assignment questions on DC Motors

[rickrude]

assignments are my exams.

I need help with the following questions.

Describe the constructional features and characteristics, of a d.c motor that would be used in starting a motor vehicle and also a different type of d.c motor that would be used on an overhead crane. identify another application for both these motors?

So far the internet is not helping. If any one has the info for me it will help me continue and get the correct answers.

Thanks Alistair

 

[Rockyd]

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Don't think this is what you had in mind, but would get you close....
I still use my 2nd edition.

Welcome to the Forum!

 

[rickrude]

not what i had in mind, after hours of looking i have found a few bits of information

other than a welding machine what other application can a DC generator be used for?

 

[hillbilly]

This may help you get started.

http://www.howstuffworks.com/search.php?terms=dc+motor&x=34&y=26

steve

 

[rickrude]

seems to give me lots of different information not actually to the point on what i need. very much appreciated thanks

 

[Doug S.]

Well a characteristic of a car starter motor would be that it would fit in the car, and probably run on 12vdc. Another app. would be a truck starter. ... ... ...
Sorry I couldn't resist.

I think your instructor is trying to get you to think about the application, and then consider what the characteristics might be needed based on the demands of the application.

Probably not the answer you are looking for, but it should help...

Good Luck,

Doug S.

 

[Besoeker]

assignments are my exams.

I need help with the following questions.

Describe the constructional features and characteristics, of a d.c motor that would be used in starting a motor vehicle and also a different type of d.c motor that would be used on an overhead crane. identify another application for both these motors?

So far the internet is not helping. If any one has the info for me it will help me continue and get the correct answers.

Thanks Alistair

DC motors can be shunt wound, series wound, or compound which is a bit of both. Each has different characteristics and the application will determine which is the most suitable choice.
Can you go from there?

 

[rickrude]

got some good info now on dc motors thanks. the only thing i need to write about is another app for a DC GENERATOR other than a welding machine. Completely stuck on this one!

Any one good at motor equations? my god they are complicated!

 

[Besoeker]

got some good info now on dc motors thanks. the only thing i need to write about is another app for a DC GENERATOR other than a welding machine. Completely stuck on this one!

Any one good at motor equations? my god they are complicated!

For DC machines, and I deal with them on a regular basis, just two relationships can get you by for most things:

T = k1BI
Torque is proportional to the product of armature current (I) and field flux (B).

E = k2Bv
Generated back EMF is proportional to the product of flux and velocity (v).

These are applicable to both motoring and generating* and give you a fundamental idea of how the main parameters are related and what happens if you change them.

*There is no fundamental difference between the motor and generator. The same machine can do both. What changes it from one to the other is the difference between terminal voltage and generated back EMF. If the terminal voltage is higher, the machine runs as a motor. Obviously it is vice versa in the generating mode. The actual difference is small - typically 5% or less for the machines I deal with. It is mostly the voltage difference required to make the current flow through the armature - often called IR drop.


For an application try googling unwind brake generator.......
Well, you don't want all the work done for you, do you?