Shortcircuitanalytic sca software performs available fault currents calculations in threephase electric power systems you are working with. When you apply these requirements to a circuit breaker, you must calculate the maximum 3phase fault current the breaker will be required to interrupt. Calculations in full compliance with ansi, nema and ul requirements, ensuring the most accurate and safe equipment duty comparisons. When a fault such as a short circuit or current overload is detected by a protective relay, a trip impulse is sent to the circuit breaker. If the resistance was zero, then the calculated fault current would go to. The comprehensive fault follows a traditional ohms law calculation for fault current. Fault current calculations no transformer known afc this is the most common method and should be used in most projects.
Overstressed device alarms are displayed on the oneline diagram and included in short circuit analyzer and study reports. All the equipments should be rated to withstand this current. Calculation tools for low voltage electrical network. This amount of fault current varies based upon the source of power and where the shortcircuit condition is created. Sep 11, 2018 in this video, electrical fault level calculation for short circuit faults is shown. You will find sheet with very nice example already fulfilled. Apr 17, 2020 the process of locating a fault current will vary slightly, depending on the overall construction of the wiring system involved. Calculations in full compliance with iec requirements, ensuring the most accurate and safe equipment duty comparisons. Iec shortcircuit short circuit calculation software. Electrical calculation tools is a set of 7 computer aided online tools designed to help you. The ln fault current is higher than the ll fault current at the secondary terminals of a singlephase centertapped transformer.
Oct 21, 2019 the prospective shortcircuit current pscc is the maximum current that can flow through a shorted electrical circuit. He was a journeyman electrician, master electrician, and electrical contractor. Use this method when the utility provides the available fault current. Fast and easy analysis automatically delivered by the most advanced features in the industry. Fault current calculations are based on ohms law in which the current i equals the voltage v divided by the resistance r. Electrical calculation tools schneider electric global. Calculates the short circuit fault current level of a transformer on an infinite bus. Circuit breaker interrupting rating calculations pac basics. In 1974, mike realized there was a need for quality electrical training and opened mike holt. The amount of fault current that will be generated at your transformer and the amount of current that will enter the protective earthing system requires very careful calculations. The short circuit current at point 2 will be lower than point 1 due to the line impedance line impedance for the cables will impose the current the calculation below will show the short circuit current at point 2. How to calculate fault current in electrical substation.
A power system functions normally until after the occurrence of a fault in the system. Ansi shortcircuit short circuit calculation software. When there is a short circuit the resistance becomes very small, and that means the current becomes very large. After seeing this video, concept of fault level calculation for given single line diagram will be cleared. As discussed previously, fault current and shortcircuit current are interchangeable.
In more complex systems where the wiring is encased and may run. Example to calculate short circuit current for circuit breaker. From this, the maximum current during the fault can be deduced as. Fc2 mobile app quickly delivers fault current calculations in the palm of your hand. We use the cdegs engineering software from ses technologies. Calculate the shortcircuit current at the secondary of the transformer. Bussmanns fc2 calculator mobile and webbased application is a free tool that provides an easy means for calculating fault current levels and generating nec 110. Equipment intended to interrupt current at other than fault levels shall have an interrupting rating at nominal circuit voltage sufficient for the current that must be interrupted. For low voltage systems, the calculations are the same except for two items. Even if there is a utility transformer, most utilities will give you the fault current on the secondary side and you should use this method. Distribution transformer calculator free download and.
Etap short circuit software makes it easy to go from selecting elements, from the comprehensive library of short circuit current ratings, to performing dozens of different types of short circuit analysis. The circuit breaker must function as specified and interrupt the current as soon as possible or severe damage may occur. Home software fault analyses fault analyses fault analysis is an essential tool for the determination of shortcircuit currents that result from different fault phenomena, the estimation of fault locations, the identification of underrated equipment in electric power systems and the sizing of various system components. These faults are a challenge to clear as well, because of their high transient recovery voltage. In case of fault or short circuit when the value of current exceeds the circuit breaker current, it will automatically trip i. The good news is fault events can be minimized or avoided through diligent electrical design, accurate record keeping information on equipmentdevicesmotors. This tool can be used on the bussmann website or out in the field on a mobile device for those needing a quick and simple way to determine available fault current. Sample fault current calculations help contractors understand the source of power flow problems. The calculation of circuit breaker interrupting duty depends on how fast it can clear the fault, more specifically, from the time of short circuit initiation up to the time when breaker primary contacts part. Or if you have the available fault current, either given to you from utility, or if you are using this program to calculate fault currents at other parts of the system where the aic ampere interrupting capacity is known, input this number and it will automatically override the. Therefore, the circuits supply voltage and its impedance determine the pscc value. In normal conditions when the circuit current rating is lower than the circuit breaker rating, the circuit operation is normal and it can be changed by manual operation. What is the difference between a comprehensive study and a. Available fault current selective coordination spreadsheet.
To selectively coordinate, only the 20a breaker may trip under this fault this means that the next upstream device must not trip with 2500a of current prior to the 20a device opening. The volt drop, ac volt drop and dc volt drop are all calculated for fuse selection or motor fusing with a combination of ac voltage drop, dc voltage drop and series voltage drop. May 07, 2020 eatons bussmann series fc2 available fault current calculator application is an innovative tool developed for contractors, engineers, electricians, and electrical inspectors. Transformer short circuit fault current calculator jcalc. Ansi fault follows ansi c37 standards for calculating equipment ratings. With a simple system, it is sometimes possible to identify the origin of the problem by making a simple inspection of the wires that make up the system.
The edr is the best way to calculate wire gauge through voltage and fault current electrical calculators. The standard does allow some minor welding of the contacts to take place, so after a large fault it would still be necessary to inspect the breaker. Mike holt worked his way up through the electrical trade from apprentice electrician through electrical contractor, to become one of the most recognized experts in the world as it relates to electrical power installations. Short circuit calculation spreadsheet laobing kaisuo. Bussmann series fc2 calculatorfault current calculation. Short circuit analytic sca software and mobile apps perform available short circuit fault current calculations in threephase electric power systems you are working with.
Smartduty, an expert system included with shortcircuit, compares each equipment rating with the calculated fault duties, highlighting any problem areas on the oneline and providing a tabular report showing the equipment data, the available fault current, and the critical problem areas. Input the nameplate transformer impedance as a percentage, not a decimal i. Fault current, or shortcircuit current, that is the question. Short circuit calculation spreadsheet simple tool designed for data estimation and conservative shortcircuit scenarios.
These faults are difficult to detect by the overcurrent relay of the lineterminal circuit breaker, because the magnitude of the fault current is relatively low being limited by the impedance of the transformer. Display the time current curves of 1 to 8 circuit breakers. The bussmann series fc 2 available fault current calculator mobile and webbased application is a free tool that provides an easy means for calculating fault current levels and generating nec 110. The programs take into consideration all of the key electrical parameters of power distribution system including power supply, cables, transformers, motors and generators. Makes pointtopoint fault current calculations easy. Electrical formulas electrical training solutions mike. Knowing available fault current levels is vital for compliance with sccr requirements in nec and osha. Interactive simulation, with a simple mouse click, mimicking realworld breaker switching and shortcircuit results. See note under step 3 of basic pointtopoint calculation procedure. Calculation of size of transformer, fuse and circuit breaker. The 20a breaker is in a branch panel that has 2500a of available fault current.
Pscc is also known as available fault current or shortcircuit making current. Short circuit current calculations cooper industries. Calculate size of dol and stardelta starter components. As you can see, simplified short circuit fault calculations can be performed using a basic understanding of sources of fault power and current and impedance values that impede the short circuit power flow. Download32 is source for fault current calculation shareware, freeware download fault current calculator, popcalc pro calculator, design master electrical, powernet. Short circuit analysis short circuit software etap. Perform device duty calculations using etaps short circuit analysis software which allows you to determine fault currents and automatically compare these values against manufacturer short circuit current ratings. Medium and highvoltage circuit breaker rated cycle. The intent is to prove that the amount of fault current available to all panels in the new building, or to any new panel in an existing building, is lower than the fault current rating of the panels and lower than the fault current ratings of the breakers installed in the panels. Analyzers, plots and reports allow for quick determination of the worstcase fault current device duty. To calculate the fault current in a system it is first necessary to calculate the mva during a fault. The fault level should be calculated every five years and after any.