

 Scooters

 Pumps & Compressors

 Office equipment

 Marine equipment

 Machine tools

 Printing processing and labelling

docsity.com

no comments were posted
Download the document