This simple radial system will involve three separate time current curve studies, applicable to the three feeder branches shown. Frequently asked questions about selective coordination. We suggest noting on the panel schedule the siemens breaker suggested by the tool and calling for an equivalent product for other approved manufacturers. Our selective coordination lookup tables are quick and easy to use. As part of nfpa 70, the nec has special requirements for selective coordination in specific electrical systems to help assure system reliability.
Selective coordination is an important part of designing emergency electrical systems. Selective coordination is required for systems related to life safety as defined in the nec, and is achieved when an overcurrent on a circuit is interrupted and only the closest upstream device opens such that only the section of the electrical system with a problem is taken offline. To finally perform selective coordination, arc flash, and short circuit studies. What are the 7 important steps to perform an arc flash study. Consulting specifying engineer learning objectives demonstrate. A protection coordination study will consist of timecurrent 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. A selective coordination analysis is the next step. Discussion of study results and methods to improve system protection and coordination. The selective coordination feature can be accessed and used in oneline drawings, tcc.
Creating tccs with software is a very simple procedure, but achieving the desired level of coordination can be difficult. Selective coordination is a design requirement newly added by both the 2005 and 2008 national electrical code to article 700 emergency systems see 700. The proper localization of a fault condition to restrict outages to the equipment affected, accomplished by the. Resources for understanding nec selective coordination requirements, and tools and products for achieving a selectively coordinated electrical system. If software is used to perform the selective coordination study, input all. This tutorial teaches the design of a protection coordination scheme for a power distribution network using etap. Selective coordination is required for systems related to life safety as defined in the nec, and is achieved when an overcurrent on a circuit is interrupted and. Nov 28, 2018 selective coordination shall be selected by a licensed professional engineer or other qualified persons engaged primarily in the design, installation, or maintenance of electrical systems.
Home download center electrical software available fault current selective coordination spreadsheet. However, other analytical techniques and high current testing have demonstrated that these two circuit breakers are selective to a much higher value, at least 39,600a. However, if you are doing selective coordination studies occasionaly only, than spending money to purchase an expensive software program may not be feasible. Ge energy industrial solutions ge overcurrent device. You have the option to start from the upstream device to find tested selectively coordinated combinations for the downstream device. Selective coordination of overcurrent protective devices is required by the nec for a few building systems for a limited number of circuits that supply power to vital loads. These requirements will be discussed in a later section. Etap star tcc features are also demonstrated in it. Selective coordination equipment branch mike holts forum. Selective coordination study our company performs selective coordination studies on electrical systems and protective devices. How to achieve selective coordination of circuit breakers eep. Some jurisdictions have defined a time cutoff for selective coordination choosing a level other than total selective coordination without ahj approval is risky. Conclusion selective coordination is a key requirement for increasing system reliability and safety of critical systems. How to achieve selective coordination of circuit breakers.
Selective coordination tools and spreadsheets part two. Apr 19, 2011 just buying the software will not resolve your situation. Free to use, the selective coordination designer scd v1. Selective coordination assures that in the case of a fault in the electrical system, the protective device closer to the fault trips. Timecurrent curves can also be plotted and selective coordination for any particular application can be verified by using ms excel. The selective coordination analysis tool provides you with the ability to select combinations of circuit breakers that provide total selective coordination some in the industry refer to this as selectivity down to 0. Selective coordination equipment branch mike holts. Selective coordination for critical systems per the 2014. Oneline diagram obtain the electrical system oneline diagram that identifies important system components, as given below. Nov 02, 2016 frequently asked questions about selective coordination email 1963 0 tweet this is the last in a series of posts discussing the national electrical code nec requirements for selective coordination. For consulting and plant engineers, protective device coordination software is absolutely critical for ensuring personnel safety and maximizing system uptime. The goal of a protective device coordination study is to achieve an optimum balance between equipment protection and selective isolation that is consistent with the operating requirements of the overall power system. Selective coordination webcast are answered here by syed peeran, pe, phd, cdm smith, and rick reyburn, pe, jba consulting engineers.
Selective coordination of protective devices is desired everywhere, but it can get costly and that is the reason it is only required where the continued operation of electrical systems is a must. A protective device coordination study evaluates the effects of equipment failures and fault currents within a power system and analyzes the impacts on the system operation. The graph below has been created using excel charting tool. In this post i will address some frequently asked questions and misconceptions regarding means for achieving high levels of selective coordination with molded case circuit breakers mccbs q. Total system coordination with up stream mediumvoltage and primary protectiv e devices must also be incorporated. Overcurrent device lookup tables and system design guide. Selective coordination study recommended procedures. Skm system analysis software electrical engineering. Selective coordination is the protective device coordination between selected feeders in order to achieve perfect coordination between those feeders. This differs from traditional typical coordination and coordination studies that attempted. Enables coordination engineers to easily and efficiently. Selective coordination faq skm powertools electrical. Design of protection coordination of a distribution. Available fault current selective coordination spreadsheet.
Jun 28, 2018 this tutorial teaches the design of a protection coordination scheme for a power distribution network using etap. Transformers obtain the following data for protection and coordination infor. Data collection procedures are performed as per nec requirements, after which a comprehensive model of the system is developed on power systems software. As an electrical engineering company, our engineers perform protective device and selective coordination studies for threephase and singlephase electrical systems. Display the timecurrent curves of 1 to 8 circuitbreakers. This is possible using the same principle that allows series rating of breakers dynamic impedance. The proper localization of a fault condition to restrict outages to the equipment affected, accomplished by the choice of selective faultprotective devices. Guide to power system selective coordination 600v and below.
For fuse systems, verification of selective coordination is quick and easy, merely adhere to fuse ampere rating ratios as indicated by the manufacturer. Software means the computer software programs for which licensee is. Etap star overcurrent device protection and coordination evaluation software provides an intuitive and logical approach to timecurrent characteristic curve selectivity analysis. The scope of this tool encompasses only breakertobreaker short circuit selective coordination. Downloads application guides power systems study specs tutorial videos. To coordinate ocpd and cable we need to understand first how to read the circuit breakers timecurrent curve and the cables damage curve. Design of protection coordination of a distribution network. It should be noted that the study of timecurrent curves indicates performance during overload and lowlevel fault conditions. The cooridnation study determines the extent of overcurrent protective device coordination within an electrical system and provides an analysis of all possible operating scenarios which will be or have been influenced by the proposed or completed additions or changes to the subject system 1.
The higher values available with many overcurrent devices will be shown on the tables in this reference. How to use selective coordination in ptw skm software help desk. Etap star offers insight into troubleshooting false trips, relay misoperation, and miscoordination. Low voltage breaker fuse coordination requires a minimum 0. Once you select the device and press ok, the software will automatically. Transformer damage curves indicate when it will be damaged, thermally andor mechanically, under overcurrent conditions. However, selective coordination of circuit breakers is a possibility. Electrical system studies, arc flash and coordination analysis.
With one of the largest and most experienced teams in the industry, eaton offers a wide range of options, including short circuit, coordination, and arc flash studies, mitigation techniques, osha required electrical safety training, failure analysis and onsite. Selective coordination tools and spreadsheets part three. Just buying the software will not resolve your situation. Selective coordination shall be selected by a licensed professional engineer or other qualified persons engaged primarily in the design, installation, or maintenance of electrical systems. Eaton s portfolio of electrical studies and services are designed to help your system operate more reliably, efficiently and safely. How to use selective coordination in ptw knowledge base.
Selective coordination analysis tool schneider electric usa. For circuits supplying power to all other loads, selective coordination is a. Electrical calculation tools schneider electric global. Achieving total selective coordination may result in undesirable levels of arc flash energy verification of total selective coordination is difficult. It is my opinion that the specifying consultant the engineer of record must perform the selective coordination study to confirm the equipment specified selectively coordinates. Critical operations data systems overcurrent protective devices shall be selectively coordinated with all supplyside overcurrent protective devices. Selective coordination is often referred to simply as coordination. Methods of performing a selective coordination study currently three methods are most often used to perform a. The radial distribution system is the cheapest to build and is widely used in sparsely populated. Relay coordination study and analysis is performed to make sure that safety operation of the system are functioning correctly and to avoid the nuisance tripping, as protection is a major concern in any industry and they rely on protective devices for the same. To test the protection and coordination settings of this system by generating tccs.
Calculation tools for low voltage electrical network. Available fault current selective coordination siemens. If they want a calculation, such as the selective coordination study, then they are likely to require it to be prepared under the supervision of a licensed professional engineer. Selective coordination study recommended procedures 14 the following steps are recommended when conducting a selective coordination study. Electrical engineers use powertools to perform harmonic analysis, transient stability analysis, short circuit analysis, and to determine demand load, voltage drop, arcflash hazard analysis and protective device coordination. If software is used to perform the selective coordination study, input all the data in the system first and run a fault analysis. Selective coordination for critical systems per the 2014 nec.
Apr 06, 2011 presented by chuck nochumson and dave loucks. Lowvoltage protection is covered in detail by the coordination examples in appendix g. Provide a shortcircuit, component protection, flash hazard analysis, and selective coordination study for the electrical distribution system from all power sources normal and emergency down to the branch circuit overcurrent protective device and equipment. 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. Guide to power system selective coordination 600v and below document number 0100db0603 2. If the specified equipment is used for the project and not substituted, then all is good. The coordination marker is a line that can be added to the tcc to show the maximum level of selective coordination between a pair. This is where you will find useful information for coordination studies and determining selectivity between overcurrent devices. Groundfault coordination most of the concern about groundfault protection. Now, get the job done in no time with onetouch automation from smartpdc the revolutionary productivity tool from easypower.
National electrical code defines selective coordination. If there is an attempt to change the library device while this box is checked, the software will display the following warning dialog. Discussion of issues related to selective coordination and compliance. The siemens selective coordination tool is based on data for siemens circuit breakers that may or may not be similar to products by other manufacturers. The following sections explain how to evaluate whether overcurrent protective devices provide selective coordination for the full range of overcurrents.
Full compliance with the selective coordination requirements of the nec is mandatory in most jurisdictions. Jul 23, 2015 a protection coordination study will consist of timecurrent curves tcc of all the electrical equipment, protective devices and large motors. The label is a text block showing the actual value. Determines the protective device types, characteristics. According to the nec, selective coordination means that the fuse or circuit breaker closest to the fault opens up without opening up the fuse or the circuit breaker. It is important to note that the type of overcurrent. Coordination study is very critical since the interval of the clearing the fault and the start of burning of the cable is just a matter of second or split of a second. Electrical calculation tools is a set of 7 computer aided online tools designed to help you. Selective coordination with circuit breakers iaei magazine. Mar 15, 2016 if software is used to perform the selective coordination study, input all the data in the system first and run a fault analysis.
Overcurrent coordination page 3 qualtech engineers, inc. Thank you for your interest in selective coordination designer v1. You might check the project requirements more carefully. The selective coordination feature can be accessed and used in oneline drawings, tcc drawings timecurrent curve, and in the component editor. A schneider electric digital tool for breakertobreaker short circuit selective coordination.
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