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. Currentlimiting fuses overload protection ranges eaton. General of seri es devices from the load to the source ar e. This standard is a revision of american national standard specifications for distribution fuse disconnecting switches, fuse supports, and current limiting fuses, ansi c37. Evaluating selective coordination between currentlimiting. 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. Mv currentlimiting fuses are primarily used to protect transformers, motors and other loads. The easiest and fastest way to select and specify the right fuse. 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. Selective coordination selective coordination cooper bussmann. The upstream device is a current limiting fuse and has a letthru current of k. 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. A currentlimiting fuse is one that opens and clears a fault in less than 180 electrical. The coordinaide protection and coordination assistant software lets you quickly and easily select the optimal protective device e.
Current limiting protective devices and its effects on. 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. Backup currentlimiting fuses, such as the 38kv transguard os shorty fuse, clear. Optimized overcurrent protection for padmounted, liquid. Evaluating selective coordination between currentlimiting fuses and non currentlimiting circuit breakers steve hansen senior field engineer robert lyons jr. 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. Due to different specifications of rated current the recommended continuous current of the fuse links is max. Lpcc, nonindicating, rejection, 15 a, 600 vac150 vdc, 20020 ka interrupt, class. Intelligent building software is a growing market segment as commercial building owners and managers adopt new. Backup currentlimiting fuse reduces risk of transformer. Currentlimiting fuses ieee conferences, publications. What are the pros and cons of current limiting fuses versus boric. Note that t m is the melting time of the fuse and t c is the total clearing time. 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.
Currently i have a protective device that is rated for 35k, but my bus fault is at 61k. What are the pros and cons of current limiting fuses versus boric acid fuses. Transformer components type k current limiting fuse canister. Please note that requesting information will automatically send us the results of our current fuse. Fuses the internal parts of modern currentlimiting fuses do not require maintenance. Lpcc, nonindicating, rejection, 10 a, 600 vac150 vdc, 20020 ka interrupt, class. Power overloads are like bouncing a check, and fuses respond to overdraws accordingly, protecting the system and keeping it balanced.
The type k canister allows the operator easy access to the current limiting fuse for inspection or replacement. 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. Dc arc flash and arcfault are offered as a separate modules. 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. Based on proper user input of transformer specification data, results will be a recommendation of properly coordinated eaton cooper power series transformer protection. Ecoord fuse and breaker coordination elite software.
A new version of the coordinaide protection and coordination assistant software is now available for use. 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. Current limiting class cc 95 items edison fuse, hclr series, class cc, current limiting, fastacting, 0. Examples are provided explaining the fuse graphs of a current limiting fuse. 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. Currentlimiting power fuses are manufactured in ratings. Both the minimum melting time and the total clearing time curves shall be shown on the fuse to fuse coordination graph. Evaluating selective coordination between currentlimiting fuses and non current limiting circuit breakers steve hansen senior field engineer robert lyons jr. Eatons current limiting medium voltage power fuse line. Its low cost and its limiting characteristics, which significantly reduce current amplitude and the energy released in the. Selective coordination of overcurrent protective devices is required by the. The links below open the online selector tools for bussmann series low voltage and medium voltage fuses.
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. Power fuses are like overdraft protection on checking accounts. Timecurrent curves fuses 800 a fuse rating what would cause a fuse to blow. Oct 01, 2007 within its current limiting range, a current limiting device is designed to interrupt all currents. 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. Currentlimiting fuses on the other hand, because of their construction, are inherently susceptible to element.
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. Automationdirect s covid19 related supply chain update currently shows we have our normal high levels of product inventory. Using currentlimiting fuses to increase short circuit. Hitech current limiting fuses cable accessories and. Any or all of these parameters may be entered to narrow the search results. 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. Based on proper user input of transformer specification data, results will be a recommendation of properly coordinated eaton cooper power. 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. Protection determined by comparing published values for letthrough for class cc, j, r, and t fuses versus a symmetrical rms waveform at 200ka. Select from the available attributes to find a fuses that meets your applications criteria. Rohs compliance selective coordination shortcircuit current ratings training. A common fuse myth is that it will blow as soon as the current flowing.
A new notification for transformer damage curve device indicates how other device tcc curves are affected. May 25, 2016 using current limiting devices to improve shortcircuit current rating sccr. Available fault current selective coordination spreadsheet. 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. The most common type of noncurrentlimiting fuse is the expulsion fuse other less. 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. Why arent current limiting fuses integrated in software modeling. 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. Home download center electrical software available fault current selective coordination spreadsheet.
Cc, 12 s response, ferrule terminal, holder mounting, cylindrical body, dual element. Fault tamer fuse limiters combine the functions of a conventional fuse cutout and a backup currentlimiting fuse in one powerful package which can. All relay, fuse and thermal element models are solved in timedomain with nonlinear functions, such as ct, vt and cvt magnetization. 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. Peak fuses current limiting fuses make achieving selective coordination easy and simple by maintaining a minimum amp ratio between upstream and downstream 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. Emphasis is given as to how proper coordination of each type of fuse with the transformer, and with each other, may. Eatons cooper power series transfusion coordination program is designed for use by electrical utility specification engineers, transformer designers and manufacturers, and electrical power consultants. Select an eaton current limiting power fuse to provide energy limiting fault protection for both indoor and outdoor medium voltage power distribution systems. 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.
Does not include current limiting circuit breakers or current limiting fuses. Time current curves fuses 800 a fuse rating what would cause a fuse to blow. Overcurrent coordination page 3 qualtech engineers, inc. Because a fuse is capable of interrupting a fault in its current limiting range in less than onehalf cycle i. Using currentlimiting devices to improve shortcircuit current rating sccr. Eaton completed development of a software program to allow. Fuses current limiting class cc at automation direct. Distribution transformer protection fuse coordination. Aug 12, 2016 dbl and dsl circuit breakers are a coordinated combination of breakers and current limiting power fuses. The total clearing time of the fuse should be use d for coordination purposes. The easiest and fastest way to select and specify the. Protect transformers against damaging overcurrents and. 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.
Ecoord fuse and breaker coordination huge builtin library of devices. The prearcing time limits indicate the relation of fusing time to current. Selective coordination fuse selectivity ratio guide figure 3 requirements for selective coordination. Using a commercial software package that plots the curves. 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. 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. What are the pros and cons of current limiting fuses. According to the nec, currentlimiting fuses reduce the current. Understanding current limit fuses and let through current. 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. 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. 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. Improving electrical safety using currentlimiting fuses. Bussmann series current limiting medium voltage fuse.
Its low cost and its limiting characteristics, which significantly reduce current amplitude and the energy released in. Do smaller fuses coordinate well with the systems other overcurrent. Understanding time current curves maverick technologies. 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. The transformer inrush current is also plotted as a single point on the tcc diagram.
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. Understanding current limit fuses and let through current duration. 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. Series coordination in easypower, relay coordination time intervals. 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. Protective device coordination protective device coordination study description. Its essential component is a metal wire or strip that melts when too much current flows through it. 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. Current limiting class cc circuit protection fuses. In electronics and electrical engineering, a fuse is an electrical safety device that operates to provide overcurrent protection of an electrical circuit. Bussmann lowpeak time delay fuse, current limiting, series.
When applied to current limiting fuses, a currentlimiting fuse is one that opens and clears the current in less than. First over current protection is discussed and the tcc fuse melt chart is examined with examples. Ecoord gets the job done right when it comes to analyzing time current curves for overcurrent protection devices. 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. With modern currentlimiting fuses, selective coordination can be achieved by adhering. Consulting specifying engineer selectively coordinated. Current limiting protective devices and its effects on fault calculations question. Select from the available attributes to find a fuse s that meets. These differences in the unbalanced and 100% damage curves can. In the illustration below, you can see how a current limiting fuse provides overdraft protection for power. Low voltage breaker fuse coordination requires a minimum 0. 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. Current limiting class cc 95 items edison fuse, hclr series, class cc, currentlimiting, fastacting, 0. The purpose of the fuse is to provide current limiting to increase the short.
Evaluating selective coordination between current limiting fuses and non current limiting circuit breakers steve hansen senior field engineer robert lyons jr. An expulsion fuse is not current limiting and as a result limits the duration of a fault on the electrical system, not the magnitude. 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. In the united states they are known as class j, class l, class r, etc. There is no need to list all the advantages which make this device so successful. 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. Overcurrents an overcurrent is either an overload current or a shortcircuit current. Selective coordination using current limiting fuses. Protective device coordination analysis paktechpoint.
Im sorry maybe i dont know how to utilize the function, but i know how to choose current limiting fuses. 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. The bussmann series fuse selector tool is an online application that will help you select a bussmann series fuse based upon fuse characteristics. Currentlimiting fuses make achieving selective coordination easy and simple by maintaining a minimum amp ratio between upstream and downstream fuses. Please note that requesting information will automatically send us the results of our current fuse selection including all criteria entered. 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. Bussmann series fuse selector tools one web world class. Standards permit 10 percent current tolerance for fuse curves. Please confirm fuse amperage before ordering this item due to part number similarities. Selective coordination using currentlimiting fuses. A fuse will restrict fault currents to such low values that a high degree of protection is given to.
Before you can access or download any nocost software program. 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. Control engineering using currentlimiting devices to. Arc flash forum view topic current limiting fuses brainfiller.