Fuse

A: Fuses are rated by current, voltage, breaking capacity (interrupt capability) and whether they are designed to operate on AC or DC circuits. The current rating of a fuse is the current that it can carry for indefinite time periods without opening. The voltage rating relates to the ability of the fuse to function and extinguish internal arcs when it opens. The breaking capacity is how large a short-circuit or fault current the fuse can interrupt or stop safely without allowing a continuing arc and without damaging the fuse body or fuse holder.

A: Choosing the right fuse for your application is vital. A fuse is a protective device so if it’s not selected with care, the level of protection that your circuit will experience may be compromised. When your machine/circuit was designed, the designer carefully considered the level of protection that was required, so getting it wrong may have serious consequences. Also, please refer to ‘What is an Utilisation Category?’ in this section.

A: For all orders over $100 (excl. GST & freight), freight is FIS (Free into Store).
For all orders under $100 (excl. GST & freight), a freight charge of $25 + GST is applicable.
Additional fees may apply for deliveries to the Northern Territory and remote areas.

A: Fuses serve two main purposes:
To protect components and equipment from costly damage caused by over-currents.
To isolate sub-systems from the main system once a fault has occurred.

A: Fuses shall be selected according to the following criteria.
Maximum operational voltage – Shall be equal or greater than the system operating voltage.
Rated breaking capacity – Shall be equal to or greater than the maximum fault current expected in the circuit downstream the fuse.
Rated current – Shall be equal to or greater than the continuous operating current of the circuit protected by the fuse.
Breaking range – Partial range or full range breaking capacity according to the type of protection required.
Utilisation category – Select according to the nature of equipment to be protected.

A: Every fuse link has a specific ampere rating. In selecting the ampere rating of a fuse, consideration must be given to the type of load, circuit requirements and the intended protection performance. Naturally, the fuse current rating needs to be higher than the circuit normal operating current. As to the question of how much higher, there are a lot of factors that need to be considered before selection. For further advice on this topic, please contact Fuseco.

A: Fuse links are voltage sensitive devices and it is important to note that the satisfactory operation of a fuse link under fault conditions is dependent on the system voltage. Therefore they must not be installed in circuits with a voltage above their voltage rating. They can however be used satisfactorily in circuits at lower voltage levels. For example, you can use a 500V rated fuse in any circuit that has up to 500V.

A: Most LV fuse elements are made of copper (Cu). Fuse elements of fast acting fuses and HV fuses are primarily made of silver (Ag). Silver plated copper is also commonly used. As a rule, fuse elements of time delay fuses contain low melting point materials, e.g. tin (Sn) or zinc (Zn) and alloys thereof. Formerly used alloys containing lead (Pb) and cadmium (Cd) have widely been eliminated.

A: A fuse link is a thermal device and as such may require some de-rating when used at elevated ambient temperatures. Fuse links can carry rated current up to an ambient of 40°C. When the ambient temperature is higher than 40°C de-rating may be required (a simple rule is to de-rate by 0.5 % per degree centigrade). The voltage rating is not dependent upon ambient temperature.

A: The I²t value of a fuse is a measure of the energy which is required to open the fuse element and to interrupt the current. It is determined by factors such as the design of the fuse element, the type of filler, etc. The I²t value is also a direct measure for the let-through energy which is exposed to the item being protected by the fuse in case of an over-current situation. It is a function of current squared and time, hence it is expressed in A²s (amps x amps x seconds).

A: Semiconductor fuses are fuses that have been specifically designed to protect semiconductor devices. They are often also referred to as solid state fuses, rectifier fuses or ultra-rapid fuses. Semiconductor devices are extremely sensitive to current fluctuations and require special protection. To perform this function, semiconductor fuses are able to open the circuit (blow) significantly quicker than other fuse types, and it is extremely important that they are replaced by direct equivalents when required. Semiconductor fuses belong to the utilisation categories aR, gR and gS.

A: Semiconductor fuses are not selected like other fuse types. The main selection criteria for a semiconductor fuse is its I²t value…. even more important than its current rating! This is because semiconductor devices are extremely sensitive to current fluctuations and the maximum amount of let-through energy that they are exposed to during an over-current needs to be accurately controlled. This is super-important when selecting fuse protection for semiconductor devices.

A: When a current passes through a fuse, a small amount of energy is dissipated due to the fuse’s resistance. This can depend on the type of material used in the fuse’s element design, the quality of the filler, the amount of ceramic in the fuse body, etc. The amount of heat dissipated by a fuse is expressed in terms of ‘power dissipation’ also known as ‘watts loss’ and is measured in Watts. The maximum power dissipation for each type/rating is specified in the IEC Standards.

A: The material for the fuse wire must be a conductor. It should have a low melting point, such that when excess current passes through it, it melts down and breaks the circuit, hence stopping the current.

A: The rating of a fuse is always preceded by a letter on the metal casing. For example:T250ma or F210maThe “T” stands for “timed blow” (slow blow), and the “F” stands for “fast blow”.

A: Always disconnect equipment from electrical power before removing a fuse; not doing so may result in serious injury. Always replace a fuse with an identical type, and never substitute a fuse with foil or another object. This could lead to electrocution and fires.

A: Be sure the power is off in the circuit and the circuit is discharged before replacing a fuse. Use an identical replacement fuse if possible. Remove any corrosion from the fuseholder before replacing the fuse. Be certain the fuse properly fits the fuseholder.

A: Unscrew the damaged fuse and replace it with a fuse of the exact same size, amperage, and type.

A: The instrument cluster fuse manages the dashboard gauge of a vehicle. It uses electricity from the car battery to power various electronic components of the dashboard such as the different warning lights, gauges, and alarm systems. They include but are not limited to the following: Speedometer.

A: Available in a range of sizes from 1 Amp to 13 Amp. 3A fuses are colour coded red, 13A fuses are colour coded brown, all other fuse ratings are coloured black.