Previous in Forum: load angle and power angle   Next in Forum: NOX reading if fluctuating in SIEMENS ULTRAMAT 23
Close

Comments Format:






Change Mode
Close

Subscribe to Discussion:

CR4 allows you to "subscribe" to a discussion
so that you can be notified of new comments to
the discussion via email.

Close

Rating Vote:







Add Vote
5 comments
Rate Comments: Nested
yousef harb
Member

Join Date: Mar 2010
Posts: 7

voltage drop

03/06/2010 1:35 AM

Ineed an example of how to calculate voltage drop on (MV) a 380 Volt system
Register to Reply
Interested in this topic? By joining CR4 you can "subscribe" to
this discussion and receive notification when new comments are added.

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
redfred
Guru
Engineering Fields - Electrical Engineering - Been there, done that. Engineering Fields - Control Engineering - New Member

Join Date: Dec 2008
Location: Long Island NY
Posts: 15600
Good Answers: 981
#1

Re: voltage drop

03/06/2010 11:58 AM

Simple just follow Kirchhoff's laws, combined with Ohm's laws. Once you have a good grasp of these two laws you can tackle the rest of network theory including the Laplace transform, rules of superposition to even understand even transmission lines. You could try it the hard way by starting with Maxwell's equations for electromagnetics and derive the rest.

__________________
 "Don't disturb my circles." translation of Archimedes last words
Register to Reply
4
msamad
Guru

Join Date: Feb 2009
Location: Houston, USA
Posts: 946
Good Answers: 244
#2
In reply to #1

Re: voltage drop

03/06/2010 1:06 PM

Use this simple formula:

Ignoring the reactance:

Single phase system: Voltage Drop = 2 x I x R x L

Three phase system: Voltage Drop = 1.732 x I x R x L

Considering reactance:

Single phase system: Voltage Drop = 2 x I x (Rcosφ + Xsinφ) x L

Three phase system: Voltage Drop = 1.732 x I x (Rcosφ + Xsinφ) x L

Where,

I - Current through the conductor

R - Resistance (in ohm) of the conductor per KM

L - Length of conductor in KM

X - Reactance (in ohm) of the conductor per KM

φ – Load power factor angle

The value R and X are obtained from cable manufacturer (or standard data can be used).

Voltage drop is generally calculated as % of the system voltage. After you calculate the voltage drop, use this formula for % drop:

% voltage drop: (Voltage Drop x 100) / System voltage

- MS

__________________
 "All my technical advices in this forum must be consulted with and approved by a local registered professional engineer before implementation" - Mohammed Samad (Linkedin Profile: http://www.linkedin.com/in/msamad)
Register to Reply Good Answer (Score 4)
No more Good Answers. Go to first "Almost" Good Answer
lazzarus
Member

Join Date: Apr 2010
Posts: 9
#3
In reply to #2

Re: voltage drop

04/16/2010 6:17 AM

"X" is impedance, not resistance, better to use specific volt drop from cable supplier parameters mV/A/m for volt drops calculations.

__________________
 lazzarus
Register to Reply
wareagle
Guru
United States - Member - New Member

Join Date: Jun 2008
Location: Alabama
Posts: 1604
Good Answers: 63
#4

Re: voltage drop

04/16/2010 6:12 PM

Quote lazzrus "X" is impedance, not resistance, better to use specific volt drop from cable supplier parameters mV/A/m for volt drops calculations."

X is reactance. Impedance is generally defined as Z² = R² + X². Better check those books again.
Register to Reply
lazzarus
Member

Join Date: Apr 2010
Posts: 9
#5
In reply to #4

Re: voltage drop

04/16/2010 7:00 PM

My mistake thanks,

Z=R+jX, exactly

__________________
 lazzarus
Register to Reply Score 1 for Good Answer
No more "Almost" Good Answers.
Register to Reply
Have a Different Question?
5 comments

Good Answers:

These comments received enough positive votes to make them "good answers".

"Almost" Good Answers:

Check out these comments that don't yet have enough votes to be "official" good answers and, if you agree with them, vote them!
Copy to Clipboard

Users who posted comments:

lazzarus (2); msamad (1); redfred (1); wareagle (1)

Previous in Forum: load angle and power angle   Next in Forum: NOX reading if fluctuating in SIEMENS ULTRAMAT 23

Advertisement

Got Something to Say?
Ask a Question
Start a Discussion

Search this Forum
Electrical Engineering:
Go

CR4 Sections
Aerospace
BioMech & BioMed
Chemical & Material Science
Civil Engineering
Communications & Electronics
Education and Engineering Careers
Electrical Engineering
General Discussion
Instrumentation
Manufacturing
Mechanical Engineering
New Technologies & Research
Software & Programming
Sustainable Engineering
Transportation

Site Directories
Forum Directory
Blog Directory
User Group Directory
RSS Feeds

CR4 Rules of Conduct
CR4 FAQ
Site Glossary

Who's Online (75 right now)
Show Members
Advertisement