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1 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Training Agenda 1.Fuse Definition.

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Presentation on theme: "1 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Training Agenda 1.Fuse Definition."— Presentation transcript:

1 1 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Training Agenda 1.Fuse Definition and Telecom Circuit Protection Needs 2.WIA Fuse Characteristics and Device Physics 3.WIA Fuse Telecom Application Protection Examples 4.WIA Fuse Telecom Application Product Selection 5.Littelfuse WIA Fuse Product Road Map 6.Telecom WIA Fuse Technology Challenges

2 2 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Section 1 Section 1 Fuse Definition and Telecom Circuit Protection Needs Fuse Definition –A fuse is a calibrated, intentionally weak link in an electrical circuit that provides over-current protection. Circuit Protection Needs in the Telecom Segment –Lightning –ESD –Inductive –Short Circuit/Power-Cross Fuse Technology for Telecom Overcurrent Circuit Protection –Elimination of series line resistance enabling longer loop lengths –Precise longitudinal balance allowing better transmission quality Typical Telecom Test Standards –ITU K.20 K.21 –Bellcore GR-1089 –UL Typical Fuse Test Standards –IEC –UL 248 –MITI

3 3 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Fuse Definition and Telecom Circuit Protection Fuse Definition –A fuse is a calibrated, intentionally weak link in an electrical circuit. –Fuses function by reacting to the heat generated from excessive current flow. Once the fuses I 2 t rating is exceeded, the center conductor opens. –A fuse is used to prevent fires and overheating when something goes wrong with electrical equipment. This can be the result of an accident, such as unintentional contact between power and the telephone line, an improper connection/installation, poor maintenance work, or a vandalism. –A fuse is intended to operate before a catastrophic event occurs and can create a safety hazard. Electrical components such as capacitors, transformers, resistors, etc., can fail due to a manufacturing defect or old age, and could draw an excessive amount of current and catch fire. –A fuse does not prevent a fault from occurring, but will operate quickly to prevent further damage occurring or the equipment becoming a safety hazard. The fuse can also limit the extent of the damage to a small portion of the equipment making repairs less costly –IEC, UL, MITI, and CCC standards all provide definitions and requirements for fuses. For example, IEC-127 gives specific dimensional requirements and also specifying a series of fuse tests.

4 4 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Fuse Definition and Telecom Circuit Protection Circuit Protection Needs in Telecom Systems –Thunderstorms around the world deliver 8 million lightning flashes every day. Peak current in lightning discharges range from a few KA to many hundreds of KA. Induced currents from indirect strikes range from 10A to 20KA. –ESD results from the build up of electrical charge, when two non-conductive materials are brought together then separated. The potential between a human body & an object can exceed 35,000 volts. An ESD event can occur to the telecom system or portable devices through human contact and usage of the telecom devices. –Inductive Load Switching is caused when an inductive load is interrupted. It occurs in factory/industrial environments where motors and relays (inductive loads) are turned on and off. –Short Circuit or Power Cross events can occur due to human error (such cutting a phone and power line simultaneously during construction) or natural disaster such as hurricane, thunderstorm. –One or a combination of the above threats can have obvious adverse effects on semiconductor/IC devices, electro-mechanical contacts, wiring insulation, etc., to cause interruption of telecom equipment operation, telephone service, and even fire.

5 5 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Fuse Definition and Telecom Circuit Protection Fuse Technology for Telecom Overcurrent Circuit Protection Telecom equipment should be protected from overcurrnent conditions using either PTCs, fuses, power/line feed resistors, or flameproof resistors. –A Fuse is a series element placed in front of the overvoltage protector on either Tip or Ring for metallic applications and on both Tip and Ring for longitudinal applications. Due to their stability, fuses are one of the most popular solutions for meeting AC power cross requirements for telecommunications equipment. –Littelfuse Telecom WIA Fuses are designed to only interrupt a circuit when extreme fault conditions exist and, when coordinated properly with an overvoltage protector, offer a very competitive and effective solution for transient immunity needs. Advantages include: Elimination of series line resistance enabling longer loop lengths Precise longitudinal balance allowing better transmission quality Robust surge performance which eliminates costly down time due to nuisance blows Greater surge ratings than resettable devices, ensuring regulatory compliance Non-degenerative performance –Telecommunication equipment best suited for a fuse is equipment that requires surface mount technology (and is thus sensitive to transients), accurate longitudinal balance, and regulatory compliance without the use of additional series line impedance.

6 6 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Fuse Definition and Telecom Circuit Protection Telecom System Test Standards SwitchSLICMDF Underground Cable Overhead Cable Street Cabinet & SLIC (if on DLC system) Network Interface Device (NID) Customer Premise Equipment (CPE) Central Office Subscriber Premises DDF Outside Plant YD/T993 ITU-T K.21 FCC P 68 UL YD/T993 ITU-T K.21 FCC P 68 UL UL 497 YD/T1082 ITU-T K.45 GR 1089 UL UL 497 YD/T 694 or YD/T 940 ITU-T K.28 GR 1089 UL UL 497 YD/T950 ITU-T K.20 GR 1089 UL To PSTN Trunk Line (T1, T3, HDSL, etc.)

7 7 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Fuse Definition and Telecom Circuit Protection WIA Fuse Standards –IEC 127 Specification 5 BASIC GATES –HOLD 1.5In 60 MINUTES –OPEN 2.1In 30 MINUTES (2MINS T ) –OPEN 2.75In VARIES T/F HBC/LBC –OPEN 4.0In VARIES T/F HBC/LBC –OPEN 10In F 20mS BREAKING CAPACITY 250V ac –HBC HIGH BREAKING CAPACITY 1500A –LBC LOW BREAKING CAPACITY 35A or 10In –EBC ENHANCED BREAKING CAPACITY 150A FUSING FACTORS –1.7 OF FUSE RATING –UL 248 Specification 3 BASIC GATES –HOLD 110% 4 HOURS * (UL198G) –OPEN 135% 1 HOUR –OPEN 200% 2 MINUTES INTERRUPTING RATING –125V 10kA –250V 35A to 1500A FUSING FACTORS –1.2/1.3 OF FUSE RATING –MITI Specification 3 BASIC GATES –HOLD 130%60 MINUTES –OPEN 160%60 MINUTES –OPEN 200% 2 MINUTES INTERRUPTING RATING –125V 500A –250V 100A FUSING FACTORS –1.5 OF FUSE RATING

8 8 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Section 2 Section 2 WIA Fuse Characteristics and Device Physics –Basic Fuse Characteristics Electrical Characteristics –TC Curve –I 2 t –Fast Acting and Slo Blo Fuses Maximum Ratings (Breaking Capacity) –Fuse Voltage Rating –Pulse Withstanding Curve Thermal Characteristics –De-rating –Fuse Construction and How it Affects Fuse Characteristics Fuse Construction Fuse Physics and Equations Fuse I 2 t and Arcing Fuse Element: Slow-blow vs. Fast Acting Fuse Body Strength and Breaking Capacity

9 9 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics Basic Fuse Electrical Characteristics –TC Curve Defines the fuse opening time Illustrates phase change of the fuse element state Directly denotes the fuse rating Difference in Slow Blow vs. Fast Acting Typical overload 200% to 800% for electronics fuse Above 1000% considered to be short circuit –I 2 t 1. Adiabatic Process: No heat transfer to surrounding. All energy concentrated in a specific area for a split second. 2. Measure of the energy required to open a fuse when subjected to an adiabatic current pulse. 3. Due to adiabatic current pulses, the fusing element is stressed both thermally and mechanically. Depending on the energy and number of pulses it could weaken due to aging: - Fatigue - Pre-diffusion - Oxidation

10 10 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics –Fast Acting vs. Slo Blo Fuse Slo Blo: Fast Acting: t =2 Separation t =4 Plasma expands, Burn Back continues t =3 Arcing Starts and Burn Back of Element Arc Extinguished Fuse Operated t = 0 solidt =1 liquid solid & liquid base=solid, pellet=liquid, mix=solid & liquid diffusion process on going t = 0 base=solid, pellet=solid t = 1 base=solid, pellet=liquid diffusion process starting t =2 liquid alloy (base+pellet) t =3 Separation t =5 Plasma expands, Burn Back continues Arc Extinguished Fuse Operated t =4 Arcing Starts and Burn Back of Element

11 11 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics Maximum Ratings (Breaking Capacity) –Fuse Voltage Rating The maximum system voltage for which the fuse can be used without affecting the breaking capacity. When Fuse is subjected to high voltages (>rated voltage) and high currents (> rated breaking capacity), the fuse may explode. Interrupt Rating = Breaking Capacity = Prospective current a fuse can interrupt safely at rated its voltage: - No damage to environment - Fuse remains intact - Insulation resistance maintained –Pulse Withstanding Capabilities Ability of fuses to sustain a number of adiabatic current pulses containing a specified amount of energy with sufficient cooling in between. - Pulse in % of I²t value - Fuse remains intact with a minimum aging

12 12 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics Thermal Characteristics –De-rating Curve and Fuse Re-rating Temp. of Fusing Element = Ambient Temp. (T A ) + Temp. Increase caused by Current Flow (dT) °C Fast Acting fuse Slo-Blo fuse ( 232°C) Ta dT temperature (°C) The influence of ambient temperature is for Slo Blo fuses much larger then for Fact Acting fuses. +

13 13 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics –Fuse Elements normally consist of a conducting metallic strip or filament of varying geometries and materials depending upon the ampere rating and application –Connective Material typically solder or conductive epoxy –Body material selected to survive Breaking Capacity/Pulse Withstand ratings safely –Filler can aid in achieving specific ratings while maintaining safe operation –Specific Fast or Medium Acting fuse element designs –Specific Slo-Blo or Time delay fuse element designs Fuse Construction Filler Terminations (End Cap) Connective Material Element/Filament Body Connective Material Terminations

14 14 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics Fuse Physics Equation TC Curve Equation Defined as the difference between the heat generated and the heat lost to the surroundings by the fuse element is the remaining heat energy required to raise the temperature of the fuse element to its melting point. Written as: Q I – Q L = mC P ( (T E -T S )/Δt) ) = ρA X LC P ( (T E -T S )/Δt) ) where: Q I = Heat Generated by Current = I²RC P = Specific Heat of conductor Q L = Heat Lost to SurroundingsΔt = Temperature change of conductor m = Mass of conductorL = Length of conductor I 2 T Equation Joules Law can be written as: Power (P) = I²R = mC P ΔT / Δt where: m = Mass of conductor C P = Specific Heat of conductor ΔT / Δt = Rate of Temperature change of conductor Slo-Blo vs. Fast Acting Equation Resistance is expressed as R = pL / A where: p = Resistivity of material (ohm-length) L = Length of material A = Cross Sectional Area of material

15 15 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics Fuse I 2 t and Arcing

16 16 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics Fuse Elements: Slow-blow vs. Fast Acting Non Diffusion (Fast Acting) Diffusion (Slo-Blo) Non Diffusion (Fast Acting)Diffusion (Slo-Blo) At high overloads a Slo-Blo in principle acts like a Fast Acting fuse because no time is available to start the diffusion process. - High overloads: about 4In (4x current rating) and higher. Diffusion starts at °C. Slo-Blo fuse elements should not be operated continuously above 150°C to prevent aging. Although no Sn pellet / plating is present it is not recommended to load Fast acting fuses continuously above °C due to: - Oxidation of the fusing-element material - Change of material properties

17 17 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Characteristics and Device Physics Fuse Body Strength and Breaking Capacity Interrupt Rating = Breaking capacity Prospective current a fuse can interrupt safely at its rated voltage. - No damage to its environment - Fuse body remains intact - Insulation resistance maintained (> 0.5MOhm) Rated Voltage / Voltage Rating: - The maximum system voltage for which the fuse can be used without affecting the breaking capacity - Typically 32, 63, 125, 250, 600V - The rated voltage is marked on the fuse body or terminations (end caps) Breaking Capacity Factors 1. Air Pressure from out-gas (due to fuse opening) cannot be larger than fuse body can withstand 2. Temperature of fuse body due to fuse element melting and arcing must not be higher than the ignition temperature of the fuse body 3. Fuse arcing time (time to extinguish) must not be longer than fuse body can withstand (could cause ignition or even vaporize fuse body) "Equivalent Fuse Body I 2 t" as Breaking Capacity.

18 18 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Section 3 Section 3 WIA Fuse Telecom Applications Protection Examples –Basic OV - OC Connection Topology OV-OC Unit for Telecom Circuit Protection –Circuit Protection Based on Telecom Applications Requirements Customer Premises Equipment –Transformer-Coupled Tip and Ring Circuits High Speed Transmission Equipment & Interfaces –ADSL –T1/E1 Protection –IDSN Analog Line Cards –SLIC Protection Data Line Protection –LAN/WAN Protectors –Littelfuse Global Lab Capabilities Qualification of Products UL-Approved Customer Testing Verification of Standards Customer Application Testing

19 19 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Protection Examples Basic OV - OC Connection Topology OC device (Fuse Open, PTC Trip) OV device to suppress transient OC device placed in front of OV devices (to help if OV device fails short) Example: Basic OV – OC Protection

20 20 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Protection Examples Customer Premises Equipment (CPE) CPE is defined as any telephone terminal or network equipment which resides at the customer's site and is connected to the Public Switched Telephone Network (PSTN) Protection Requirements: CPE should be protected against overvoltages that can exceed 800V and against surge currents up to 100A. It should meet regulatory standards such as TIA -IS-968 and UL Example: Basic CPE (Phone, Modem) Protection Application

21 21 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Protection Examples High Speed Transmission Equipment & Interfaces High speed transmission equipment encompasses a broad range of transmission protocols such as T1/E1, xDSL, and ISDN. Transmission equipment is located at the central office, customer premises, or remote locations. Protection Requirements: High speed transmission equipment should be protected against overvoltages that can exceed 2500V and against surge currents up to 500A. It should meet regulatory standards such as TIA -IS-968, GR 1089-CORE, ITU K.20/K.21, and UL Example: T1/E1 Protection Application

22 22 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Protection Examples Analog Line Cards Analogy Line cards are highly susceptible to transient voltages that are deployed at the central office and in remote switching locations. Protection Requirements: It is often necessary to protect Analogy line cards by on-hook (relay) and off-hook (SLIC) protection. It should meet regulatory standards such as TIA -IS-968, GR 1089-CORE, ITU K.20/K.21, and UL Example: SLIC Protection Application

23 23 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Protection Examples Data Line Protection In many office and industrial locations, data lines such as RS-232, Ethernet, and AC power lines run in close proximity to each other, which often results in voltage spikes being induced onto data lines, possibly causing damage to sensitive equipment. Protection Requirements Data lines should be protected against overvoltages that can exceed 1500V and surge currents up to 50A. Example: 10 Base-T Longitudinal Protection Application

24 24 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Protection Examples Global Lab Capabilities Qualification of all LF products UL-Approved Customer Testing in ISO Lab (Des Plaines) –High power (AC/DC up to 1KV/50KA) UL approvals available in DP –Telcordia approvals in DP planned (2008) Verification of Telcordia, ITU, IEC, FCC, and other industry, regulatory, and safety standards –Verification to various OC and OV standards Insure application meets standards before submitting for approval Customer Application testing –Assistance with design-in and performance verification Help with selection of appropriate technology and rating –Application troubleshooting Assistance insuring proper OV/OC and primary/secondary protection coordination –Competitive evaluations Competitive or technology performance comparisons –Reliability & Tin Whisker data/testing

25 25 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Section 4 Section 4 WIA Fuse Telecom Application Product Selection –Typical WIA Fuse Types for Telecom and Related Design Features Typical Axial Type Fuse (TR-5, Pico, 5x20, etc.) Typical Surface Mount Type Fuse (Nano, Telecom Nano) –Fuse Type/Series selection Identify Fuse Dimensional Requirements Identify Fuse Breaking Capacity Requirement –Fuse rating selection Identify Fuse Opening Time Identify Fuse I 2 t Requirement Identify Fuse De-rating Requirement

26 26 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Product Selection ApplicationDesign Feature RequiredWIA fuse Network Modems Analog, xDSL, ISDN, T1 Must meet UL rd Edition/UL 1549 and FCC 46 Part 68 specifications Tele-Link (461 series) 2AG Slo-Blo Fuse (230 Series) Desktop/PC-Card Modems Must meet UL rd Edition and FCC 46 Part 68 specifications 2AG Slo-Blo Fuse (230 Series) NANO Slo-Blo Fuse (452 Series) Fax Machines/Business Machines Must meet UL rd Edition/UL 1549 and FCC 46 Part 68 specifications Tele-Link (461 series) 2AG Slo-Blo Fuse (230 Series) Desktop TelephonesMust meet UL rd Edition/UL 1549 and FCC 46 Part 68 specifications Tele-Link (461 series) 2AG Slo-Blo Fuse (230 Series) Answering MachinesMust meet UL rd Edition/UL 1549 and FCC 46 Part 68 specifications Tele-Link (461 series) 2AG Slo-Blo Fuse (230 Series) Line Cards and PBXsMust meet UL rd Edition/UL 1549 and FCC 46 Part 68 and Bellcore GR1089-Core specifications Tele-Link (461 series) 2AG Slo-Blo Fuse (230 Series) Telecom/Internet Gateways Must meet UL rd Edition/UL 1458 and Bellcore GR1089-Core specifications Tele-Link (461 series) 2AG Slo-Blo Fuse (230 Series) Typical WIA Fuse Types for Telecom Applications

27 27 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Product Selection Fuse Type/Series selection Fuse Voltage Rating -The applied voltage fuse opens safely at (arcing occurs when fuse element melts, the voltage rating is the ability to suppress internal arcing) -Covered by NEC (National Electric Code) and UL -Standard voltage ratings: 32V, 63V, 125V, 250V, and 600VAC Fuse Current Rating -Fuse is sensitive to changes in current -Fuse will melt after heated by over-current conditions -TC (Fuse melting time vs. current) curve Typical Power Cross Requirement for Fuse -Meet 250V voltage rating for power cross -Meet 600V 40A (UL 60950) -Meet 600V 60A (GR 1089) The TeleLink or 461 series -Rated at 250V -Meet 600V 40A or 600V 60A test

28 28 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. WIA Fuse Telecom Application Product Selection Surge Rating Correlation to Fuse Rating Fuse Peak Pulse Current (Ipp) –Ipp >= Ipk, Ipk=Vpk/Rtotal –Longitudinal surges: Rtotal = Rtip + Rsource, Rsource=Vpk/Ipk –Metallic surges: Rtotal = Rtip + Rring + Rsource, Rsource= Vpk/Ipk Fuse Rating Selection

29 29 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Telecom WIA Training Section 5 Section 5 Littelfuse WIA Product Road Map –Wickmann Brand Fuse TR/TE -5 Fuse Road Map –Littelfuse Brand Fuse Telecom Nano Fuse Road Map 5x20 Fuse Road Map 2AG, 3AG Fuse Road Map

30 30 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. PROJECT Products Released in 2006 Products Expected to be Released in 2007 Target Segment 350V Fast Acting Cartridge Series Ballasts, UPS 350V Slo Blo Cartridge Series Ballasts, UPS Time Delay Pico Series Consumer Electronics METI B 3AB Series White Goods - Japan Mkt Various custom products ALL 3.6x10mm Platform SMPS High Amp Nano - 20A - 30A Computer / Server Enhanced Telelink Nano Telecom Telecom Fuse Array Telecom 1206 Nano Consumer Electronics, SMPS TE-5 100A Break Capacity SMPS TR-5 150A Break Capacity SMPS High I2t / HBC 215XA SMPS 5x20mm SMD Industrial 500V 6x32mm Fuse UPS IEC Barrier Fuse Industrial IEC Pico Fuse Industrial DC Rated Cartridge Fuses UPS TR-5 with 125C Operating Temperature SMPS Telecom WIA Training

31 31 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Physical value-added services for better overall efficiency 1.The complete package – Cartridge fuse with fuse-clip 2.Cartridge fuse ( or Pigtail leaded too ) with Color coded / band 3.Leaded fuses with kinking / lead forming 4.Fuse ( Direct welded type ) with lead forming 5.Fuse with heat-shrink tube 6.Fuse pigtail leaded type with longer pigtail lead length (for instance 52mm) 7.Taped and reeled/ammo-packed Telecom WIA Training

32 32 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Electrical value added services for specific/customized electrical applications and specifications 1.Enhanced breaking capacity / Short-circuit testing at ; Higher voltages Higher currents VDC testing 2Higher i2t request 3Addition of or in accordance with PSE IEC/UL 4.Increased of rated voltage of fuse 32v-rated to 125v-rated or even 250v-rated 125v-rated to 250v-rated 250v-rated to 350v-rated or any rated voltage needed 5.Tighter tolerance of parameters Resistance, length, i2t, etc Telecom WIA Training

33 33 Confidential and Proprietary to Littelfuse, Inc. © 2005 Littelfuse, Inc. All rights reserved. Section 6 Section 6 Telecom WIA Fuse Technology Challenges –Fuse TC curve definition and tolerance control –Higher Breaking Capacity/smaller package –Multiple elements in one package –Indication for open fuse –Fuse reset feature –Fuse technology combined with other technologies in one package –Improved de-rating characteristics –Higher operating temperatures Telecom WIA Training


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