Poll for test question

[RichB]

Ok here we go again--let's see if I can get this to be a poll:

What happens to RPM when you have a 4 pole motor operating at 60Hz and 240 Volt and change it to a 6 Pole motor?

You have a formula sheet with the following formula on it--P=(f)(120)/RPM

 

[luckylerado]

What happens to RPM when you have a 4 pole motor operating at 60Hz and 240 Volt and change it to a 6 Pole motor?

More poles @ Same frequency = Less RPM.

 

[jumper]

I assume you are trying to show that as P increases, RPM must decrease. Basic algebra.

 

[RichB]

Correct--I am trying to see if our guys know that or how to manipulate the formula--

 

[kwired]

What is the experience level of those the test is intended for?

 

[JFletcher]

Decrease. P = (f * 120)/RPM. P ~ x/RPM. Thus, P ~ inverse of RPM. As P increases, RPM decreases.

 

[RichB]

What is the experience level of those the test is intended for?

Last year apprentice to Journey level

 

[RichB]

We know the answer--what we are asking is, Is this question understandable and make sense as written--Does it convey that we are looking for what happens to RPM with just a change in poles--

The reason this is being put to you folks is, we have an ex rewinder working for us and he says that this is an impossible question because you cannot rewind or change a 4 pole motor to a 6 pole--which is NOT what the question asks, we think. Just looking to get you input on that!!

Thanks folks!!

 

[luckylerado]

How about this then.

"What is the relationship between synchronous speed and the number of poles in an induction motor?"

Frequency in this case makes no difference as it is unchanged.

 

[kwired]

We know the answer--what we are asking is, Is this question understandable and make sense as written--Does it convey that we are looking for what happens to RPM with just a change in poles--

The reason this is being put to you folks is, we have an ex rewinder working for us and he says that this is an impossible question because you cannot rewind or change a 4 pole motor to a 6 pole--which is NOT what the question asks, we think. Just looking to get you input on that!!

Thanks folks!!

I sort of thought same thing when I first read it, you can't (easily) change the number of poles, but is much easier to replace a 4 pole motor with a 6 pole motor. So maybe ask what happens if you replace a 4 pole motor with a 6 pole motor and maybe there will be less confusion.

 

[JFletcher]

We know the answer--what we are asking is, Is this question understandable and make sense as written--Does it convey that we are looking for what happens to RPM with just a change in poles--

The reason this is being put to you folks is, we have an ex rewinder working for us and he says that this is an impossible question because you cannot rewind or change a 4 pole motor to a 6 pole--which is NOT what the question asks, we think. Just looking to get you input on that!!

Thanks folks!!

You can change it out with a 6 pole; maybe rephrase the question to include the word "out", or this:

"What happens to RPM when you have a 4 pole motor operating at 60Hz and 240 Volt and change it to a 6 Pole motor?"

to this:

"What happens to RPM when you have a 4 pole motor operating at 60Hz and 240 Volt and replace it with a 6 Pole motor?"

 

[Dennis Alwon]

You can change it out with a 6 pole; maybe rephrase the question to include the word "out", or this:

"What happens to RPM when you have a 4 pole motor operating at 60Hz and 240 Volt and change it to a 6 Pole motor?"

to this:

"What happens to RPM when you have a 4 pole motor operating at 60Hz and 240 Volt and replace it with a 6 Pole motor?"

That would be a different motor so alot of assumptions would need to be made. Not sure if that is more confusing or not. I think the first question works fine although it assumes you can make the 4 pole a 6 pole. IMO, that's okay because it is just a test question and not a reality situtation

 

[K8MHZ]

IMO, that's okay because it is just a test question and not a reality situtation

So, you are okay with the fact some that test questions are written in a manner independent of reality?

FWIW, I am not, never have been and never will be. As close as I can get is simply accepting the fact that those kind of questions exist and there isn't much I can do about it. But I will never be 'okay' with it.

 

[iwire]

So, you are okay with the fact some that test questions are written in a manner independent of reality?

I absolutely fine with those types of questions, they make you use your intellect not your memory.

 

[K8MHZ]

I absolutely fine with those types of questions, they make you use your intellect not your memory.

Do you think that better questions based upon reality somehow negate the use of intellect to arrive at the correct answer?

Questions not based in reality border on, and sometimes are, 'trick questions'. I don't like trick questions and think they have no place on tests.

FWIW, I am good at tests. The questions in question don't present a hindrance to me, but I know they really mess with others, that's why I don't like them. I never will like them, even if I am never successfully tricked by one.

Testing should reflect a person's ability to perform in a given area. Testing should not be about who knows how to take tests better and who knows how to deal with trick questions. I had a real estate course that incorporated 'test taking' as a subject. It was a great subject and I learned a new skill. That class was in 1983. In 2002 I took my final NJATC exam and got 101% on it. I probably scored at least 10 percent higher because I knew the 'art' of test taking.

 

[Besoeker]

Correct--I am trying to see if our guys know that or how to manipulate the formula--

For many of us with experience in that field, we don't have to do the algebra even though we can. We just know that a 4-pole motor nsync is 1800 rpm on 60Hz and 1500rpm on 50Hz and it's simple arithmetic from there.

My age is showing................

 

[dkidd]

I agree with the rewinder.

 

[iwire]

Do you think that better questions based upon reality somehow negate the use of intellect to arrive at the correct answer?

I think both types of questions (reality vs theoretical) are appropriate in a test.

It is really not a test of your intellect to answer a question based on what you have done many times in the past. You simply know the answer without having to know the reasons for it.

Questions not based in reality border on, and sometimes are, 'trick questions'. I don't like trick questions and think they have no place on tests.

I respect your opinion but my own differs.

Its all a test, trick questions cause you to think and read between the lines.

FWIW, I am good at tests. The questions in question don't present a hindrance to me, but I know they really mess with others, that's why I don't like them. I never will like them, even if I am never successfully tricked by one.

FWIW that sounds pretty darn arrogant.

Testing should reflect a person's ability to perform in a given area. Testing should not be about who knows how to take tests better and who knows how to deal with trick questions.

I always looked at tests as tests and as such I don't expect them to be written to my own desires.

 

[iceworm]

Ok here we go again--let's see if I can get this to be a poll:

What happens to RPM when you have a 4 pole motor operating at 60Hz and 240 Volt and change it to a 6 Pole motor?

You have a formula sheet with the following formula on it--P=(f)(120)/RPM

Wouldn't concern me how the swap was made from 4pole to 6pole. That wasn't part of the question. With the context you have given (or lack of context) the question appears to be asking if one understands the relation between number of poles and nominal RPM - no more, no less.

My answer would have been, "RPM goes from 1800 (nominal) to 1200 (nominal). If the only 'correct' answer was, "Decreases", I'd likely have squawked.

ice

 

[RichB]

Thanks guys!!

What I take from this is that I could have worded the question better to get the idea across, which I will!

Appreciate the input!

Rich