questions on Power Factor

[dia480]

What are the typical questions on a Masters regarding Power Factor?

 

[Ed MacLaren]

Re: questions on Power Factor

Here are some sample questions from our equivalent exam in Canada, the Interprovincial.

1. Calculate the power factor of a 10 HP, 460 volt, 14 amp, three phase motor at full load, if it's efficiency is 86%. ___________%.


2. Determine the full load current drawn by a 2 HP, 230 volt, single phase motor, operating with an efficiency of 80%, and a power factor of 67%. __________amps.


3. A 480 volt, three phase feeder is supplying a load of 38.4 kilowatts at 80% power factor. Calculate the reactive power. _________kilovars.

Ed

[ June 08, 2003, 01:27 PM: Message edited by: Ed MacLaren ]

 

[bphgravity]

Re: questions on Power Factor

Here are some more that I know have been seen on the EXPERIOR EXAM.

1. The power factor of an incandescent lighting circuit is:

a. 0 b. .5 c. .707 d. .866 e. 1.0

2. The phase relationship between voltage and current at a capacitor is the current:

a. leads the voltage by 45 degrees
b. is in phase with the voltage
c. leads the voltage by 90 degrees
d. lags the voltage by 90 degrees

3. Power factor is:

a. R/X
b. power/apparent power
c. the efficency
d. the ratio of current to in-phase current

Not all power factor calculations are mathematical in nature.

 

[tom baker]

Re: questions on Power Factor

Mike Holts exam prep has representative questions and has been highly recommended by those who have used it.
By the way, Washington State dropped Experior (they were bought out by Sylvan Learning Systems) as there were too many complaits, and the state electrical dept felt that Experior had no incentive for an applicant to pass the first time, retake=more money for Experior.

 

[bphgravity]

Re: questions on Power Factor

Originally posted by tom baker:
By the way, Washington State dropped Experior (they were bought out by Sylvan Learning Systems) as there were too many complaits, and the state electrical dept felt that Experior had no incentive for an applicant to pass the first time, retake=more money for Experior.

It is my understandiong that there are 19 counties in the state of Florida that has dropped local examination when Experior took over Block and Associates. I agree that Experior is in the business to sell a test and not assist in applicant qualifying.

However, what testing agency is really testing the applicant on their electrical abilities and not their testing abilities?

Here is a quote from the State of Florida Ulimited Certified Contractors Exam Application Form:

A person who is not familiar with electrical contracting and cannot use the N.E.C. will find it hard to guess the correct answer for any question because they present the candidate with a choice of common faults, incorrect practices, or plausible nonsense.

 

[tom baker]

Re: questions on Power Factor

Bphgravity, I agree on test taking. I had a college course on "instructional devices", ie test development. After this course I understood the methodolgy of test development and test taking....

 

[pam]

Re: questions on Power Factor

bphgravity...where in the code book are the answers to your questions..

thanks

 

[bphgravity]

Re: questions on Power Factor

They aren't. This is basic electrical theory. Not all exam questions are derived directly form the NEC.

 

[pierre]

Re: questions on Power Factor

Hello Pam

There are several different theory books (including Mike Holt's) available on the web, there are exellent websites available with this info also. Go to www.google.com and type in the search area what you are looking for, in this case you might type - Electrical theory.

Good Luck

Pierre