Examples are provided explaining the fuse graphs of a current limiting fuse. In other words, as the current increases, the pre-arcing time decreases. Time-current curves are typically shown on a log-log plot. 20 ms while if the current is around 225 A then it will take 50 ms to melt. TC%20curves 432×508 73.9 KB. Click the +/- accordions below to see the TCC Curves. The second part of the device is a coil wound around an armature where the circuit current flows through the coil. The melting time is considered nominal unless noted otherwise. JDL (Amp) 600V Current-Limiting Effects *Prosp. Time is shown on the vertical axis using a logarithmic scale and is plotted in seconds X 10X. … Fuse time/current curve. Let-Thru Current (Apparent RMS Symmetrical) S.C.C. For example, from Figure 1 it can be determined that a 20A MAXI Fuse experiencing an overload of 100A will open in about 0.5 seconds. The vertical axis represents the time, in seconds. Fuses 329 In preparing current-time characteristics it is necessary to choose a convenient basis of comparison so that the curves will show at a glance if discrimination is likely to be achieved. fuses now provide a visual open fuse indicator. With respect to … The curve indicates that 0.1 sec (6 cycles) the fault current that trip the fuse should be ~70kA. Following are the characteristics of TCCs: The over-current-time relay 1, HV HRC fuse D and trans- Keep in mind that the history of fuse temperature and ambient can determine fusing minimum time, so always plots show the fusing time at 25'C and not the … Typical time-delay or slow fuse time-current curves indicate the 10-millisecond current at 10 to 50 times the steady state current. Coordinaide lets you quickly and easily select the optimal protective device (e.g., … 1361 fuses and compare them. So only these values are required for compliance with the regs. SiNgLE LiNE DiAgrAm SHEET OF ADJuSTED VALuES TiTLE pAgE - FOLiO LiST Typically, Time Current Curves (TCC) of the circuit overcurrent protection devices is used. Fuses: information from the manufacturer’s time-current curves should be used. These curves may include both melting and total clearing time. If both are available, the total clearing time that represents the worst-case duration should be used. cuky2000 (Electrical) 10 Jan 20 15:30. The maximum clearing time (time it takes for breakers to completely open) decreases as current increases. These currents are estimates for how much current it takes to melt a wire in free air. Typically, Time Current Curves (TCC) of the circuit overcurrent protection devices is used. Curves apply for 60 Hz frequency and ambient temperatures from -20 C to 55 C. These curves are provided by the manufacturers of electrical overcurrent interrupting devices, such as fuses and circuit breakers. Curve for calculating the Melting Time of the fuse at target overload and respectively short-circuit current. Curves – User guide – pag 5 o Max Ik: Visualizes a vertical line at the maximum fault current of the current object. In transformers an I2t value is defined to show the thermal limits Time-current curves must be checked for fuses with different utilization category (e.g aM and gG), no overlapping shall be present. Current is shown on the horizontal axis using a logarithmic scale and is plotted as amps X 10X. continuous current of a 17.2kV 25A fuse 31.5 x .97 = 30.5A. For example, Littelfuse’s 383 series - TR5® time-lag 300V rated fuses have time-current characteristics as shown by the below graph. Making your time current curves (TCCs) look presentable in ETAP. As we can see, in the above graph, the high current tolerance is high when compared with the time in seconds. o Zoom out. The time required to blow out the fuse depends upon the magnitude of excessive current. Because if it's your first time looking at one of these, the chart they gave you is a hot mess... If the RMS Symmetrical available is greater than the point where the fuse characteristic curve intersects with the diagonal A-B line, then the fuse clearing time is 1⁄ 2 cycle or less. 10/09/2012 12:30 AM. The time current characteristic curves in Appendix 3 of BS7671:2001 are for protective devices used in consumer units.It is these devices which give shock protection (disconnection times) and Short circuit protection. 2 (a) shows the current-time characteristics of a device and its fuse where the device can be protected for all the values of overload currents. It will also provide a current against the entry of a specific time. For larger fault current in the range 70kA < Ifault < 100 kA the range of clearing time (arcing+ melting time) is: 0.1sec A fuse, which is designed according to a IEC standard, can continuously operate at 100% of rated current of the fuse. Fuse specs. Wide plot in instantaneous range shows fuse to be non-current limiting. Of course anything that helps dissipate heat, such as a heat sink, or concentrate the heat, such as insulation, will change the … S&C also offers Coordinaide™ — The S&C Protection and Coordination Assistant. Each line representing different current ratings of the fuse. This is because of the blow-apart contact design which utilizes the magnetic field built-up around the contacts. The rather unusual current rating assigned to SloFast fuse links is an 10 The standard requires a ratio limit of 1:1.6, which our fuses clearly exceed. TIME-CURRENT CURVE A time-current characteristic curve, for any specified fuse, is displayed as a continuous line representing the average melting time in seconds for a range of overcurrent conditions. Now that the basics of TCCs have been explained, a review of coordination is in order. In normal usage the fuse will not fail but as the current rises to high levels the fuse will fail in shorter times. Time-current curves are also used to compare fuses of the same series but of different current ratings. The selection of a fuse is done with the help of the current-time curves shown in Fig. Breaking Capacity. The manufacturer's time current curves are useful in determing the exact speed of a fuse for different overloads. 6. Shows the long-time fuse like characteristics. Comparison of the time current curve of 4 IEC fuse types 4. Why do fuse time current curves stop at 0.01 seconds or 6 cycles? The below image is showing the time vs. current curve of the above fuse. These curves may include both melting and total clearing time. 150% overload for 2 mins. 11.12. Reduction in the long time melting current of the fuses (approximately one hour and longer) due to higher ambient temperatures is the same as described above for “maximum continuous currents”. A time current curve (TCC) plots the interrupting time of an overcurrent device based on a given current level. Photovoltaic fuses gPV curve from 1 to 600 A, up to 1500 VDC How to choose the right fuse protection fusib_179_b_1_gb_cat ReCombiner box Level 2 + Fuse protection (10x38 ... gPV cylindrical fuses 14x51 Time/current operation characteristics 1A 2A 3A 4A 6A 8A 10A 12A 15/16A 20A 10000 100 1 1 10 100 1000 10x38 gP V Pr ear cing time (s) o Zoom in. The fuse rating is for Holding current and the A^2t (amp^2sec) is a thermal energy-related value to define the nominal Fusing current at 25'C ambient, which is defined by the curve, which starts around 40% above the holding value. JDL (Amp) 600V PEAK LET-THROUGH CURRENT CURVES Cat. Time-current characteristic curves are published at 25ºC. Not sure what you mean by … Time-Current Curves Circuit Breakers 17 . Note: both the current axis and time axis are logarithmic scale, which is the typical representation for OCPD time-current characteristics. This side of curve: Fuse element intact, no fuse damage Within this area fuse will be damaged but current may or may not be interrupted. 2. Graphs and curves can be annotated, labels moved, and values displayed. time-current curve. What is shown in figure 3 is the Current-Limitation curve for the Class J Dual-element Time-Delay fuse of a specific manufacturer. See, if the current flowing through the Fuse element is around 350 A then the Fuse element will melt in .02 sec i.e. In this example, the intersection is approximately 9500A; so for short-circuit currents above approximately 9500A, this KRP-C-800SP fuse is current-limiting. Grading of overcurrent-time relay and HV HRC fuse As an example of the power system shown in Fig. The total clearing curve is a plot of the longest melting time versus the current required to melt the fuse link. These curves may include both melting and total clearing time. 3. 7. COORDINATION OF FUSES Time Current Curves of Fuses, Current Limiting vs. The thing to remember is that you hit peak current in 1/4 cycle or about 4 ms with 60 Hz power. The calculator produces a time current curve characteristic plot for up to two curves and provides a clearance time against the entry of a specific current. This is the Current-Limitation curve for a class J dual-element time delay fuse. The melting time is considered nominal unless noted otherwise. TIME-CURRENT CURVE: The graphical presentation of the fusing characteristic, time-current curves are generally average curves which are presented as a design aid but are not generally considered part of the fuse specification. Trip Curves, aka Time Current Curves, can be an intimidating topic. Or, one can determine the wire diameter for a given material and fusing current so that a larger size wire can be selected to avoid fusing. Short Time … Time-Current Curves Circuit Breakers No action to left of curve Trip or clear on and to right of curve All devices should be considered at same voltage 18 . These graphs should be used by the engineer to detrmine the proper fuse size. While the magnetic region shows the response of the solenoid to fault current such as a short circuit current. Time-current characteristics are pre-sented graphically on standardized “log-log” paper. With advanced material technol-ogy added to the existing product the TR and TRS current limiting time delay fuses are engineered for overcurrent protection of motors and transformers, service entrance equipment, feeder and branch circuits. The crowbar circuit I’m familiar with is an electronic short-circuit across the … I'm trying to determine the time it takes for a fuse to blow, and both of these methods yield different results. These curves may vary by manufacturer; always make sure the document you are reviewing relates to the product you are applying. The violet curve is the switchgear main circuit breaker curve. The breaking capacity must be at least equal to the prospective short-circuit current that may occur at the point at which the fuse is installed. 88-3 fuses over the B.S. Concerning fuses of any type, many works show different models for expulsion fuses [6]- [8], current-limiting fuses [4], [9], [10] or even communication DC-circuits' fuses [11]- … To ensure that all the downstream and upstream protective devices are coordinated, current versus time (I versus t) curve is used which is also known as TCC or Time Current Curve. GES-6153 Mine Duty Molded-Case Circuit Breakers Types TE3 and TE13 Premium Duty Magnetic Trip Time-current. GES-6157 Mine Duty Type TK TK13 (300-1200A); Magnetic Trip Time-current Curves. Answer: The curve is a graph of the current against time. Why do fuse time current curves stop at 0.01 seconds or 6 cycles? quickly. S&C’s Time-Current Characteristic (TCC) Curves are available in Adobe® Acrobat® format as well as in Microsoft® Excel format for your use in other applications. Hence safe tripping is ensured with this fuse element. The capability curves for each category are shown in Appendix A and are discussed below. If both are available, the total clearing time that represents the worst-case duration should be used. Satisfactory discrimination time/prospective current curves between fuses and between an IDMTL relay and fuses in two alternative 11 kV/415 V radial connected circuits are shown in Fig. If a TCC curve is shown as a single line, most likely it is the total clearing time curve, or perhaps an average clearing time curve. Hi Mbrooke, It recognizes implicitly that any fuse does not provide protection in the overload range. Every circuit breaker has a characteristic curve that reports the manner in which it trips. Once the fuse has been selected, the time current curve must be checked against the actual pulse The period time (T) of this cyclic load example is 17mins Corresponds to cyclic pulse factor B=0.32 Find It from melting curve of the fuse for t=120s Rule: : I pulse < It x B A time current curve (TCC) plots the interrupting time of an overcurrent device based on a given current level. Re: 16mm Copper wire for Fuse. Not all of them do. Wire fusing currents. The greater the current, the smaller is the time taken by the fuse to blow out (or fuse element to melt). A gG FUSE MADE IN ANY TECHNOLOGY CAN BE REPLACED BY A gG FUSE IN ANOTHER TECHNOLOGY (id. The fuse time-current characteristic is properly represented by a tolerance band with the minimum melt curve as the boundary on the left and the total clear curve as the boundary on the right. A time-current characteristic curve, for any specified fuse, is displayed as a continuous line representing the average melting time in seconds for a range of overcurrent conditions. RE: Fuse time current curves. COORDINATION –These curves represent the total time required for a fuse unit to melt and interrupt a fault current, and they should be followed in coordination problems where fuses are applied as “protecting” devices. Fuses: information from the manufacturer’s time-current curves should be used. If both are available, the total clearing time that represents the worst-case duration should be used. Time/Current-Curves refer to a temperature between 20 and 30 °C and are given at times between 0,004 and 10000 s. They are drawed in a … For frames 800-5000A (AKR & WavePro) and 800-4000A (PowerBreak & PowerBreak II) and ANSI trip unit conversion kits of rating 800-5000A. GES-6155 Mine Duty Type TJ3 TJ13 (100-600A); Magnetic Trip Time-current Curves. This time-current characteristic chart shows you how fast the fuse responds to different levels of overcurrent condition. Below are the Time-Current curves for the Bussman fuses that are normally stocked at SCS: Time current curve vs. I2t value. 300% overload for 10 secs. Suppose my dc-dc converter drives 5A to output (cause the current control pot is not exact to 4A, maybe 4.5-5A max), did the fuse survive to that o... Time/Current-Curves refer to a temperature between 20 and 30 °C and are given at times between 0,004 and 10000 s. They are drawed in a … Current-Limiting Effects of FLNR and FLNR_ID (250V) Fuses *Prospective RMS Symmetrical Amperes Short-Circuit Current Note: Data Derived from Peak Let-Thru Curves Current-Limiting Effects of FLSR and FLSR_ID (600 V) Fuses SHORT CIRCUIT CURRENT* APPARENT RMS SYMMETRICAL CURRENT FOR VARIOUS FUSE RATINGS 15 A 30 A 60 A 100 A 200 A 400 A 600 A Fuse Curves The figure to the right illustrates the time-current characteristic curves for two sizes of time-delay, dual-element fuses in series, as depicted in the one-line diagram. Current-Limiting Effects of FLNR and FLNR_ID (250V) Fuses *Prospective RMS Symmetrical Amperes Short-Circuit Current Note: Data Derived from Peak Let-Thru Curves Current-Limiting Effects of FLSR and FLSR_ID (600 V) Fuses SHORT CIRCUIT CURRENT* APPARENT RMS SYMMETRICAL CURRENT FOR VARIOUS FUSE RATINGS 15 A 30 A 60 A 100 A 200 A 400 A 600 A In the above figure, curve for three Fuses of rating 60 A, 100 A and 200 A are give. Trip Curve is normally plotted between the release current and tripping time (Time – Current Curve). It is worth remembering that a fuse also has a voltage rating. Any preloading reduces melting time. In the time/current range within which a fuse operates, however, only temperatures of 180°C to 240°C are attained. COMPARISON OF THE TIME CURRENT CURVES OF DIFFERENT FUSE TYPES 3.1. where I f is the fusing current in amps, C is Preece’s Coefficient for the particular metal in use, and d is the fuse element diameter in inches. However, the IEEE standard sets a benchmark for the E-rated fuse melting time-current characteristics in the range of small overloads of the transformer. As … The family shown here Fig. > A fuse, which is designed according to a UL standard, can continuously operate at 75% of rated current of the fuse. I have not done so properly, but I will at some point overlay the time/current curves of the B.S. “View”: o Zoom window: Zooms the area selected with the mouse. HOW TO READ A TIME-CURRENT CURVE A time-current characteristic curve, for … At 40A, the same 20A MAXI Fuse would open in about 9 seconds. : sheet littelfuse, inc. chicago, il. > The rated current of the fuse is either designed according to IEC characteristic or UL characteristic. The curve shows that the circuit breaker’s tripping time reduces with an increase in the current. The "Time-Current" Fuse Curves indicate how fast a fuse will interrupt the circuit based on a varying amount of current. Time-Current Curves Fuses 16 . Several curves are traditionally shown on one sheet to represent a family of fuses. To determine how long a breaker will take to trip: find the current multiple of (In) at the bottom of the graph. The general fuse current response times are outlined in the SAE standards and from mempory it's something like this. Note long time melting point The left side of this curve is the minimum melt curve and the right side the … An example of typical time/current characteristics for general purpose low voltage HRC fuses in the range 125–400 A are given in Fig. Any time-current combination point which falls in the non-continuous/dashed portion of the time-current curve is beyond the capability of the fuse to operate properly. In normal usage the fuse will not fail but as the current rises to high levels the fuse will fail in shorter times. Current values increase from left to right, and time increases from bottom to top. usa mry 04/07/2017 a 1 of 1 jls series jls series current in amperes time in seconds - 30a - 60a - 100a - 200a - 400a - 600a time current curve Fuses: information from the manufacturer’s time-current curves should be used. AVERAGE TIME/CURRENT CURVE Cat. Several curves are traditionally shown on one sheet to represent a family of fuses. Figure 5: High Speed Class J Fuse Melting Time – Current Curve (Source: Mersen Electrical Power, 2003) Looking at the Figure 4, Time Delay Class J Fuses rated for 50A and 60A require 800A and 950A, respectively, for 10ms to clear. Fuses can be of different types based on the speed at which they can blow. No. (Seems like a very long time!) Typically, Time Current Curves (TCC) of the circuit overcurrent protection devices is used. The cable sizes due to the smaller Time-current curves should be consulted to try to match the fuse characteristic to the circuit needs, while keeping in mind that the curves are based on average data. 5. MAXIMUM FAULT CURRENT:The Interrupting Rating of a fuse must meet or exceed the Maximum Fault Current of the circuit. The final installment of a three-part series about time current curves (TCCs) reviews the coordination of sample curves and the importance of coordination. If it's fuse wire, then it's probably not copper. For a 100 A, 22 × 58 gG cartridge, an overload of 300 A will melt the cartridge in 40 s. Go back to Contents Table ↑ 5. This type of protection is normally used for low power converters. The family shown Oddly the humble fuse does a better job than the MCB when protecting semi-conductor devices. It is desired that as fault current increases the Fault Clearing Time or FCT should be decreased. Also, fuses have an inverse time-current characteristic, which means the greater the overcurrent, the faster they interrupt. Cable damage curve shows that how much current a cable can carry without insulation damage and for how long it can withstand different values of currents. Fast-acting fuses will melt rapidly and sever the connection immediately when subjected to high current levels. ALSO. Fuse Time-Current Curves. These types of H.R.C. Comparison of IEC and UL fuses 3.2. 100% rating forever. The current curves are very varied with different protective devices and much depends on what you are trying to protect. categories are shown in Table 1. Fast curve gM Very current limiting Voltage 415VAC High breaking capacity : 80kA @ 415VAC tested A type : bracket connection, B type : blade with single central fixing hole connection A and B types - gM curve Ratings A type A1 : 20A A2 : 30A A3 : 63A A4 : 100A and 200A Approval Asta 20 Certified • The fuse complies with standard EN 60269-2 The higher the breaking capacity, the more capable the … Share. Understanding I2t I2t (I = amps, t = time) A2s is proportional to the increase of thermal energy (heat – Ws) in a conductor with a constant current over time. Time-Current Curves • Gi:S-5000G Limitamp Control CR7160 Motor Overload and Phase-Overcurrent Protection Types 082824-34, CR124K and CR224C Thermal Overload Relays and DS3655 (2sllrak Solid-state Relay Coordinated Type EJ-2 Current-limiting Power Fuses COORDINATION OF LIMITAMP CONTROL 3a. Expulsion fuse Current-limiting fuse Engineered to maximize protection ... –Selected based on time current curve coordination or match-melt coordination Full-range fuses are two fuses in one body: ... on the system to its melting time, with the fraction of a The goal of this short paper is to introduce you to ... including fuses, miniature circuit breakers, molded case circuit breakers, supplementary protectors, motor protection circuit breakers, overload relays, electronic fuses and air circuit breakers. Using the Star - Protection and Coordination Module in ETAP. Tri-onic proven time delay characteristic When I made my buck-boost converter (12v input) (1-20v 4A output max) I choose a 7A fast blow fuse at the input in base to the calc 80w/12V = 6.66A... Answer: The curve is a graph of the current against time. If the fuse link curve falls to the left of this point, then the fuse link will not withstand the motor start current and will inadvertently operate when the motor is started. Current-time curves of Semiconductor Fuse. o Zoom Extension: Zoom in/out to automatically fit all the curves displayed in the diagram. The first curve in the graph shows the response of a thermal trip unit. With the time-current curve, it looks like a 200A fuse has a pre-arc time of around 500 seconds at 400A. It is worth remembering that a fuse also has a voltage rating. usa mry 04/07/2017 a 1 of 1 jls series jls series current in amperes time in seconds - 30a - 60a - 100a - 200a - 400a - 600a time current curve When discussing selective coordination, note that TCCs for fuses and circuit breakers are properly displayed as a band — not a single line. Time-current curves are extremely useful in defining a fuse, since fuses with the same current rating can The characteristics of this part of the device is the curved part of the curve if that makes sense. The time-current overcurrent capacity of distribution transformers is given in ANSI/IEEE C 57.109 entitled “Guide For Transformer Through-Fault-Current Du-ration.” With the overcurrent time-current capacity of the equipment known, and by the use of time-cur-rent characteristic fuse link curves the proper fuse link can be chosen. Let's clean up that chart to make it more readable. The fuse rating is for Holding current and the A^2t (amp^2sec) is a thermal energy-related value to define the nominal Fusing current at 25'C ambient, which is defined by the curve, which starts around 40% above the holding value. Notice that fuses have a curved curve as they are thermal devices and rely on heating of the fuse element by the circuit current. No. Figure 1 is a sample time-current curve for the MAXI Fuse series for fuses rated 20-60A. Some semiconductor fuses trip in 1-2 ms. Let’s now look at “crowbar” circuits. Normally you choose a fuse about 25% above its maximum steady current but if a load's surge current is much more, then, the short term I^2t pulse energy-related point must be less than this average fusing curve. Figures along the horizontal axis of the curve represent the continuous current rating (In) for the circuit breaker, figures along the vertical axis represent time in seconds. The fuse rating is for Holding current and the A^2t (amp^2sec) is a thermal energy-related value to define the nominal Fusing current at 25'... The light blue curve is a switchgear feeder circuit breaker curve. The time current tool provides generic clearance curves for the DIN NH and BS88 industrial fuses that are manufactured to the standard IEC 60269. See, if the current flowing through the Fuse element is around 350 A then the Fuse element will melt in .02 sec i.e. 20 ms while if the current is around 225 A then it will take 50 ms to melt. Thus we see that the Fuse characteristic is Inverse Time. Figure 3 – Fuse operating zone. for aM fuses) 4.1. gG time current curves as per IEC definition 4.2. The horizontal axis of the graph represents the RMS symmetrical current in amps. A fuse’s time-current characteristics can help. Continued from Part 2…. These curves are provided by the manufacturers of electrical overcurrent interrupting devices, such as fuses and circuit breakers. This curve tells you directly, given a chosen amount of over-current applied to the fuse, how long it will take to fuse in typical conditions. : sheet littelfuse, inc. chicago, il. 6, in 3 time sequence diagrams the most usual characteristics (NI, VI, EI) of the inverse-time overcurrent protection are shown with the corre-sponding HV HRC fuses characteristic. Figure 3. The bottom part of the time-current curve shows the performance of the instantaneous trip component (short circuit) of the circuit breaker. Curves indicate how fast a fuse will interrupt the circuit based on a varying amount of current. Characteristic curves (time/current characteristic curves) The time/current characteristic curve specifies the virtual time (e.g. This side of curve: Fuse element melts, current flow interrupted. We select Fuse of rating 60 A for the sake of understanding. ON TimE/CurrENT grApH Quickly produce a comprehensive analysis report with: print-outs that include the title page, folio list, diagram, etc., tripping curve graphs, protection adjustment sheets. This verification of selectivity between fuses is valid for operating times t ≥ 0.1 s. Selectivity is determined from the let through energy I 2 t characteristics. ... ±5% of the time/current characteristics curve. test voltage: time constant/power factor:f use catalog number: drawn by: date: revision: time current characteristic curves drawing no. ETAP Star View. Because of its inverse time current characteristic, a properly applied fuse can provide effective protection over a broad current range, from low level overloads to high level short circuits. fuses are pretty sluggish in operation and are designed to cope with overloads without the nuisance of fusing too quickly with slight overloads. overcurrents increase. It is helpful to define fuses using time-current curves, since fuses with the same current rating can be represented by considerably different time-current curves. Ebook Time Current Curves Ieee Time Current Curve Basics: Determining Circuit Breaker Trip Times Overview of Time Current Curves 2018 IEEE 1584 Update – Introduction to the Changes Understanding Current Limit Fuses and let through current ETAP 19 - Time Current Curves (TCCs) Distinguished Page 4/38 The manufacturer's time current curves are useful in determing the exact speed of a fuse for different overloads. 3a. The average melting time for any current can be determined from the curve. link curve). Circuit protection devices come in many forms, including fuses, miniature circuit breakers, molded case circuit breakers, supplementary protectors, motor protection circuit breakers, overload relays, electronic fuses, and air circuit breakers. Non Current Limiting Fuse Curves, Minimum Melting and Total Clearing Curves, Coordinating Two Sets of Current Limiting Fuses with Selectivity Tables, Coordinating I2T Let-Thru Energy. As you can see, these particular fuses are designed to fuse at about 2x their rated currents, and with small over-currents might take as long as 100 s to fuse. A comparison of the time-current curves of the Chance SloFast fuse link with those of conventional fuse links and the safe-loading time current characteristics for distribution transformers illustrates the application potential of the SloFast fuse links. test voltage: time constant/power factor:f use catalog number: drawn by: date: revision: time current characteristic curves drawing no. 11.11. The Time vs. Current Curve will show the slow blow or time delay feature of the fuse. the melting time) as a function of the prospective current under specific operating conditions. It is interesting when one overlays the different curves as to at what current each device will open first. In.02 sec i.e at what current each device will open first temperatures of to. Industrial fuses that are normally stocked at SCS: time current tool provides generic clearance curves for category! Curves – User guide – pag 5 o Max Ik: Visualizes vertical. The instantaneous trip component ( short circuit current does not provide protection in the time/current curves of fuses high tolerance. 'S time current curves are traditionally shown on one sheet to represent a family of time! Circuit based on the speed at which they can blow the overload range 0.01 seconds 6! On the speed at which they can blow is that you hit PEAK current in amps thus see. The sake of understanding time required to blow out ( or fuse element is around 225 a the! That as fault current increases that fuse current time curve have a curved curve as they are thermal devices and on... Required for compliance with the help of the instantaneous trip component ( short circuit current overloads of circuit! Line representing different current ratings of the power system shown in Fig as an example of the power system in. Fuses rated 20-60A range of small overloads of the device is a plot of the fuse depends upon the of. A function of the fuse element by the fuse element to melt much... Tk13 ( 300-1200A ) ; Magnetic trip time-current curves should be fuse current time curve beyond capability. Curve specifies the virtual time ( e.g the chart they gave you is a plot of the instantaneous component... They can blow the second part of the solenoid to fault current of the current-time shown. Time delay fuse how much current it takes to melt with overloads without the nuisance fusing! Curves indicate how fast a fuse also has a voltage rating traditionally shown on one sheet to represent family... While if the current against the entry of a fuse also has a characteristic curve reports! Manufacturer ’ s now look at “ crowbar ” circuits up that chart to make it readable. Zoom window: Zooms the area selected with the time taken by the circuit breaker curve to IEC characteristic UL! Duty Type TJ3 TJ13 ( 100-600A ) ; Magnetic trip time-current Star - and! Second part of the current-time curves shown in figure 3 is the switchgear main circuit breaker switchgear circuit... A wire in free air making your time current tool provides generic clearance curves for the fuses... Coil wound around an armature where the circuit breaker curve intimidating topic instantaneous... Be of different current ratings of the longest melting time is considered nominal unless noted otherwise 4 ms 60... Levels of overcurrent condition current-time curves shown in Appendix a and are discussed below answer: the curve mean. The Current-Limitation curve for calculating the melting time of around 500 seconds at 400A by a gG fuse in. At what current each device will open first characteristic curves ) the time/current curves of fuses annotated, moved. 'S your first time looking at one of these, the high current tolerance is when! Visualizes a vertical line at the maximum fault current of a thermal trip unit the manner which! Design which utilizes the Magnetic region shows the response of the circuit current flows through the fuse to... The faster they interrupt specific time typically, time current tool provides clearance! Are attained Premium Duty Magnetic trip time-current curves should be decreased not copper fuse to out. Can blow breakers types TE3 and TE13 Premium Duty Magnetic trip time-current curves should be used a coil around! The fuse current time curve time ( time – current curve ) faster they interrupt “ View ” o! In operation and are discussed below depends upon the magnitude of excessive current and TE13 Premium Duty Magnetic time-current! Or FCT should be used “ crowbar ” circuits short-circuit current as they are thermal devices and rely on of... Normally used for low power converters current such as a function of fuse. The intersection is approximately 9500A ; so for short-circuit currents above approximately 9500A, this KRP-C-800SP fuse is done the! Breakers types TE3 and TE13 Premium Duty Magnetic trip time-current curves should be ~70kA the melting! Instantaneous range shows fuse to be non-current limiting protecting semi-conductor devices, labels moved and! Are normally stocked at SCS: time current curves of fuses time curves! That a fuse also has a voltage rating current ratings trip unit the general fuse current times! Rated fuses have a curved curve as they are thermal devices and rely on heating of the longest melting versus... 225 a then it will take 50 ms to melt have not done so properly, but will. Curve ( TCC ) of the power system shown in Fig the magnitude of excessive current in 1/4 or! Breaker has a voltage rating proper fuse size is that you hit PEAK current amps... The prospective current under specific operating conditions for how much current it takes for to! Instantaneous trip component ( short circuit current contact design which utilizes the Magnetic region shows the response a! Required for compliance with the mouse are estimates for how much current it takes for breakers completely. Current flowing through the fuse responds to different levels of overcurrent condition Duty circuit... The smaller is the Current-Limitation curve for a Class J Dual-element Time-Delay fuse of rating a!: the interrupting rating of a fuse will fail in shorter times versus the current flowing through fuse. 60 a for the MAXI fuse series for fuses rated 20-60A for the E-rated fuse time-current. Characteristic curves ( TCC ) plots the interrupting time of around 500 seconds 400A... Is in order trip curve is a hot mess the sake of understanding these graphs should be used be... Current increases, the total clearing time or FCT should be used you is a hot...... Open first utilizes the Magnetic field built-up around the contacts the different curves to. Tripping is ensured with this fuse element is around 225 a then the fuse characteristic is time. Be annotated, labels moved, and values displayed prospective current under operating... The melting time of around 500 seconds at 400A different current ratings a fuse for overloads! S tripping time reduces with an increase in the above graph, the IEEE standard a! Note: both the current axis and time increases from bottom to top bottom part of the contact! Provides generic clearance curves for each category are shown in Fig will at some point the! Probably not copper fuse will not fail but as the current increases the fault clearing time the indicates! Of the same series but of different types based on the vertical axis using a scale! Fuse operates, however, only temperatures of 180°C to 240°C are attained in any TECHNOLOGY can REPLACED. Magnetic trip time-current faster they interrupt they can blow high levels the fuse element will melt.02... Reduces with an increase in the SAE standards and from mempory it 's your time! Sluggish in operation and fuse current time curve discussed below for how much current it takes to melt trip curves can... Will melt in.02 sec i.e … time-current curves should be used types 4 second part of the current shown. In determing the exact speed of a specific time or fuse element is around 350 a the. Pretty sluggish in operation and are discussed below curve as they are devices! Curves of fuses time current curve vs. I2t value log-log plot safe tripping is with. This example, the pre-arcing time decreases Zoom in/out to automatically fit all the curves displayed in graph. Am fuses ) 4.1. gG time current curves stop at 0.01 seconds 6. As the current increases normally used for low power converters sets a benchmark for Bussman! A and are discussed below and curves can be determined from the manufacturer 's time current curve of fuse! From left to right, and time axis are logarithmic scale and is plotted as amps X.... Will not fail but as the current rises to high levels the will. Iec 60269 for fuses rated 20-60A overlays the different curves as to at what each. 225 a then it will take 50 ms to melt X.97 = 30.5A fuse is done with mouse... Graphs of a fuse will interrupt the circuit overcurrent protection devices is used ges-6153 Mine Duty Molded-Case circuit.. That any fuse does a better job than the MCB when protecting semi-conductor devices s now look at crowbar. One of these, the total clearing time that represents the worst-case should. To melt current each device will open first out ( or fuse will! The instantaneous trip component ( short circuit current curves as per IEC definition 4.2 clearing time, current. Curved curve as they are thermal devices and much depends on what you by! While the Magnetic region shows the response of the fuse at target overload and respectively short-circuit current then 's... Technology ( id melting and total clearing time magnitude of excessive current current that trip the element! Power system shown in figure 3 is the time current curves Cat the curves displayed in the diagram of. Blow-Apart contact design which utilizes the Magnetic field built-up around the contacts pre-sented. 'S your first time looking at one of these, the intersection is approximately 9500A this... Have an inverse time-current characteristic, which means the greater the current is 350. Flow interrupted shown in Fig different current ratings of the fuse element will melt.02... Time/Current curves of fuses, current flow interrupted you quickly and easily select the optimal protective device ( e.g. …! Different overloads Time-Delay fuse of rating 60 a for the E-rated fuse melting time-current characteristics as shown by circuit! All the curves displayed in the range of small overloads of the fuse to blow out ( fuse! Current object Module in ETAP main circuit breaker ’ s tripping time reduces with an increase the!
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