Query/Problem Presentation 2

[Shortstub]

A suggestion to the lady and gentlemen of the this forum:

To eliminate a great deal of second-ary (excuse the pun)guessing, how about presenting queries and problems with the following data (in the relevent order) in mind:

1) Supply Features.
2) Motor Parameters.
3) Starting Method.
4) Driven-Machine Characteristics.

 

[jbartos]

Suggestion: Please, would you post a sample what you are really after?

 

[Shortstub]

Jbartos,

I'm asking that an initiator provide enough facts about a motor/system problem or query to enable effective analysis. Do you not agree, language barrier and semantics aside, that some of the threads continue for too long before salient points are revealed?

Now, do you really want me to present a list of items? Per category?

 

[jbartos]

Suggestions marked ///\\To eliminate a great deal of second-ary (excuse the pun)guessing, how about presenting queries and problems with the following data
///Which category of problems with the following data do you have in mind, specifically?\\ (in the relevent order) in mind:

1) Supply Features.
///Please, define "Supply Features" since this terminology is not defined in IEEE Std 100 "Dictionary"\\2) Motor Parameters.
///There is a myriad of motor parameters. Would motor nameplate parameters suffice?\\3) Starting Method.
///DOL, Soft Start, Reduced Voltage Start\\4) Driven-Machine Characteristics.
///Torque-Speed Curve, Duty Characteristic, Load Fluctuation, etc.\\\

 

[Shortstub]

Good start!

 

[jbartos]

Suggestion: Please, could you be more pro-active?

 

[Shortstub]

Jbartos,

Let me give you an example of a query of the type I'm characterizing, i.e., one lacking sufficient detail:

A pumping station consists of two generators, A&B. They serve a 480 V substation supplying power to 4 pumps.

Gen A is 5kV, 680 kVA, 0.8pf. Gen B is 480V, 1000kW, 0.8pf. Each of the pumps is 300Hp.

The problem is that every time the generators operate in parallel, the Gen B incomer trips on ground-fault.

What's wrong?

Oh, I forgot, there is also a utility tie.

Also, Gen A is connected via a stepdown transformer.

Furthermore, the pump motors are equipped with VFD's, etc.

One is painted green the others aren't.

Now, I understand the principle of asking probing question... I also teach "Problem Solving" techniques to students in a post-secondary school.

My, point is that the info presented is so sparse as to take a lot of time eliciting meaningful data.

You, yourself, in an earlier forum, expressed disdain at the incompleteness of info, albeit, perhaps not as pointed as my suggestion is. We older, and I apologize if my characterization of you is in error, should be providing knowhow, and techniques, commensurate with our professional experience.

That's all I meant by this forum. It was not intended to embarass anyone, nor step on fragile toes.

 

[jbartos]

Suggestion: This Forum intent is to provide eng-tips. Problem solving and complete solutions that are provided by some volunteers are part of their generosity added to eng-tips. There are very few gifted volunteers that are capable of offering unique ideas continuously, all the time. Incidentally, I am in a competitive business, not on any academic endowment account or on a government payroll. Your suggestion appears to be pertinent to more fortunate professionals.

 

[Shortstub]

Jbartos,
To satisfy my curiosity, what is your definition of "more fortunate professionals?"

 

[jclough]

I may be going out on a limb here but i think that each of us puts up whatever information we feel is relevant when we post a question. Sure some of the posts are really vague but they normally don't get much in the way of response.


I believe that we also realize and depend on the fact that the real strength of this board is the varied backgrounds and experiences of its users. All of the information is given freely and should be treated as the gift it is.



Though i can't speak for Jbartos, when he refers to "more fortunate professionals" It looks like he means those who are employed by the government or similarly funded organizations. You know... the ones where employment seems to be related more to politics than performance.

We all have problems to solve and need to get them done quickly. In this economy we also need to do it in less time and without tools. . If they don't get solved we don't eat.

 

[electricpete]

I agree with Shortstub - there is a lot of time spent asking for data. Often it is the same questions.

In case of a motor vibration problem
- Which frequencies are dominant
- Which positions have highest vibration
- machine description - speed horsepower, coupling method, driven equipment, bearings sleeve or roller etc
- Is there a history of previous vibration levels on this machine? On similar machines?
- When did the vib start and what was anything done to the machine around that time?

All of these and more would be useful. I'm sure that others would add questions. Maybe there should be a FAQ listing the types of info that would be helpful for a particular type of problem/question. Then when someone posts a question with very little info you can point 'em to that FAQ.

 

[Marke]

Hear Hear!!!

As someone who has spent a lifetime solving motor control problems by remote control, I have often been heard to make utterances along the lines of "my ability to help is limited by your ability to ask for help!" Too often I have been contacted about problems and presented with an incorrect hypothesis rather than the facts. This has totally clouded the picture and made the solution much harder to arrive at. One of the best people that I have worked with in problem solving, is emanently qualified, but when he calls me in (by phone fax or email), I get a complete unfiltered picture of the problem and we get a good strike rate in very short time. If you are unable to solve the problem yourself, do not make assumtions or judgments about what information is irrelevant. Such an assumption could be the reason that you have not seen the solution yourself. In my problem solving role, I ask the person in the field to be my eyes, nose, ears and hands and to report the whole picture. This may seem overkill, but it works very well!
Best regards,

Mark Empson

http://www.lmphotonics.com

 

[jbartos]

Comment: A fortunate professional is one who actually admits that "I have been fortunate in my profession to succeed in ..."

 

[TWW]

Definition of a more fortunate professional: One that still has a job!

 

[advidana]

A lot of the questions are from rookies with rookie questions. Having a format method at asking questions on the web would not work. I don't think a lot of these guys have any idea what to ask, much less how to asked it properly.

I believe that the response to the questions are great. It helps give a different propective to these questions from a broad range of electrical engineering. If I can anwser a question I will. No matter how it was asked. I believe it help the profession.

So, no I do not agree with you. But, keep the ideas and questions coming anyway.
advidana

 

[GGOSS]

Hello all,

Interesting discussion! I too have spent the bulk of my lifetime troubleshooting by 'remote control'. Through this I have learnt and developed many techniques for 'extracting' information from both highly technical and non-technical people.

I would agree that offering solutions is made easier when all the facts are presented to the troubleshooter, however believe that the people asking for assistance often don't have sufficient knowledge and/or experience to decifer what information is and isn't important. Lets face it, if they did, they wouldn't be asking for our help!

In addition, far too often the person requesting assistance has already made up his/her own mind about what may or may not be the cause, and therefore the information they present is skewed accordingly.

Based on the above, I much prefer to ask for information that will assist me to identify the best possible solution.

Regards,
GGOOSS

 

[jbartos]

Comment: Some postings above cover fairly delineated areas, e.g. problem solving. This means that one is somewhat specialized and set to do what one chose or has to do. Beside problem solving or troubleshooting, many postings have original nature in areas of concepts, equipment/material selections, standards compliance, safety concerns, etc. Some businesses must meet challenges as they come with what is available.