How to use selective coordination in ptw skm software help desk. Guide to power system selective coordination 600v and below document number 0100db0603 2. Timecurrent curves to browse timecurrent curves select a product within the dropdown menu, and then click go to view a list of downloads for that product. The recently published nema abp 1 provides guidance to design professional engineers and authorities having jurisdiction ahj on how to comply with the 2008 national electrical code requirements for selective coordination for emergency circuits and legallyrequired standby systems articles 620, 700. Selective coordination faq skm powertools electrical. Selective coordination be abb industrial solutions. Overcurrent coordination page 3 qualtech engineers, inc. The selective coordination feature can be accessed and used in oneline drawings, tcc drawings timecurrent curve, and in the component editor. As this curve is reporting the amount of current vs time, it is aptly called. The most common approach for evaluating the race is to use special graphs known in the industry as time current curves tccs. Every circuit breaker has a characteristic curve that reports the. For fuse systems, verification of selective coordination is quick and easy. Popular methods of performing a selective coordination study currently three methods are most often used to perform a coordination study.
These curves are provided by the manufacturers of electrical overcurrent interrupting devices, such as fuses and circuit breakers. Overlays of time current curves, which utilize a light table and manufacturers published data, then hand plot on loglog paper. Curves is an instant software for setting the trip characteristics of the protection devices and verifying selectivity between abb circuitbreakers in low voltage. In fact, in many cases, breakers that do not appear to selectively coordinate based solely upon their individual curves do selectively coordinate in specific pairings. Display the time current curves of 1 to 8 circuitbreakers. Computer programs that utilize a pc and allow the designer to select timecurrent. One such method would be by comparing timecurrent curves tccs of. Electrical calculation tools schneider electric global. Automated selective coordination of circuit breakers youtube. Design of protection coordination of a distribution. In the past, prior to the adoption of selective coordination in articles 700 and 701 of the nec, selective coordination was required in nfpa 99 nec 517 systems for ground fault protection for a minimum of 6 cycles. If you purchase you have to look at software cost, subsrciption cost, time. Selective coordination is the ability to isolate an overcurrent condition in the.
Using specific software that provides tccs enables the engineer to be. Selective coordination what the inspector needs to know iaei. Doing so implies relying on the use of timecurrent curves tccs, but the information presented on tccs alone may be insufficient to determine selective coordination see the post selective coordination with molded case circuit breakers. In the past, engineers would construct these curves by. Often, its necessary to adjust system attributes to accommodate the selected devices. Curves allows the visualization of the time current, letthroughenergy and peak limitation characteristics of abb low voltage devices as well as cables and transformers.
Low voltage breaker fuse coordination requires a minimum 0. Selective coordination study recommended procedures. Available fault current selective coordination spreadsheet. How to use selective coordination in ptw knowledge base. That has since been removed, and nec 700701 are now recognized by both nfpa 99 and nec 517 as requiring full. Selective coordination tables published by the circuit breaker manufacturer indicate the maximum level of available fault current to which pairs of circuit breakers achieve selective coordination for all values of time even below 0. Jan 21, 2014 the time current curves of a device are important for engineers to understand because they graphically show the response of the device to various levels overcurrent.
The curves allow the power systems engineer to graphically represent the selective coordination of overcurrent devices in an electrical system. In the past, engineers would construct these curves by hand. Draganddrop layout, maintaining all the easypower oneline features. The curves must be analyzed and interpreted properly in relation to. The selective coordination feature can be accessed and used in oneline drawings, tcc drawings time current curve, and in the component editor.
Selective coordination can be done by employing several methods. Inst instantaneous gf ground fault gfd ground fault delay l s i g timecurrent curves circuit breakers cargill electrical team meeting 22. As mentioned previously, selective coordination is not required for healthcare per nec 2014. Control engineering understanding time current curves. Time current curves are not required for verification of selective coordination. Consulting specifying engineer selective coordination. Selective coordination is a design requirement newly added by both the 2005 and 2008 national electrical code to article 700 emergency systems see 700.
While going through my offices old files, i found a excel file where previous employees 1015 years ago draw tcc curves of some relays. Jan 28, 2014 a time current curve tcc plots the interrupting time of an overcurrent device based on a given current level. Selective coordination tools and spreadsheets part one. It is much like a race between protective devices to see which will interrupt first. Evaluating selective coordination between currentlimiting. Feel free to download the original worksheet and use it as a template for drafting your own selective coordination charts. The recently published nema abp 1 provides guidance to design professional engineers and authorities having jurisdiction ahj on how to comply with the 2008 national electrical code requirements for selective coordination for emergency circuits and legallyrequired standby systems articles 620. These curves are part of the product acceptance testing required by underwriters laboratories ul and. Loglog type graph paper is used to cover a w ide range of times and currents.
An organized timecurrent study of protective devices from the utility to a device. Selective coordination time current curve charts electric arc. Guide to power system selective coordination 600v and below. Reading and configuring timecurrent curves knowledge base. Relay relay coordination requires 1 that there be a minimum of 0. Relative to the 225 ampere feeder, coordination between primary and secondary fuses is not attainable, noted by overlap of curves.
Etap star protective device coordination software provides a plot options tool with all the necessary options to customize the display of the time current characteristic curve. Curves the abb software for trip characteristics coordination the. This type of separation of the curves should allow for selective coordination, assuming that the breakers circuit breaker. By using selective coordination time current curves. A schneider electric digital tool for breakertobreaker short circuit selective coordination. Search all the circuitbreakers that can be selective with a. Oneline diagram obtain the electrical system oneline diagram that identifies important system components, as given below. Using plot options, it is possible to customize the display of the current and time axes, legend, grid, curve plotting colors and properties, and more. Devices must also be verified per their assembly placement and conductor allowance.
Every circuit breaker has a characteristic curve that reports the manner in which it trips. Relay curve file also attached the file in attachment. Electrical calculation tools is a set of 7 computer aided online tools designed to help you. For fuse systems, verification of selective coordination is quick and easy, merely adhere to fuse ampere rating ratios as indicated by the manufacturer. One such method would be by comparing time current curves tccs of the given protective devices see tccs explained. Time is plotted on the vertical axis an d current is plotted on the horizontal ax is of all time current characteristic curves. The purpose of long time settings is to allow a time based delay to elapse before tripping the circuit breaker for low level current faults. Completed time current characteristic curves coordination study. You can create selective coordination graphs in design master electrical to coordinate timecurrent curves for the circuit breakers in your. We always evaluate breakers in pairs for selective coordination, and only look at the curve to the left of the available fault current. The time current curves of a device are important for engineers to understand because they graphically show the response of the device to various levels overcurrent. Where more than one driving machine disconnecting means is supplied by a single feeder, the overcurrent protective devices in each disconnecting means shall be selectively coordinated with any other supply side overcurrent protective devices. Computer programs that utilize a pc and allow the design.
Time current curves can also be plotted and selective coordination for any particular application can be verified by using ms excel. Protective devices time current curves made easy protective devices have different tripping units for different types of electrical equipment. One line diagram of the power system in etap procedure. The time current characteristic curves of protective devices should not overlap if selective coordination is to be achieved, nor should the primary device of the transformer trip on inrush.
A time current curve tcc plots the interrupting time of an overcurrent device based on a given current level. To achieve selective coordination with low voltage circuit breakers, the general rule is that no overlap of time current curves including the unlatching time is permitted up to the available shortcircuit current. Characteristi c curves are arranged so that the area below and t o. If several protective devices are to interact effectively in a switchgear system, it is necessary to compare their tripping characteristics in order to evaluate their selectivity for the demands of. I couldnt figure out how they have manipulated required data. If you are an electrical engineer doing protective devices coordination on a daily basis than it makes sense to consider purchasimg a commercial software license. Go to star protection and coordination study toolbox and create tcc time current characteristics curve of cb4, cb5 and fuse1. Curves is an instant software for setting the trip characteristics of the protection devices and verifying selectivity between abb circuitbreakers in low voltage plants. Regardless of which method is used, a thorough understanding of time current characteristic curves of overcurrent protective devices is essential to provide a selectively coordinated system. To browse timecurrent curves select a product within the dropdown menu, and then click go to view a list of downloads for that product. However, other analytical techniques and high current testing have demonstrated that these two circuit breakers are selective to a much. Selective coordination tools and spreadsheets part two. Protective device coordination protective device coordination study description.
Includes integrating the shortcircuit current analysis at necessary points in the system, plots of timecurrent curves, yes no na and analysisinterpretation of the curves to ensure selective coordination is achieved. Ge energy industrial solutions ge overcurrent device. Overlays of timecurrent curves, which utilize a light table and manufacturers published data, then hand plot on loglog paper. If the curves on the left side of the available fault current do not overlap, the breakers selectively coordinate. Evaluating selective coordination between current limiting fuses and non current limiting circuit breakers steve hansen senior field engineer robert lyons jr. Properly engineered and installed selective coordination. Overload and short circuit protection for the 150 kva. Electrical calculation tools schneider electric singapore. Circuit breaker selective coordination tables duration. Automatically documents oneline configuration, switching conditions, protective devices, fault currents, and morewithout user input. Once defined, a selectively coordinated solution must be found between system devices according to manufacturer timecurrentcurves and selective coordination tables. Achieving selective coordination with lv circuit breakers. A protection coordination study will consist of time current curves tcc of all the electrical equipment, protective devices and large motors.
Introduction with the inclusion of new language in the 2005 national electrical code nec, the requirements for selective coordination of electrical power systems are, at present, more stringent than. White paper understanding time current curves 46 the next section of the curve moving up the time axis is the long time section. How to achieve selective coordination of circuit breakers eep. Computer programs allow the designer to select time current curves published by manufacturers and place curves of all ocpds of a circuit on one graph.
Thank you for your interest in selective coordination designer v1. However, simply plotting the curves does not prove selective coordination. Selective coordination study recommended procedures 14 the following steps are recommended when conducting a selective coordination study. The elite software ecoord program aids in the selective coordination of. Selective coordination for critical systems per the 2014 nec.
Frequently asked questions about selective coordination. Selective coordination study currently three methods are most often used to perform a coordination study. Selective coordination with circuit breakers iaei magazine. This is possible using the same principle that allows series rating of breakers dynamic impedance.
Selective coordination is generally achieved by using the following minimum recommended margins between device characteristics. Selective coordination analysis tool schneider electric usa. Transformers obtain the following data for protection and coordination infor. To achieve selective coordination with fuses, the fuse ratio tables must be employed. Selective coordination what the inspector needs to know. However, selective coordination of circuit breakers is a possibility. This easypower webinar, taught by satish shrestha at easypower, will cover the use of easypower to perform automated selective coordination of. This fault current must be calculated, and several programs can perform these. You have the option to start from the upstream device to find tested selectively coordinated combinations for the downstream device. Calculation tools for low voltage electrical network. The concept of selective coordination is pretty simple. To selectively coordinate, only the 20a breaker may trip under this fault this means that. Understanding time current curves maverick technologies.
Once defined, a selectively coordinated solution must be found between system devices according to manufacturer time current curves and selective coordination tables. The 100a cb has a std set at 6 cycles and the 800a cb has a std set at 24 cycles. Selective coordination requires that only circuit breaker one clear the fault. Home download center electrical software available fault current selective coordination spreadsheet. The protective equipment should be set to defend motors, cables and system gear from overlay as well as shortcircuit states. Once you select the device and press ok, the software will automatically associate that. Feel free to download the original worksheet and use it as a template for drafting your own selective coordination. When using the published fuse selectivity ratios, drawing time current curves is not necessary for any level of overcurrent. Mar 15, 2016 how selective coordination is accomplished. For analyzing fuse selective coordination for higher level fault currents see the next page, medium to high level fault currentsfuse coordination. The graph below has been created using excel charting tool.
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