What is Short circuit: Definition and 92 Discussions

A short circuit (sometimes abbreviated to short or s/c) is an electrical circuit that allows a current to travel along an unintended path with no or very low electrical impedance. This results in an excessive current flowing through the circuit.
The opposite of a short circuit is an "open circuit", which is an infinite resistance between two nodes.

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  1. B

    Engineering Calculate 3ph short circuit symmetrical fault, per unit method.

    Homework Statement Calculate the three-phase short-circuit fault currents flowing into all five busbars. Homework Equations MVA base = 150MVA All base voltages were set to the local busbar voltages. Formulas I have used can be seen in the attached photos. The Attempt at a...
  2. M

    Why an electromagnet doesn't makes a short circuit?

    How can you have a simple coil connected to a battery without having a short circuit in it? How do they make electromagnets that don't heat the battery? Thanks :)
  3. A

    Why is voltage 0 in a short circuit?

    We know that U=IR (ohm's law) in a short circuit, R goes to 0, I goes to infinity so the voltage goes to 0*∞ which is undefined! Why voltage is 0?
  4. B

    Resistor and Current Source in Parallel with Short Circuit?

    This circuit is really confusing me. I'm trying to find i using KVL and KCL. What's throwing me off is the short circuit effectively created by the inductor. I know that the whole circuit can't be short circuited because there is a current source that is preventing all of i from going through...
  5. B

    Engineering How Do Reactors Affect Short Circuit Current in a 3-Phase Power System?

    Homework Statement A 3-phase, 10KV, busbar of a power station is divided into three sections joined by two reactors as shown in Figure 1. Each section contains a synchronous generator and supplies a transmission line through a transformer. The parameters of generators, reactors and...
  6. JJBladester

    What happens in a short circuit situation (parallel)?

    Homework Statement What will be the current flowing theoretically through each resistor this short-circuit case? Homework Equations V=IR I=V/R R_{T}=\frac{1}{\frac{1}{R_{1}}+\frac{1}{R_{2}}+...\frac{1}{R_{N}}} For a closed loop, \sum I_{entering}=\sum I_{leaving} The...
  7. G

    Short Circuit Current, EMF, Internal Resistance

    Okay so I have conducted an experiment to find the internal resistance of a battery pack by gradient of a graph of voltage against current. All so far okay. I went on to find the EMF also, again all so far okay. Now I need the short circuit current, and I can't find any information anywhere...
  8. N

    I have few doubts regarding short circuit test of transformers.

    Hi, What does rated output in a transformer signify? Is power same(or almost same) on both sides? In short circuit test, we apply reduced voltage to HV winding so as to circulate rated current in HV. This will cause rated current to flow in LV. But as per definiton of rated current...
  9. S

    Question regarding voltage and current across a short circuit

    When a short circuit occurs, why won't the light bulb light up as well? Since the short circuit and the main branch where the lightbulb is are connected in parallel so won't the two have equal voltages and hence the bulb will light up (P=V^2/R)? Some people told me that its because the...
  10. O

    Conceptual short circuit diode / zero-bias base collector junction BJT question

    Why exactly is there zero current flowing through a diode when it is short circuited, given the presence of the barrier potential? My current understanding is that the drift current precisely balances the diffusion current. But if you take a diode and short it with a wire, wouldn't you then also...
  11. T

    Faulty lamp because it short circuit

    Homework Statement http://www.xtremepapers.com/papers/CIE/Cambridge%20International%20A%20and%20AS%20Level/Physics%20%289702%29/9702_s06_qp_2.pdf number 7aHomework Equations None reallyThe Attempt at a Solution The answer is that C is the faulty lamp because it short circuit. But how do I know...
  12. F

    Transformer Short Circuit Calc

    Ok I've read a lot of articles and seen a lot of different ways of calculating the short circuit current at the transformer terminals. So I'm going to apply my own intuition and see if I can arrive at the correct value if someone could please confirm my answer. 6.6kV/400V 3 Phase 10MVA...
  13. G

    Exploring the Effects of Short Circuits in Parallel Generators: A Case Study

    Hi guys, Kind of newbie in this forum, i would like to ask your opinion in the following issue. I have an application using one Generator (50Hz-400Volts) connected in parallel to the grid (50Hz-20kV) thru a step up transformer (Ynd, 0,4 to 20kV). I have performed a short circuit study for...
  14. S

    Voltmeters, transformers coil and short circuit

    A voltmeter must always be connected in parallel right? But when I have a transformer's secondary coil which is connected in series to it, then why is there a voltmeter reading? If i connect a battery in series with a voltmeter, the voltmeter reading will be the voltage of the battery right? So...
  15. G

    Can a neutral wire cause a short circuit when earthed and touched by a person?

    Can a short circuit occur when a neutral wire is earthed, example a man touches a bare neural wire with bare hands..? And is the effect different for alternating and direct current?
  16. B

    Engineering Multiple Resistors and Short Circuit

    Homework Statement This is more of a concept question rather than a HW problem, but I have two Circuits shown in the image attached. I am not really understanding how a short would affect resistance in these cases. 2. The attempt at a solution For figure 1 I am considering one of two...
  17. M

    How do I accurately measure short circuit photocurrent?

    In my phototelectrochemical setup I have a working electrode, reference electrode and a counter electrode . Now I need to measure the short circuit photocurrent so that I can calculate IPCE (incident photon to photocurrent efficiency). How will I measure this current ?
  18. R

    Equivalent resistance with possible short circuit

    Homework Statement Find the current flowing through the voltage source in mA. Assume Vs = 3.9 V and R = 8.3 kohm. Round off your answer to two decimal points. Homework Equations 1/R(equivalent) = 1/R1 + 1/R2 + ... I=V/R Kirchoff's voltage law The Attempt at a Solution I considered the 3...
  19. W

    Understanding Short Circuit Duty in the Grid

    Can someone explain what short circuit duty is? I see this a lot in my field but I don't know what it means. I see it in the context of new generation coming onto the grid and needing to interconnect to the current transmission system.
  20. I

    How can an uncharged capacitor work as a short circuit?

    My book says, initially, an uncharged capacitor acts as a short circuit and we eliminate any resistors in parallel with the capacitor. My question is, how can a capacitor be a short circuit if there is a gap between them? How does current go through a capacitor initially?
  21. S

    Engineering Vout & Short Circuit Output Current: Need Help!

    Homework Statement Here is the problem: http://img507.imageshack.us/img507/6488/unled2b.jpg What is the open circuit output voltage, Vout? Estimate the short circuit output current Can someone explain to me how to do these. Homework Equations Honestly... no idea. I know V=IR and all that...
  22. D

    Transformer short circuit test ?

    Hi guys, After doing some reading on transformers and reading solved examples there was one thing I couldn't quite figure out. There was a transformer with all the nominal data (10k/0.4k kV/kV, 100kVA), it said that they made a transformer short circuit test when one side is shortened and...
  23. O

    Engineering Open Voltage and Short Circuit

    Homework Statement So the first part is to find Voc in this circuit: So I did this: -10 + 1200*i1 + 3300*(i1 - i2) - 12 = 0 since i2 = 0 A, -22 + 4500*i1 = 0 i1 = 22/4500 A = 0.0049 A Then, for Voc: 3300*(i2 - i1) + Voc + 12 = 0 since i2 = 0 A, 3300*(−22/4500) + Voc + 12 = 0...
  24. O

    Engineering Thevenin Theorem - Open Voltage and Short Circuit Current

    Homework Statement Homework Equations Thevenin Theorem, Kirchoff's Voltage Law, mesh analysis The Attempt at a Solution I'm kind of confused as to how to approach this question as a whole because I'm getting put off from the two voltage sources. I was thinking that maybe I could use mesh...
  25. B

    Is There a Short Circuit in Your Diagram? How to Spot It!

    How do i find if there is a short circuit in the circuit diagrams. i am really confused. please help.
  26. T

    Source with short circuit, 0 potential difference?

    In an example in my book (Uni. physics), there's a circuit with emf = 12V, internal resistance, r = 2 Ohm, and no external resistance, R = 0, short circuit. What I don't get, is that it says that across the terminals, the potential difference between these points must be zero since there is no...
  27. N

    Engineering Trying to find the short circuit current

    Homework Statement i have a circuit like this https://www.physicsforums.com/attachment.php?attachmentid=26017&stc=1&d=1274949363 and i want to reduce it to thevenin's equivalent as seen from the terminals of R5 Homework Equations IF i short circuit the resistor R5 in order to find...
  28. L

    Power network short circuit current calc

    I have a power network, two parallel generators which feed 2 parallel delta-wye transformers with a bus tie inbetween, from 690V to 33kV. These two transformers feed a bus which a whole bunch of 33kV/690V DELTA-WYE transformers hang off for distribution. There was a fault the other day at the...
  29. M

    When do inductors act like a short circuit and when they dont?

    -My professor said that if i is constant through an inductor that V=0 through the formula V=L(dv/dt) . So if an inductor is in series with a voltage source it will act like a short circuit. But if the inductor is in series with a resistor and the voltage source the inductor will not act like a...
  30. L

    How Do You Calculate the Location of a Short in an Underground Cable?

    Homework Statement An underground telephone cable, consisting of a pair of wires, has suffered a short somewhere along its length (at point P in the Figure). The telephone cable is 4.00 km long, and in order to determine where the short is, a technician first measures the resistance between...
  31. J

    What is the Short Circuit Capacity for a 24 kW 3-Phase Generator?

    I have a 24 KW 3 phase 120/208 volt synchronous generator I bought from China and I am having trouble finding the available short circuit amps or the %Z rating. Is there a chart anyone is aware of for common short circuit capacities?
  32. G

    Solving a 1500 W Heater Short Circuit

    The problem is that a space heater develops a short circuit when to much current enters the circuit. The power supplied is 1500 W and the max current before short circuit is 15A. Firstly we have to calculate the resistance of the heater where I used P = I^2 R. But now we have to find the...
  33. L

    Transformer short circuit fault calculation clarification

    Hi, I'm trying to perform a short circuit fault calculation on this transformer and load I have when a 3 phase bolted short (worse case) occurs. The transformer specs are below: Z(transformer)=5%, Z(cable)= .00306 + j.0027, Delta/Star 6.6kV/400V I can understand calculating the short circuit...
  34. T

    Engineering Short Circuit, and open circuit question

    Homework Statement What is the difference between an open circuit and a short circuit? Open circuit has no current, so does that mean any resistor in series with it, has no current ,so it can be ignored for analysis( v=ir so 0 current means 0 V) for finding let's say the Thevenin...
  35. maverick280857

    Understanding the Short Circuit Characteristic of a Synchronous Generator

    Hi everyone Books mention the Open Circuit and Short Circuit tests on a synchronous generator in order to determine its synchronous impedance. One observes that the Short Circuit Characteristic (plot of short circuit armature current versus field current) is a straight line all the way...
  36. A

    Short Circuit Protection Diagrams

    Is there any Short circuit protection diagram designed for power supplies which the current doesn't drop below 1A? Can you show me any?
  37. M

    Battery short circuit electrodes question

    In battery, after finishing of its construction and positive & negative electrode creation, why we will need an external electrical lead (for example copper wires) for transmission of energy between two poles? Why no short circuit occurs between positive and negative electrodes through...
  38. N

    Question about my short circuit argument

    So I had an argument with a friend, more like a discussion where we disagreed. It led to some interesting questions, or at least they are to me. I made a simple electromagnet using a battery, a nail, and an insulated copper wire wrapped around the nail many times with the ends of the...
  39. O

    Short Circuit: What Happens and What Operates It

    what is short circuit and wat happens to different circuits when it occurs.wat operates it .
  40. A

    Engineering Resistor Failure: Is it Open or Short Circuit?

    The statement, "when a resistor fails, it will normally open." is true. But I don't understand: when a resistor fails, doesn't that mean that the resistor doesn't work? so doesn't that mean that resistance=0=short circuit?
  41. P

    Difference between a short circuit and a parallel circuit?

    What's the difference between a short circuit and a parallel circuit? In a short circuit, my teacher told me that no current will passs through the more resistive path. I doubt it. If this is wrong, then I could distinguish the difference and similarities between them. If not, I really need...
  42. H

    General physics: Someone please explain what a short circuit is

    General physics: Someone please explain what a "short circuit" is I am currently reading electricity and although I have read my textbooks well, I still don't understand what a "short circuit" is..thanks :cry:
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