Introduction to Fuse Markets
A fuse is an electrical or electronic circuit protection device that protects a circuit against overcurrent, by “melting” or “fusing” open its conductive element when an excessive and or overload “short circuit” current flows through it. Some fuses are single use designs, others are reusable designs; and this is an important distinction in the market. The combined dollar value of all fuse products electrical and electronic will represent about $2 billion in global revenues for 2014. This is an important dollar value, because fuses can also be considered part of the rapidly expanding “sensors” market because they sense and react to excess current in the system and functions as a circuit protection device. Therefore a closer look at fuses at this time is opportune and poignant.
Fuses by Technology
In the field of electronic fuses, the configurations employed are typically miniature and micro fuses that contain cylindrical or square bodies with ferrule end caps, terminations or leads, that have a rating from several milliamperes to tens of amperes, with voltage ranges from a few volts to 600 volts Automotive fuses can be considered a subset of the electronic micro-fuse business segment based upon their operating parameters, but because of their unique configurations (i.e. blade design) and operating environments, we consider them as a separate market segment. Larger type industrial fuses that are designed to handle extremely high currents at high voltage are also available and also considered a separate market because of the associated channels and customer base, and represent a significant amount of revenue for fuse vendors worldwide who sell to the industrial power equipment manufacturers. Ultimately, there are two basic forms of fuse technology and these are the 1) single element fuse; and 2) the twisted pair element fuse.
Single Element and Twisted Pair Element Fuses
Single element fuses employ a metallic wire inside a suitable enclosure usually glass or ceramic. The metallic wire is considered the fuseable element, which responds to increased temperature; which in turn is the by-product of increased current in the circuit. The fuse element is attached to the connecting end-caps on the fuse assembly, which is placed inside mating connections within the circuit. Thus the fuse becomes part of the circuit and is subjected to the current flowing through the circuit. During normal operation the fuse passes the desirable amount of current through the circuit, however, during an overcurrent situation the fuse acts like a positive temperature coefficient (PTC) device, and reacts quickly to the rise in temperature. The metallic wire fuse element will eventually melt with the corresponding rise in temperature resulting in an open circuit. Thus the sensitive electronic features of the product being protected remain viable as the circuit is taken off line by the blown fuse. Single element fuses are the most common type of fuse employed.
Twisted pair element fuses on the other hand, are manufactured by using two metallic wires made up of different metallic elements of unlike materials that are twisted together so that they become a compound element. The two types of wires have different temperature coefficients and melting points. Twisted pair element fuses are used in medium time delay fuse designs because they respond more slowly to an overload event when compared to single element fuses.
Fuses by Configuration
SMD chip fuse designs represent a significant amount of revenue for fuse vendors in their molded chip, solid ceramic matrix and thin film surface mount designs. In solid matrix or “thick film” designs the fusible link is enclosed in a ceramic filler material, which is placed in the fuse package-which is completely closed to outside elements and soldered into the circuit requiring overcurrent sensing. Surface mount fuses represent one of the fastest growth portion of the subminiature fuse business, and are typically purchased in 63Vdc rated packages, but may go as high as 125Vdc. SMD fuses are now available in standard footprints from the ultra small 0402 to the very large 6125 footprints. Subminiature fuses are consumed in telecommunications applications, personal computers, household appliances, switchmode power supplies, input/output modules, video game consoles and medical electronics.
The following chart illustrates the different types of surface mount fuses, which include molded chip designs; thick film solid matrix and sputtered thin film designs.
Figure 1: Molded, Thick Film and Thin Film Chip Fuse Types and Variations: 2014
Source: Compiled by Paumanok from Company Websites
Miniature Glass Cartridge Fuses
These axial leaded fuses are typically sold in 5X20mm and 6.3X32mm footprints. They are popular because they can be easily replaced by the end-user when used in conjunction with standard, high temperature, shock resistant, thermosplastic fuseholders. The core of the fuse may be either glass or ceramic, with nickel-plated brass caps. The rated voltage varies, but generally falls into the 250Vdc range; but higher voltage products in the 350, 440 and 500Vdc range are also widely used. Typical rated current handling capacity of miniature cartridge fuses are in the 32mA to 16.00A range. Miniature cartridge fuses are generally used in switchmode and other power supplies; lighting ballasts, consumer audio and video imaging equipment; household appliances; medical electronics equipment; measuring instruments and industrial controls.
The following chart illustrates the various types of cartridge fuses on the market, which is determined by their case size; and their intended or suggested applications.
Figure 2: Glass and ceramic Cartridge Fuses by Type and Application: 2014
Source: Compiled by Paumanok from Company Websites
Automotive Blade Fuses
Fuses consumed in automotive electronic subassemblies are either blade fuse or strip fuse types and are required to operate in low voltage and high current applications. Automotive electronic subassembly manufacturers have standardized these fuses into small, medium and large size categories. These devices are generally sold in 32Vdc, 80Vdc and 125Vdc ratings. The current handling capability of these fuses are typically in the 500mA to 50A ratings for blade fuses; 40A to 300A for strip fuses. In a standard car, the number of blade fuses will average 35 pieces and the number of strip fuses will average 15. This means there are 50 fuses per vehicle on average in the year 2000 and that this fuse content is doubling about every ten years. Automotive fuses are used in automotive electronic subassemblies such as ABS cards, engine control units, audio systems, navigation systems, security systems and other related automotive electronic subassemblies; however, due to the low voltage, high current aspects of these devices they are also used in telecommunications equipment, cable television, computers, household appliances and standby power supplies.
The following chart illustrates the various types of automotive fuses. Auto fuses will vary based on type, configuration, voltage, amps and performance characteristics as shown and discussed below.
Automotive grade fuses are required for the protection of
- Individual Automotive Accessories (Through the fuse box)
Figure 3: Automotive Fuse Variations by Type: 2014
Source: Compiled by Paumanok from Company Websites
Axial and Radial Leaded Micro-Fuses
Axial and radial leaded micro-fuses contain fuse elements molded into thermoplastic resin or aluminum housing. These designs are typically used in harsh environments and are tested to Mil-Spec standards for shock, vibration, moisture and corrosion resistance. Axial and Radial leaded fuses can be considered legacy and/or custom in the wake of the solid matrix fuse. These axial and radial leaded fuses usually find their applications in custom markets for defense, instrumentation, power, HVAC and specialty laboratory instruments.
Industrial Grade Power Fuses
Power Fuses are used in high amperage and high voltage applications, typically from 400Vdc to 1,000Vdc in load-centers, panel-boards, switchboards, bus ducts, feeder circuits, non-inductive loads, and HID lighting circuits. Smaller physical variations are also used in industrial motors and motor controllers (a large market). These are one-time use fuses that are fast acting and constructed to handle serious overcurrents to protect sensitive power related equipment.
The following chart illustrates the various types of industrial fuses. This is a significant market segment and the fuse variations largely are based on increasing levels of amperage and more demanding end-product applications in the power transmission and distribution infrastructure.
The reader can ascertain from the chart below, the various end-product applications that require industrial fuses. For example, we note that fuses are required throughout the power supply chain.
Especially for protection of
- circuit breakers
- speed drives
- lighting ballasts
Figure 4: Industrial Fuse Configurations and Sample Applications: 2014
Source: Paumanok Publications, Inc.- Please note that even though the UL lists fourteen variations of industrial fuses; most manufacturers supply six variations, including class L, class RK1 and RK5, Class J, Class CC, Class T and then the supplemental fuses.
Polymer PTC Resettable Fuses
Polymer PTC resettable fuses are made of conductive particles, such as carbon, scattered in a polymer matrix. Under normal operating conditions, little I2R heat is generated, and the conductive particles remain in close contact. When overcurrent occurs, the polymer heats above its transition temperature. The polymer matrix expands, causing the conductive particles to lose contact, which sharply increases device resistance. PPTC thermistors are the fastest growth portion of the business to 2019.
The following table illustrates specific applications for PPTC resettable fuses by end-use market segment and specific product applications within each segment. PPTC targets specific markets that have been dominated by one-time fuses for many years.
Figure 5: Telecom, Computer, Industrial, Appliance, Automotive, Consumer and Specialty Applications for Polymer PTC Resettable Fuses: 2014
Source: Paumanok Publications, Inc. Derives from Company Literature
Current Market Environment and Outlook
Global markets for automotive related fuses continues to outperform in FY 2015 (Year ending March 2015) and is having a positive impact on traditional blade fuses and cartridge fuses consumed in the automobile. There is also a supplemental increase in automotive sales of polymer PTC thermistors to protect DC motor assemblies. Additional polymer PTC markets are growing in tablet computers, but only for limited port protection, and the stagnation in the multi-port notebook and declining desktop markets has slowed over end-market growth in computers. Large home appliances and new television set designs are also positively impacting the fuse market as has renewed residential building activity which enhances demand for cartridge fuses and industrial fuses consumed in HVAC systems and gas packs. In defense there has been a slowdown in certain platforms, while aerospace platforms continue to outperform. The medical device markets, while small, continue to demand high margin premium components.
The outlook is more of the same for FY 2016; with growth continuing in the automotive sector, and an expected revival in demand for electronics consumed in photovoltaics and for wind energy electronics. The weakness in the yen continues to be alarming to the global market as pricing and quality are having an impact on global supply and demand as more OEM and EMS customers look to buy components in Japan to take advantage of the weakening yen.