Examples of the Short-Circuit - Page 1
Forum section: electronics / beginners

author: Jasonbit
author_rank: Regular Contributor
timestamp: June 11, 2019, 12:49:44 am
content: Hello,I am searching about the definition "short-circuit" and I found this article:https://www.elandcables.com/the-cable-lab/faqs/faq-what-is-fault-currentThe fault current is it the same short-circuit? (Remember, the english is not my native language).What this author want say when he writes "...double phase to ground, three phase to ground, phase to phase and three phase." How can occur a fault current between double phase to ground? Can anyone show me a diagram or another explication?Thanks

author: wraper
author_rank: Unknown
timestamp: June 11, 2019, 01:28:13 am
content: That description is only barely relevant for electronics, it basically describes mains wiring. Short circuit is when something fails in a way that there appears low resistance path where it shouldn't be normally. Say IC fails and there appears low resistance between some of it's terminals. Or insulation failure happens somewhere, whatever.

author: DDunfield
author_rank: Regular Contributor
timestamp: June 11, 2019, 11:33:04 am
content: I believe the name "short circuit" comes from the notion that the electricity is taking an undesired "shorter" path rather than going through the load.Note that this may not actually be a physically shorter path, just an undesired alternate path of low enough impedance that a significant portion of the electricity flowing is bypassing the load.As for the terminology in the article (North America power described, may differ in your area):Background information (simplified) -- Main electricity in NA is delivered in three main forms:Double phase - Two 120v AC signals 180 degrees out of phase between a ground-potential NEUTRAL wire and two HOT wires.This is how power is usually delivered to residential and non-industrial business.This can be used as a single 240v source, or as two ...Single phase - 120v AC between NEUTRAL and one HOT wire.This is almost always 1/2 of a Double Phase feed.Three phase - Three phases 120 degrees out of phase with each other (voltage depends on service)This is how power is usually delivered to large industrial business.Back to your article, my interpretation:"Phase to ground" means any HOT wire in a feed unintentionally connecting to ground."Double Phase" to ground means both of the HOT wires in a two-phase feed unintentionally connecting to ground."Three phase to ground" means multiple HOT wires in a three-phase feed unintentionally connecting to ground."phase to phase and three phase" means two or three HOT wires in a feed unintentionally connecting to each other.Examples where multiple phases could short at the same time (or close in time) are things like fire where insulation is burned off, submerged cables where the shielding gets compromised and all wires deteriorate together, concurrent physical damage (backhoe cuts the cable) etc.Dave

author: soldar
author_rank: Super Contributor
timestamp: June 11, 2019, 11:39:07 am
content: I think "double phase" is more correctly called "split phase".

author: DDunfield
author_rank: Regular Contributor
timestamp: June 11, 2019, 12:38:42 pm
content: Quote from: soldar on June 11, 2019, 11:39:07 amAgreed, I was just referencing the terminology from the indicated article. It's not really double phase, I don't think real two-phase power (90 degree offset) is used anymore (at least here, perhaps somewhere in the world).

author: rstofer
author_rank: Super Contributor
timestamp: June 11, 2019, 05:42:29 pm
content: I have never heard of, nor used, the term "double phase" and, rarely, "split phase". The common residential service is just 120/240V single phase. Everybody in the business will understand exactly what that means.

author: Nerull
author_rank: Frequent Contributor
timestamp: June 11, 2019, 06:35:34 pm
content: There are still a handful of places out there that use two phase.