Please note that requesting information will automatically send us the results of our current fuse. Evaluating selective coordination between currentlimiting fuses and non currentlimiting circuit breakers steve hansen senior field engineer robert lyons jr. Based on proper user input of transformer specification data, results will be a recommendation of properly coordinated eaton cooper power series transformer protection. Protective device coordination protective device coordination study description. Its low cost and its limiting characteristics, which significantly reduce current amplitude and the energy released in the. Peak fuses current limiting fuses make achieving selective coordination easy and simple by maintaining a minimum amp ratio between upstream and downstream fuses. Power overloads are like bouncing a check, and fuses respond to overdraws accordingly, protecting the system and keeping it balanced. Intelligent building software is a growing market segment as commercial building owners and managers adopt new. Time current curves fuses 800 a fuse rating what would cause a fuse to blow. Overcurrent coordination page 3 qualtech engineers, inc. The easiest and fastest way to select and specify the right fuse. Please note that requesting information will automatically send us the results of our current fuse selection including all criteria entered.
Optimized overcurrent protection for padmounted, liquid. Current limiting fuses are manufactured in such a way that under a highlevel fault, the fuse link will melt within the first halfcycle, limiting the amount of fault current in the system to i p, which is known as the letthrough current. A current limiting fuse is a fuse that, when its current responsive element is melted by a current within the fuses specified current limiting range, abruptly introduces a high resistance to reduce current magnitude and duration, resulting in subsequent current interruption. Using currentlimiting fuses to increase short circuit. Select from the available attributes to find a fuses that meets your applications criteria. Why arent current limiting fuses integrated in software modeling. What are the pros and cons of current limiting fuses versus boric acid fuses. The coordinaide protection and coordination assistant software lets you quickly and easily select the optimal protective device e. The prearcing time limits indicate the relation of fusing time to current. All relay, fuse and thermal element models are solved in timedomain with nonlinear functions, such as ct, vt and cvt magnetization. Lpcc, nonindicating, rejection, 15 a, 600 vac150 vdc, 20020 ka interrupt, class. Hitech industryleading brand of current limiting fuses with advanced designs to provide maximum protection in small, costefficient form factors to optimize value, reliability and reduce system lifecycle costs.
This standard is a revision of american national standard specifications for distribution fuse disconnecting switches, fuse supports, and current limiting fuses, ansi c37. Fuses the internal parts of modern currentlimiting fuses do not require maintenance. Bussmann series fuse selector tools one web world class. Timecurrent curves fuses 800 a fuse rating what would cause a fuse to blow. In this module from the littelfuse university electrical safety by design series, we learn that designing currentlimiting fuses into your. Using currentlimiting devices to improve shortcircuit current rating sccr. Hitech industryleading brand of currentlimiting fuses with advanced designs to provide maximum protection in small, costefficient form factors to optimize value, reliability and reduce system lifecycle costs. The typical pplication of a mvcf a device is to install a secondary current relay which controls the operation of controllable fuse actuator module which bypasses the current into a high speed current limiting fuse. May 25, 2016 using current limiting devices to improve shortcircuit current rating sccr. Standards permit 10 percent current tolerance for fuse curves. Selective coordination selective coordination cooper bussmann. What are the pros and cons of current limiting fuses versus boric. Please confirm fuse amperage before ordering this item due to part number similarities.
System coordination between the breaker and power fuse prevents equipment damage and fire hazards caused by extremely high fault currents upstream and downstream from the power source. The links below open the online selector tools for bussmann series low voltage and medium voltage fuses. Currentlimiting fuses overload protection ranges eaton. What are the pros and cons of current limiting fuses.
The program performs a search based upon electrical or electronic fuse, the voltage rating, ac or dc, timedelay or fastacting characteristics, and the amp range, fuse class, fuse family, fuse series, fuse body type, size and even application. Overcurrents an overcurrent is either an overload current or a shortcircuit current. Selective coordination of overcurrent protective devices is required by the. Now that you have an idea what selective coordination is and what impact it has on the reliability of an electrical distribution system to deliver power to the loads, lets focus on what maintenance needs to be performed on overcurrent protective devices. Im sorry maybe i dont know how to utilize the function, but i know how to choose current limiting fuses. Emphasis is given as to how proper coordination of each type of fuse with the transformer, and with each other, may.
Examples are provided explaining the fuse graphs of a current limiting fuse. An expulsion fuse is a vented fuse in which the expulsion effect of the gases produced by internal arcing, either alone or aided by other mechanisms, results in current interruption. Applying current limiting fuses with modern molded case circuit breakers. The transformer inrush current is also plotted as a single point on the tcc diagram. The expulsion fuse or mvi clears lowmagnitude currents, such as those caused by faults external to the transformer and highimpedance faults inside the transformer, which are generally below the minimum interrupting current rating of the currentlimiting fuse. Your questions answered more answers about using current limiting devices to improve shortcircuit current rating sccr, the topic of a may 18 webcast, are provided by speaker erik barnes.
Oct 01, 2007 within its current limiting range, a current limiting device is designed to interrupt all currents. A common fuse myth is that it will blow as soon as the current flowing. The arc flash analysis module also includes comprehensive single phase and three phase arc flash calculations as well as an invaluable arc flash analyzer tool to summarize results from the arc flash study. With modern currentlimiting fuses, selective coordination can be achieved by adhering. When applied to current limiting fuses, a currentlimiting fuse is one that opens and clears the current in less than. Current limiting protective devices and its effects on. Based on proper user input of transformer specification data, results will be a recommendation of properly coordinated eaton cooper power. Arc flash forum view topic current limiting fuses brainfiller. Understanding current limit fuses and let through current duration. Selective coordination fuse selectivity ratio guide figure 3 requirements for selective coordination. Evaluating selective coordination between currentlimiting fuses and non current limiting circuit breakers steve hansen senior field engineer robert lyons jr. The upstream device is a current limiting fuse and has a letthru current of k. Considered an essential business as defined by the cisa, we continue to fill customer orders in accordance with current rulings. Before you can access or download any nocost software program.
The most common type of noncurrentlimiting fuse is the expulsion fuse other less. Leach consultant, hitech fuses abstract this paper examines the ways that fuses are used to protect distribution transformers and the systems to which they are connected. Rohs compliance selective coordination shortcircuit current ratings training. Its essential component is a metal wire or strip that melts when too much current flows through it. If a protective device cuts off a shortcircuit current in less than onehalf cycle, before it reaches its total available and highly destructive value, the device is a current limiting device. Currently i have a protective device that is rated for 35k, but my bus fault is at 61k. In the united states they are known as class j, class l, class r, etc. Eatons current limiting medium voltage power fuse line. Do smaller fuses coordinate well with the systems other overcurrent. Available fault current selective coordination spreadsheet. This new implementation for emtp allows to achieve highest levels of accuracy for protection coordination and analysis of performance with highly accurate power system models. Mv currentlimiting fuses are primarily used to protect transformers, motors and other loads. Ecoord gets the job done right when it comes to analyzing time current curves for overcurrent protection devices.
The overload current is an excessive current relative to normal operating current, but one which is confined to the normal conductive paths provided by the conductors. Test conditions for a 300 ka interrupting rated fuse 16 selective coordination 26 exceptions in the code for applying supplemental ocpds 35 10 reasons why supplemental protectors are not allowed 39 rules for medium voltage currentlimiting fuses 40 rrated medium voltage fuses and motor circuits 41. Because a fuse is capable of interrupting a fault in its current limiting range in less than onehalf cycle i. The expulsion fuse or mvi clears lowmagnitude currents, such as those caused by faults external to the transformer and highimpedance faults inside the transformer, which are generally below the minimum interrupting current rating of the current limiting fuse.
Hitech current limiting fuses cable accessories and. Both the minimum melting time and the total clearing time curves shall be shown on the fuse to fuse coordination graph. Mv current limiting fuses are primarily used to protect transformers, motors and other loads. Backup current limiting fuses, such as the 38kv transguard os shorty fuse, clear. Ecoord fuse and breaker coordination elite software. The type k canister allows the operator easy access to the current limiting fuse for inspection or replacement.
Eaton completed development of a software program to allow. Using a commercial software package that plots the curves. Automationdirect s covid19 related supply chain update currently shows we have our normal high levels of product inventory. Evaluating selective coordination between currentlimiting. Lpcc, nonindicating, rejection, 10 a, 600 vac150 vdc, 20020 ka interrupt, class. A new version of the coordinaide protection and coordination assistant software is now available for use. Type k current limiting fuse canister technical information and installation guide description the canister is typically mounted on the front wall of a single or threephase distribution transformer. In the illustration below, you can see how a current limiting fuse provides overdraft protection for power. First over current protection is discussed and the tcc fuse melt chart is examined with examples. These online tools aid in the selection of bussmann series branch circuit, supplemental and photovoltaic low voltage fuse and medium voltage fuses medium voltage fuse. Backup currentlimiting fuse reduces risk of transformer. Due to different specifications of rated current the recommended continuous current of the fuse links is max. Identify and analyze high risk arc flash areas in your electrical power system with greater flexibility by simulating and evaluating various mitigation methods in your arc flash study. I intend to use a 4,000a current limiting fuse to be installed right after the load terminals of a power cb with a 75kaic rating in an existing switchboard there is no space available to install the clf at the line terminals of the breaker.
Again, as part of the initial design, the transformer inrush current must be to the left of the transformer primary fuse curve otherwise the fuse will open when the transformer is energized. Power fuses are like overdraft protection on checking accounts. General of seri es devices from the load to the source ar e where there are two or more series protective devices between the fault po int and the power supply, these devices must be coordinated to insure that the device nearest the fault point will operate first. There is no need to list all the advantages which make this device so successful. The program performs a search based upon electrical or electronic fuse, the voltage rating, ac or dc, timedelay or fastacting characteristics, and the amp range, fuse class, fuse family, fuse. Backup currentlimiting fuses, such as the 38kv transguard os shorty fuse, clear. Distribution transformer protection fuse coordination. Current limiting class cc circuit protection fuses. An expulsion fuse is not current limiting and as a result limits the duration of a fault on the electrical system, not the magnitude. Note that t m is the melting time of the fuse and t c is the total clearing time. Currentlimiting fuses are manufactured in such a way that under a highlevel fault, the fuse link will melt within the first halfcycle, limiting the amount of fault current in the system to i p, which is known as the letthrough current. Fault tamer fuse limiters combine the functions of a conventional fuse cutout and a backup current limiting fuse in one powerful package which can be easily incorporated in new or existing installations of 14.
Consulting specifying engineer selectively coordinated. The easiest and fastest way to select and specify the. Bussmann lowpeak time delay fuse, current limiting, series. Currentlimiting fuses ieee conferences, publications. Its low cost and its limiting characteristics, which significantly reduce current amplitude and the energy released in. Transformer components type k current limiting fuse canister. Select an eaton current limiting power fuse to provide energy limiting fault protection for both indoor and outdoor medium voltage power distribution systems. Select from the available attributes to find a fuse s that meets. Fault tamer fuse limiters combine the functions of a conventional fuse cutout and a backup currentlimiting fuse in one powerful package which can. Protective device coordination analysis paktechpoint. Currentlimiting power fuses are manufactured in ratings. With builtin data for over 2,000 individual devices already builtin, all you have to do is select the devices you want from the list and youre ready to go.
General of seri es devices from the load to the source ar e. Low voltage breaker fuse coordination requires a minimum 0. Eatons cooper power series transfusion coordination program is designed for use by electrical utility specification engineers, transformer designers and manufacturers, and electrical power consultants. Current limiting protective devices and its effects on fault calculations question. Aug 15, 2018 methods to improve selective coordination include, but are not limited to, increasing the withstand capabilities of the upstream lineside ocpds, changing the type of circuit breaker for example, from moldedcase type to iccb or lvpcb, selecting a current limiting type protective device, using fuses that do not overlap in the instantaneous. Fuses current limiting class cc at automation direct. Eaton s cooper power series current limiting fuses provide overload protection for all overhead, indoor and underground cable distribution systems and are used for transformer protection, capacitor protection and sectionalizing. A fuse will restrict fault currents to such low values that a high degree of protection is given to. By limiting the let through energy at the fault, properly applied currentlimiting fuses assist in limiting or preventing shortcircuit damage to busway, circuit breakers, switches, and other electrical components.
Improving electrical safety using currentlimiting fuses. Methods to improve selective coordination include, but are not limited to, increasing the withstand capabilities of the upstream lineside ocpds, changing the type of circuit breaker for example, from moldedcase type to iccb or lvpcb, selecting a currentlimitingtype protective device, using fuses that do not overlap in the instantaneous. Home download center electrical software available fault current selective coordination spreadsheet. Current limiting is the practice in electrical or electronic circuits of imposing an upper limit on the current that may be delivered to a load with the purpose of protecting the circuit generating or transmitting the current from harmful effects due to a shortcircuit or similar problem in the load. Protect transformers against damaging overcurrents and. Dc arc flash and arcfault are offered as a separate modules.
They have become integral parts of many distribution systems because of their desirable characteristics of noiseless interruption, no expulsion violence, current. Using published ratio tables eliminates the need for selective coordination studies and ensures the affected circuits are isolated and. According to the nec, currentlimiting fuses reduce the current. Series coordination in easypower, relay coordination time intervals. Does not include current limiting circuit breakers or current limiting fuses. The problem is the software calculating the affects of those such fuses, for example at 30cycles the fuse should be clearly melted and there should be 0 current through the device. Understanding current limit fuses and let through current.
Fault tamer fuse limiters combine the functions of a conventional fuse cutout and a backup currentlimiting fuse in one powerful package which can be easily incorporated in new or existing installations of 14. A fuse may coordinate on one fault, but if the minimum melting curve has been crossed, the fuse may not coordinate on the next fault. Bussmann series current limiting medium voltage fuse. Currentlimiting fuses make achieving selective coordination easy and simple by maintaining a minimum amp ratio between upstream and downstream fuses. Currentlimiting fuses on the other hand, because of their construction, are inherently susceptible to element. Current limiting class cc 95 items edison fuse, hclr series, class cc, current limiting, fastacting, 0. These differences in the unbalanced and 100% damage curves can. A currentlimiting fuse is one that opens and clears a fault in less than 180 electrical. Etap ac arc flash analysis software brings you new and enhanced capabilities which allow for faster and easier assessment of arc flash hazards and incident analysis. The bussmann series fuse selector tool is an online application that will help you select a bussmann series fuse based upon fuse characteristics.
Your questions answered more answers about using currentlimiting devices to improve shortcircuit current rating sccr, the topic of a may 18 webcast, are provided by speaker erik barnes. Ecoord fuse and breaker coordination huge builtin library of devices. The purpose of the fuse is to provide current limiting to increase the short. Selective coordination using current limiting fuses. Current limiting class cc 95 items edison fuse, hclr series, class cc, currentlimiting, fastacting, 0. Evaluating selective coordination between current limiting fuses and non current limiting circuit breakers steve hansen senior field engineer robert lyons jr. Selective coordination using currentlimiting fuses.
In electronics and electrical engineering, a fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. A new notification for transformer damage curve device indicates how other device tcc curves are affected. Understanding time current curves maverick technologies. Control engineering using currentlimiting devices to. Any or all of these parameters may be entered to narrow the search results. The total clearing time of the fuse should be use d for coordination purposes. Protection determined by comparing published values for letthrough for class cc, j, r, and t fuses versus a symmetrical rms waveform at 200ka.
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