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Lt cables has own impedance which reduce the short circuit fault level
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What is short circuit ratio?
Ratio of field current required to produce rated voltage in open circuit to the field current required to produce rated current in short circuit.
How is Fault level calculation computed?
The calculation of greatest fault current of system is required for calculation of the capacity of the switchgear or bus bar or cable. The source of the supply will be the consideration.The MVA/kVA capacity of the transformer or generator which is the source. The simple equation to find the short circuit current is 1.1 x V L I = --------------- Amps √ 3 x Z I - short circuit current Line voltage is multiplied by 1.1 to take care of 10% rise in voltage Z Impedance in ohms % Z x10 x kV 2 Z = --------------------- kVA Detailed calculation method is available in www. ecmweb.com You must read it if you are really interested to learn the subject. There are so much reading material on the subject in the net itself Similarly read this link http://books.google.co.in/books?id=yiT9Doq8TRwC&pg=PA184&lpg=PA184&dq=short+circuit+calculation+of+bus+bar+&source=web&ots=L1ww-bULxl&sig=Ker1LfRB8E9pWC5-fKnyNqPi_K0&hl=en#PPA184,M1
What is a circuit with no load?
An open circuit or a short-circuit (if that circuit is complete).
What is Short circuit maintenance current transformer in automatic voltage regulator?
the SCT is used to provide excitation during short circuit conditions. under Short Circuit the voltage may drop below threshold level causing field current to drop, to avoid over excitation by the AVR, the short circuit provides the excitation energy required to maintain a voltage that allows protective devices to operate and isolate the fault. the SCT is open under normal operating condition
Can different rating circuit breakers have the same short circuit characteristics?
Yes, different amperage rating circuit breakers can have the same short circuit characteristics.
What is short circuit ratio of an alternator?
Short circuit ratio is the ratio of field current required for the rated voltage at open circuit to the field current required for the rated armature current at short circuit
What is short circuit ratio?
Ratio of field current required to produce rated voltage in open circuit to the field current required to produce rated current in short circuit.
How does a circuit happen?
When the cables of the electrical appliances are worn out or it's not connected properly,a short circuit may occure.A short circuit has a very low resistance that almost all electric current flow through it.It'll affect the operation of the electrical appliances.Owing to the heating effect,the excess electric current would produce a large amount of heat,wihout a fuse or a circuit breaker,a fire may be occured when there's a short circuit.
How to calculate the short circuit current of circuit breaker or cable?
A short circuit study is required for that, modeling the electrical system. The short circuit current is also directly dependent on the location of the building system relative to the power grid and type of transformer bringing power into the building. For starters and keeping it "basic" look for Cooper Bussman's Point to Point Method of Short-Circuit Calculation. That is a good start and depending on what you need a good start. Remember to contact the utility company for available fault current, type of voltage transformer, transformer impedance and size. If you want to get technical, get SKM's software (expensive though). With it you can go several steps further into short circuit analysis, selective coordination and finally arc-flash protection. Hope this helped. JP Ross, Professional Engineer
How is Fault level calculation computed?
The calculation of greatest fault current of system is required for calculation of the capacity of the switchgear or bus bar or cable. The source of the supply will be the consideration.The MVA/kVA capacity of the transformer or generator which is the source. The simple equation to find the short circuit current is 1.1 x V L I = --------------- Amps √ 3 x Z I - short circuit current Line voltage is multiplied by 1.1 to take care of 10% rise in voltage Z Impedance in ohms % Z x10 x kV 2 Z = --------------------- kVA Detailed calculation method is available in www. ecmweb.com You must read it if you are really interested to learn the subject. There are so much reading material on the subject in the net itself Similarly read this link http://books.google.co.in/books?id=yiT9Doq8TRwC&pg=PA184&lpg=PA184&dq=short+circuit+calculation+of+bus+bar+&source=web&ots=L1ww-bULxl&sig=Ker1LfRB8E9pWC5-fKnyNqPi_K0&hl=en#PPA184,M1
Define generator short circuit ratio?
Checked Stephen J. Chapman's Electric Machinery Fundamentals page 287. It says: Short Circuit Ratio (SCR) for the synchronous generator is the ratio of the field current required for the rated voltage at OPEN circuit to the field current require for the rated armature current at SHORT circuit.
When you will get to know that short circuit will happen?
1. That if a short circuit occurs we will get a sign before short circuit will happen or not ? 2. what we can do ? 3. how fuse can get a short circuit ? 4. which wires we have to use from preventing short circuit ?
Why are resistances parallel to short circuits neglected in a circuit?
You can consider a short circuit to be a resistor with R=0 Ohms. It is then clear by the equation for calculation of parallel resistance that the combined resistance of a resistor in parallel to a short circuit is 0. Consider the following example with R1= 1k Ohms and R2= 0 Ohms: Rtotal = R1*R2 / (R1+R2) = R1*0 / R1 = 0 Ohms.
What is An example of a short circuit?
A short circuit is one that is characterized by extremely low resistance. This will result in the extremely dramatic increase of current. High current will flow until a safety device opens the circuit, or the weakest link in it burns out. And one of the two usually occurs in a moment or two.==Short Circuit happens when the cables of the electrical appliances are worn out or it's not connected properly,a short circuit may occure.A short circuit has a very low resistance that almost all electric current flow through it.It'll affect the operation of the electrical appliances.Owing to the heating effect,the excess electric current would produce a large amount of heat,wihout a fuse or a circuit breaker,a fire may be occured when there's a short circuit.
What happens in a circuit?
A short circuit is one that is characterized by extremely low resistance. This will result in the extremely dramatic increase of current. High current will flow until a safety device opens the circuit, or the weakest link in it burns out. And one of the two usually occurs in a moment or two.==Short Circuit happens when the cables of the electrical appliances are worn out or it's not connected properly,a short circuit may occure.A short circuit has a very low resistance that almost all electric current flow through it.It'll affect the operation of the electrical appliances.Owing to the heating effect,the excess electric current would produce a large amount of heat,wihout a fuse or a circuit breaker,a fire may be occured when there's a short circuit.
Is a megohm a short circuit?
No. A short circuit would be zero ohms.
Every short circuit is always a closed circuit while every closed circuit is not a short circuit?
Long winded but true.
