Semiconductor Fuse : Construction, HSN code, Working & Its Applications

A fuse is an electrical protection device used to protect the circuit from overload, overcurrent, etc. An electric fuse was invented by Thomas Alva Edison in 1890. These devices come in different sizes, however, they all are used for the same purpose. Fuses are classified into two types AC fuses and DC fuses. So this article discusses one of the types of DC fuse namely – a semiconductor fuse, working with applications.

What is Semiconductor Fuse?

A semiconductor fuse is a current protection device that is also known as a high-speed fuse or ultra-rapid fuse or rectifier fuse.  These are mainly designed to limit the high current and protect sensitive semiconductor components like thyristors, power supplies, SCRs, rectifiers, diodes, etc. These fuses are very fast-acting, and current-limiting devices that provide peak let-through currents & low melting integral values. Generally, these fuses range from 125 to 2,100 V and are accessible in a wide range of sizes and shapes.  The semiconductor fuse symbol is shown below.

Construction of Semiconductor Fuse

A semiconductor fuse construction is shown below which a fuse element has and it is surrounded by filler & enclosed by the fuse body. The fuse element within this fuse is made with oxidant-resistant fine silver. The silver material has a melting point of 960°C which can resist the maximum operating temperature of the limiter. The body of the fuse is made with thermally stable aluminum oxide ceramic.

The semiconductor fuse is also known as a high-breaking capacity or current-limiting fuse. Sometimes, these are called ultra-fast fuses or rectifiers. The time taken to melt the fuse element is called prearcing time.

Working of Semiconductor Fuse

The working of a semiconductor fuse is to allow the current flow supplied from the power source to the circuit to power the circuit properly. If a short circuit or overload occurs, then the current supply can crack the filament in the fuse & cut the power source connection throughout the circuit. So when the limit of predefined current is reached, the fuse will disconnect a circuit. These fuses will replace AC and DC fuses in many areas.  Any overload currents will cause a fuse to open the circuit & avoid circuit damage. These fuses are typically used to protect semiconductor components like transistors, integrated circuits, diodes, etc.

Semiconductor Fuse Vs HRC Fuse

The difference between a semiconductor fuse and an HRC fuse is discussed below.

Semiconductor Fuse Selection

The semiconductor fuse selection can be done based on the following requirements.

• In normal operating conditions, this fuse should carry the rated current of the device continuously.
• The I2t fuse value must be low as compared to the rated I2t of the device so that the fuse will blow before the device.
• The fuse must be capable of resisting the voltage that appears across it after the extinction of the arc.
• The voltage of the peak arc must be low as compared to the rating of the peak voltage of the device so that the device cannot damage.
• This fuse selection mainly depends on practical requirements like I²t Rating, voltage rating, braking capacity, size & rating of the fuse holder, Fuse Class gS & gR, aR & gPV, Physical limitations within the design or on-site, small current rating, available ratings range in every package type, etc.
• The semiconductor fuse selection for soft starters must be very careful to protect the thyristors used in every soft starter & the continuous current rating.

Semiconductor Fuse Characteristics

• The current-time semiconductor fuse characteristics are shown below. We know that a fast-acting fuse is utilized to defend semiconductor devices. When this fuse is connected to a semiconductor device in series & once the current increases its rated value then it will open.

• When this fuse is not used within the circuit, then the fault current increases up to point ‘B’. When the fuse current enhances, then temperature also enhances. Similarly, when the fuse is used within the circuit, the fault current enhances up to time t = tm. So, there is a spark across the fuse once it opens at t = tm time.
• The fault current enhances up to point A which is known as Peak through let current that is indicated with point C. At point C, when the arc resistance enhances the fault current reduces.
• At point D, the arc reduces & fault current turns zero at that time. The tc (fault clearing tim) is the addition of tm (melting time) & ta (arcing time) of the fuse like tc = tm + ta.
• The voltage across the fuse throughout arcing time is called an Arcing voltage or Recovery voltage. So, it must be noted that the fuse I^2t rating is always below the SCR I2t rating.

What is the HSN Code of Semiconductor Fuse?

Generally, Harmonized System of Nomenclature or HSN code was developed by the WCO (World Customs Organisation) which is used for classifying various goods. It is a 6-digit code, typically used for different goods. But, some countries utilize 8-digit codes for sub-classifying goods. So, the HSN code of the semiconductor fuse is 853610.

How to Check Semiconductor Fuse?

A semiconductor fuse can be checked through the apparatus by selecting a fuse, isolating the capacitor, forcing a voltage to the fuse & current demand measuring for the fuse. A first current level specifies an unbroken fuse whereas a second current level specifies a blown fuse.

Applications/Uses

The applications or uses of semiconductor fuses include the following.

• Semiconductor Fuses applications mainly include semiconductor devices protection in power rectifiers, AC & DC motor drives, converters, soft starters, photovoltaic inverters, solid state relays, welding inverters, etc.
• These fuses are broadly used in the power electronics applications such as Variable frequency drives, thyristor DC drives & Uninterrupted Power Supplies.
• This Fuse is used to protect the devices from large currents.
• These fuses are used in different applications like protection of short circuits, overvoltage, overcurrent, slew rate control, TSD (thermal shutdown) & RCB (reverse current blocking).
• This fuse is a very fast conventional fuse that protects a semiconductor device from damage.
• This fuse is normally used with larger semiconductor devices that are rated to switch 100A or above.

Thus, this is all about an overview of semiconductor fuse – working with applications. These protection devices help in protecting the semiconductor devices from short circuits. The semiconductor fuse has super fast acting characteristics particularly developed for semiconductor power devices protection. Here is a question for you, what is HRC fuse?