[RE-wrenches] voltag drop

Exeltech exeltech at yahoo.com
Mon Dec 8 15:05:20 PST 2008



Hello Jason,



The correct voltage-drop calculation requires round-trip distance.  Two
conductors, each the same gauge and carrying the same current will have equal
voltage drop.



For example:



                                    
Conductor # 1

           -----------------------------------------------------------------

          
|                                                              
|

  Power
Source                                          
      Load

          
|                                                              
|

         
-----------------------------------------------------------------

                                     
Conductor # 2





The equivalent resistive circuit:

                                    
Resistor # 1

           ----------------------------/\/\/\/\/\/\------------------------

          
|                                                              
|

  Power
Source                                          
      Load

          
|                                                              
|

          
----------------------------/\/\/\/\/\/\------------------------

                                     
Resistor # 2



Rather than get into the esoteric terminology (Thevenin's Theorem) .. suffice
to say the total of the voltage dropped across R1 + Load + R2 is equal to the
Power Source voltage, as is easily seen above.



Voltage is applied to the entire circuit.  It doesn't flow just "one
way".  The same is true of current, which also flows in the entire
loop.



Overall, "power" is generated by the Power Source, and
"consumed" in the Load, which makes us want to think of energy
flowing "one way".  Some of the power output by the Power Source
is lost in Resistors #1 and #2.  Even so .. the total energy dissipated by
R1 + Load + R2 must equal the energy delivered by the Power Source.



Hope this helps...



Dan

Sr. Engineer

Exeltech







--- On Mon, 12/8/08, Jason Lombard <openhandsolar at gmail.com>
wrote:

From: Jason Lombard
<openhandsolar at gmail.com>

Subject: Re: [RE-wrenches] voltag drop

To: "RE-wrenches" <re-wrenches at lists.re-wrenches.org>

Date: Monday, December 8, 2008, 4:44 PM

Marco,



One way it the appropriate answer, you mostly have voltage only going in that
direction is my thought.

On
Mon, Dec 8, 2008 at 3:12 PM, Marco <marco at pvthawaii.com> wrote:

I feel kinda
foolish in asking this.....but when calculating voltage drop in a conductor
over distance, do I use the one-way or round-trip distance?

 

thanks,

marco

 



Marco Mangelsdorf, Ph.D., President  

Electrical Contractor License
C-26351 

69 Railroad Avenue, Suite A-7 

Hilo, Hawaii 96720 USA 

(808) 969-3281, fax 934-7462

www.provisiontechnologies.com

 




      
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