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Complete Guide to High Rupturing Capacity (HRC) Fuses

What are HRC Fuses?

High Rupturing Capacity (HRC) Fuses are manufactured in a wide variety of shapes, sizes and electrical specifications. All these different types of HRC fuses are designed to protect circuits in specific applications. The main defining factor of an HRC fuse is it's ability to safely stop an over-current in an electrical circuit and this over-current may be considerably higher than the normal operating current of the circuit. The reason an HRC fuse is able to safely stop a high over-current is primarly due to the materials and construction of the fuse rather than the internal fuse element, which determines the opening speed and normal current handling capability of the fuse. An HRC fuse must be replaced when it is blown.

HRC Fuses

HRC Fuse Construction

The main design elements that differentiate an HRC fuse from a Low Breaking Capacity (LBC) fuse are;

  • Heat resistant, strong outer fuse body, usually constructed from ceramic or fibreglass.
  • The cavity inside the fuse body is commonly filled with fine silica sand or quartz to absorb the heat and energy of an over-current.
  • The metal caps or tags are solidly affixed to the fuse body to create an air tight seal in order to prevent any energy escaping in the event of an overload occuring.

If we compare this with a LBC fuse like a glass body 3AG or M205 fuse. The glass body does not provide the strength of a cermamic body and it can fragment if the overload current is too high. There is no internal filling to absorb the heat and energy caused by an overload.

HRC fuse construction

HRC Fuse Element

The element of an HRC fuse is similar to that of a regular fuse. It is manufactured from a metal such as silver that is designed to melt at a predetermined temperature. When the fuse is operating within it's normal current range, the heat in the element is dissipated without causing any damage to the element. Should the current flowing through the fuse exceed the normal range, the element will overheat and melt in predetermined areas, causing the fuse to open so current will no longer pass through the fuse. The fuse will need to be replaced.

The design of the fuse element controls the electrical characteristics of the fuse, such as opening speed, fault tolerance, ampere and voltage handling capabilities.

Breaking Capacity of an HRC Fuse

A high breaking capacity or interrupting rating is one of the defining characteristics of an HRC fuse. The breaking capacity of the fuse is the maximum fault current that a fuse can safely interrupt in a circuit, expressed in amperes. Here is an example:

A glass M205 fuse (a LBC fuse) has an interrupting rating of 10 x rated current. The highest ampere rating we sell for an M205 fuse is 16A. Therefore a 16A fuse could safely protect the circuit from an overload current of 160A.

If we compare with a ceramic M205 HRC fuse, the interrupting rating is 1500A regardless of the ampere rating of the fuse. The ceramic M250 fuse can stop overloads nearly 10 times higher even though the physical size of the fuse and it's ampere & voltage rating are identical to the glass LBC fuse.

HRC Fuse Types and Applications

The majority of HRC fuses are built for use in industrial applications where cables and machinery require protection at higher voltages and amperages. HRC fuses are generally not required to protect low voltage / low ampere requirements of consumer electronics or automotive applications. Therefore the majority of HRC fuses are often rated at 415V or higher. Some of the most common HRC fuse types are DIN NH blade fuses, British Standard BS88 fuses and American or European cartridge fuses.

HRC Fuse Speeds and Sizes

HRC fuses are available in all element speeds ranging from semicondutor protection (very fast acting fuse) to motor protection (slow acting fuse). The following list illustrates the variety of fuse speeds available for DIN NH blade fuses. Learn more about fuse speeds.

  • Semiconductor fuse speeds: aR, gR, gS.
  • General Purpose fuse speeds: gG, gL, gF.
  • Slow Acting fuse speeds: aM, gM.
  • Special Purpose fuse speeds: gPV, gB, gTr.

The physical size of an HRC fuse can vary depending on it's intended application and voltage rating. HRC Fuses with higher voltage ratings generally have a longer body to reduce the likelyhood of arcing within the fuse. Some of the smaller, low voltage HRC cartridge fuses measure only 38mm in length, whilst medium voltage fuses can exceed 500mm in length.

Where Can I Buy HRC Fuses?

We stock a huge range of HRC fuses to suit different applications. See our product ranges for NH Blade Fuses, BS88 Fuses, American and European HRC fuses and purchase online or contact our friendly sales staff for assistance.

NH HRC Fuses for Sale

NH Fuses are a general purpose HRC fuse with a wide array of applications from protection of motors to solar pv and battery systems. They are identifiable from their rectangular ceramic casing enclosed by a cover plate that features a metal blade style terminal on each end. Learn more about NH Fuses.Some of the most common NH fuses are;

  Application Type NH Fuse Size
NH General Purpose Fuses NH General Purpose Fuses gL / gG 000 to 4a
NH Motor Protection Fuses NH Motor Protection Fuses aM 000 to 4a
NH Semiconductor Fuses NH Semiconductor Fuses 690V aR / gR 000 to 3
NH Semiconductor Fuses NH Semiconductor Fuses 1000V aR / gR 00 to 0
NH Solar PV Fuses NH Solar PV Fuses gPV 1 to 3
NH Battery Fuses NH Battery Fuses gS 000 to 3
NH Neutral Links NH Neutral Links - 00 to 4a

British Standard (BS88) HRC Fuses for Sale

BS88 fuses are commonly used in a wide variety of electrical circuits and typically feature a cylindrical ceramic casing with 2 metal tags or lugs designed to fix the fuse into a fuse holder using bolts. These BS88 fuses are available in semiconductor, fast acting or slow acting speeds and used in circuits ranging from 240V to 660V.

American Standard HRC Fuses for Sale

These HRC fuses are typically designed to various American standards and are available as cartridge fuses or bolt down tag type fuses. One of the more common American cartridge fuses is the 10 x 38mm fuse. These fuses are available for use in electrical circuits with a voltage rating of up to 1000V and fuse element speeds cover the full spectrum of semiconductor to slow acting.

European Semicondutor HRC Fuses for Sale

European HRC fuses are also available in cartridge or bolt down tag versions. Depending on the fuse, the ceramic body may be cylindrical, bottle shaped, square, rectangular and may even feature threaded ends. They are sold in a wide range of ampere and voltage ratings and also available in all the different element speeds.

Customer Feedback

" As always the service of your team was fantastic. I did not order all the components of the fuse block wanted as I already had them, however, your team held the order and contacted me immediately advising that there were more parts needed to make up the assembly (and provided the relevant part numbers and required quantities). I thought this was a great service as those not familiar with the process or the items could be left short and have to further wait for the additional parts. Keep an eye out as there will be more orders coming!! "

Stuart E
Received 7/6/23

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