Neither parallel nor series

W

Wong

Guest
What theorem or method can be applied to calculate the total
resistance at point A to B?

----- A -----
| |
| |
R1 R2
| |
| |
------R3------
| |
| |
R4 R5
| |
| |
----- B -----

Thanks.
 
tatto0_2000@yahoo.com (Wong) wrote in message news:<509bfe22.0410192154.627939bb@posting.google.com>...
What theorem or method can be applied to calculate the total
resistance at point A to B?

----- A -----
| |
| |
R1 R2
| |
| |
------R3------
| |
| |
R4 R5
| |
| |
----- B -----

Thanks.
Click to expand...
Star to delta conversion will work here.

Your above star connection can be converted into equivalent delta
connection, like this



RB
___
|--------------|---|___|----------------|
| | | |
| | | |
| | | |
.-. .-.
B RA | | | | RC A
| | | |
| '-' '-' |
| | | |
| ___ | | ___ |
|----|___|-----|-----------|-----|___|--|

R5 R2

created by Andy´s ASCII-Circuit v1.24.140803 Beta www.tech-chat.de


RA = ( R4*R1 + R1*R3 + R3*R4 ) / R1

RB = ( R4*R1 + R1*R3 + R3*R4 ) / R3

RC = ( R4*R1 + R1*R3 + R3*R4 ) / R4


Now it is easy enough, for you to further simply it.
 
Use Delta to STAR conversion,


----- A -----
| | |
| Ra |
R1 | R2
| / \ |
| Rb Rc |
--/----R3----\-
| |
| |
R4 R5
| |
| |
----- B -----
Click to expand...
the result became, and it is series with parallel series.

A > | | |
Ra
|
/ \
Rb Rc
--/ \-
| |
| |
R4 R5
| |
| |
----- B -----
Click to expand...

Ra = (R1+R2)/(R1+R2+R3)
Rb = (R1+R3)/(R1+R2+R3)
Ra = (R2+R3)/(R1+R2+R3)


it is in Electrical technology by Edward Hughes

KM





tatto0_2000@yahoo.com (Wong) wrote in message news:<509bfe22.0410192154.627939bb@posting.google.com>...
What theorem or method can be applied to calculate the total
resistance at point A to B?

----- A -----
| |
| |
R1 R2
| |
| |
------R3------
| |
| |
R4 R5
| |
| |
----- B -----

Thanks.
Click to expand...
 
kianmeng.tey@gmail.com (KM) wrote in message news:<ecdf7787.0410200555.2e97365d@posting.google.com>...
Use Delta to STAR conversion,


----- A -----
| | |
| Ra |
R1 | R2
| / \ |
| Rb Rc |
--/----R3----\-
| |
| |
R4 R5
| |
| |
----- B -----

the result became, and it is series with parallel series.

A > | | |
Ra
|
/ \
Rb Rc
--/ \-
| |
| |
R4 R5
| |
| |
----- B -----


Ra = (R1+R2)/(R1+R2+R3)
Rb = (R1+R3)/(R1+R2+R3)
Ra = (R2+R3)/(R1+R2+R3)


it is in Electrical technology by Edward Hughes

KM
Click to expand...
I think there is a correction here, Ra should equal to
(R1*R2)/(R1+R2+R3) and Rb, Rc as well.
So the total resistance is (Ra + ((R4+Rb) || (R5+Rc)))
Let say, R1=1k, R2=2k, R3=3k, R4=4k and R5=5k. I will get the answer
of 2.9k and it is same with my simulation. Thanks !!
 
whoops, what an ugly mistake i did; feeling very shameful.
should be delta to star. really frustrating isn't it……should go and die somewhere.
 
John Popelish <jpopelish@rica.net> wrote in message news:<4177F050.DFBA105D@rica.net>...
Jack// ani wrote:


whoops, what an ugly mistake i did; feeling very shameful.
should be delta to star. really frustrating isn't it should go and
die somewhere.

If that is the biggest mistake you make this year,you are doing
Click to expand...
well i hope so.

better than most of us.
Click to expand...
thanks
 
tatto0_2000@yahoo.com (Wong) wrote in message news:<509bfe22.0410192154.627939bb@posting.google.com>...
What theorem or method can be applied to calculate the total
resistance at point A to B?

----- A -----
| |
| |
R1 R2
| |
| |
------R3------
| |
| |
R4 R5
| |
| |
----- B -----
Click to expand...

You forgot to say "I don't like doing my own homework, please
do it for me."


And the correlary: if this ISN'T a homework problem, you
should say so. It also would help if you mentioned what
you've tried so far, and whether you're an absolute beginner
or not.
 
kianmeng.tey@gmail.com (KM) wrote in message news:<ecdf7787.0410200555.2e97365d@posting.google.com>...
Use Delta to STAR conversion,


----- A -----
| | |
| Ra |
R1 | R2
| / \ |
| Rb Rc |
--/----R3----\-
| |
| |
R4 R5
| |
| |
----- B -----

the result became, and it is series with parallel series.

A > | | |
Ra
|
/ \
Rb Rc
--/ \-
| |
| |
R4 R5
| |
| |
----- B -----


Ra = (R1+R2)/(R1+R2+R3)
Rb = (R1+R3)/(R1+R2+R3)
Ra = (R2+R3)/(R1+R2+R3)
Click to expand...
I'm not following these formulas.
If all the resistors R1-R5 are 1 ohm, then the
total resistance from a to b will be 1 ohm.
But, according to the formulas, Ra, Rb ,Rc will
be 2/3 or 0.67 ohms. So, we have 1.67 in parallel
with 1.67 which is 0.83 which is in series with
Ra (0.67). That all adds up to 1.5 ohms, but it
should be 1 ohm.

What am I missing?


-Bill
 
You must log in or register to reply here.

Welcome to EDABoard.com

Sponsor

Back
Top