Complex Imaginary, Question Five, CI 5. - Electrical - Engineer Boards
Jump to content
Engineer Boards
Sign in to follow this  

Complex Imaginary, Question Five, CI 5.

Recommended Posts

Hello All,

A little help would be appreciated on this one.  In the Complex Imaginary Test, Morning Session, Question 5 (the one through iBooks) the question asks about the fault current after a switch is thrown.  The circuit shows an inductor on the source side of the switch.  I went to solve this problem believing that this should be an instantaneous switch (there is no indication components are not ideal) and the fault would also occur immediately following the switch being thrown.  I recalled form my basic college courses that current cannot change instantaneously in an inductor.  However the answer is given by way of circuit analysis including the downstream resistor.  Was this an improper assumption?98691794_question5amexam.png.3b911c8cf08807d4be17210bfc1ac748.png

Share this post

Link to post
Share on other sites

In case anyone else needs the solution...

IIRC, the current I1 is listed in the problem, before the switch is moved.


X1 = V / I1 = 1500 / I1

Then when the switch is moved:

Zeq = R1 + jX1

 I1 = V / Zeq

The only trick here is remembering that the calculated impedance of the inductor is a reactance. So, Zeq = R + jX, not Ze = R + X.

Share this post

Link to post
Share on other sites

Join the conversation

You can post now and register later. If you have an account, sign in now to post with your account.

Reply to this topic...

×   Pasted as rich text.   Paste as plain text instead

  Only 75 emoji are allowed.

×   Your link has been automatically embedded.   Display as a link instead

×   Your previous content has been restored.   Clear editor

×   You cannot paste images directly. Upload or insert images from URL.

Sign in to follow this  

  • Create New...