0
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
What else can I help you with?
How do you calculate appropriate circuit breaker in the circuit for ac voltages?
It is depending on : whether the ac power is 110 or 220 v , length of wire/cable from mains to CB(circuit breaker),diameter of wire/cable consumption of circuit ( How much watts the circuit consume) i.e load .. don't forget this relation I=V/R . where I= current (amps) , V=voltage & R= resistance also I=P/V where P is power in watts . note that less voltage or thinner wire may affect the real rating of CB
How long is the main ring?
If you are talking about an electrical ring main it can be as long as you want it as long as it returns back to the circuit breaker with the other end of the cable, which if you didn't return the 2nd end of the cable to the circuit breaker you would have a radial circuit.
What is the starting current of 315 kw 380v motor..pf of .80 percent 3 phase..and what is the circuit breaker to use..sub breaker and main breaker?
starting current of 315 kw motor in start delta 2.5 time for single sec. if your cable lingth 130 meter u can use 150mm2 (3 cable per phase) 150mm2 single cable current 292 Amp voltage drop 0.28/meters so u can use breaker 1000 Amp and set Im time (for starting current) setting avalible in breaker.
Cause of a circuit breaking tripping?
Tripping is caused by excessive current, which is usually the result of a fault in cable or equipment. The circuit breaker is there for safety and it trips to prevent a possible fire starting.
What is over current protaction?
'Overcurrent protection' is a means of protecting a cable and its load from damage due to an overcurrent. An 'overcurrent' is defined as either an 'overload current' (due to an excessive load) or a 'short-circuit current'. In its simplest form, overcurrent protection is provided by means of a fuse, but it can also be provided by means of a circuit breaker. In the case of high-voltage systems, the circuit breaker is tripped by the operation of one or more overcurrent protection relays which monitor the circuit using current transformers.
A small appliance circuit will be protected by a circuit breaker rated at?
Yes, it will be protected by a circuit breaker or fuse. The normal rating of the circuit breaker or fuse is 25% more than the maximum current expected, or the maximum current allowed for the cable size, whichever is lower.
Is there a circuit breaker that is operated by a signal sent down the same cable that's supplying power to it?
yes it is the main breaker
What is the testing procedure for an earth leakage circuit breaker?
You can test this breaker by clamping it onto the earth cable. This will provide you with the measurements that you need.
Where is the motor relay circuit breaker located on a 1989 mustang?
The motor relay circuit breaker may be found on the driver's side of the vehicle, on or near the fender apron. There is a cable that runs from it to the battery.
What is the purpose of the black cable in this electrical circuit?
The purpose of the black cable in this electrical circuit is to carry the electric current from the power source to the connected devices or components in the circuit.
Why is it important to use the correct size cable and circuit breaker?
Because of resistance drop; if the cable is too long, you could be drawing additional amperage because of line loss (inductive load), or losing excessive power in the cable. Additionally, the gauge of the cable should be considered as well. If you are using a GFI circuit breaker, too long of a run can cause the GFI to continually pop because of inductance and line loss.
How do you calculate the size of cable according to current?
First determine the amperage of the circuit . e. g 15 amp or 20 amp ( typical household circuit ratings) the gauge is 14 and 12 respectively. The lower the gauge number the higher the current handling capability.
