Motor

The "heaters" (thermal overloads) on the motor starter are for overcurrent protection. The fuses upstream are for short- circuit protection only.

A general rule of thumb is to size the heaters at 120% FLA and the upstream fuse @ 175% for a dual element time delay, or 300% for a non-time delay fuse.

This is per U.S. N.E.C. ( National ElectricCode)

This forum does not exist to help you cheat on your homework or test. If you are studying, what value is there is just having someone else give you the answers instead of learning how to find them in your study materials?

Unless you are studying to be in Management...

Just to enlighten you I am a woman with curiosities and this forum IS for questions I don't have answers to.

Thank you

Actually, this forum is for questions that may be beyond the knowledge of the general public, or even engineers who may want to obtain knowledge outside their sphere of practice or study, or with situations not "covered", so to speak, in texts or easily available reference materials.

Many of the things you have asked for can be referenced in commonly available media in libraries or other media outlets.

Please try the common methods that we in the profession have used for decades; then, if you have further questions that you can't find answers to, or need further assistance, then please turn to these forums.

That's cool. Give us some background on what kind of test you're up against and we might be able to recommend some good study sites. We're always glad to help people learn, and one of the best ways is to guide people toward the resources they need.

This question and the others you have posed all sound like homework questions. They do not come across as the questions of someone with ordinary curiosity, because then, we'd expect you to present some context for the question.

For example, one might ask: "I've noticed that the motor on my drill press becomes quite warm when drilling large holes through thick steel. I am concerned that I might be overloading the motor. Is the motor likely to have some protective device in it that would perhaps disconnect it in a serious overload, or should I check that the breaker feeding the press is not too large?"

Such a question would get helpful responses. Your several questions, on the other hand, are all very similar, and all sound like test questions or homework questions for a survey course in technology, perhaps. Each one sounds as if it is asking for a pat answer, namely "the answer in the book".

Sorry we can't be more helpful: we don't do homework, for ethical reasons.

Perhaps if you rephrase your question to put it in some context to assure us that we are not simply answering homework questions, then we'd be more helpful.

For you, the most helpful and appropriate form of overcurrent protection would be for you to hold onto the uninsulated A phase of a 4160V line while dipping your bear foot into a nice cool stream.

'F'ing tard.

There is some sense in this discussion.This forum has been conceived by Global Specifications, which is site for engineering products, processes etc. Actually it is expected that questions which are technical in nature and have arisen after day to day work in industry.Such questions which are posed by qualified engineers/technicians who have some working experience are posted.It is sort of Brain Storming forum where knowledge gained by seniors is utilized for solving the problems. Of late questions asked are very preliminary in nature and some are not looked into by seniors. Many fresh students find it as short cut do their assignment for academic purpose instead searching other sources for basic information.I think this forum should not be turned into a education center for non technical persons. This my personal opinion. Suresh.Sharma