Cartridge Fuses

Electrical cartridge type fuses are low-cost electrical safety devices that are used for the overload protection of electrical circuits and appliances. They are cylindrical in shape and have a contact point at each end. Cartridge fuses are typically constructed from ceramic, glass, or porcelain.

RS stocks a comprehensive range of cartridge fuses from industry-leading brands including Eaton, Littelfuse, Mersen and of course RS PRO.

How Do Electrical Cartridge Fuses Work?

Cartridge fuses contain a piece of wire that melts when too much current flows through the circuit. When the wire melts, it breaks the circuit which prevents any damage. This is often referred to as burning out or blowing out. Put simply, when a fuse blows, the circuit is broken. Once a fuse has blown, it will need replacing to make the circuit complete again and allow the flow of current.

What Are the Different Types of Electrical Fuse Markings and Speed Codes?

Cylindrical cartridge fuses are used in a range of industrial, commercial, and domestic applications. Selecting the correct fuse speed is essential for the protection of your device. Here are some of the most common markings you will find on a cartridge fuse.

• FF = Very Fast Acting (Flink Flink): These electrical fuses are designed to blow very quickly when the current exceeds the rated value, providing immediate protection. They are ideal for protecting sensitive electronic components that require rapid response to overcurrent conditions.
• F = Fast Acting (Flink): Fast-acting electrical fuses blow quickly but not as instantaneously as very fast-acting fuses. They are used in applications where a moderate speed of response is adequate, such as in lighting circuits and some motor applications.
• M = Medium Acting (Mitteltrage): Medium-acting electrical fuses provide a balance between fast and slow response times. They are suitable for circuits where temporary surges are acceptable, but sustained overloads need to be prevented, such as in heating and motor control circuits.
• T = Slow Acting (Trage): Slow-acting electrical fuses, or time-delay fuses, can withstand temporary overloads without blowing, which makes them ideal for circuits with inrush currents, such as motor start-ups and inductive loads.
• TT = Very Slow Acting (Trage Trage): Very slow-acting electrical fuses are designed to tolerate longer periods of overcurrent before blowing. They are used in applications where long-duration overloads occur, providing protection for equipment that can handle brief overcurrent conditions.
• HRC = High Rupture Capacity Fuses: High rupture capacity (HRC fuses) is designed to handle high fault currents without exploding. These provide reliable protection in high-power industrial applications, ensuring safety and minimising damage during fault conditions.

Types of Electrical Fuse Materials

Fuse materials are selected based on their characteristics and the specific requirements of the applications they are used in. Here are some common types of fuse materials:

• Glass Cartridge Fuse: Glass tube cartridge fuses have a transparent body, allowing for easy inspection of the fuse element. They are commonly used in electronic devices and automotive applications due to their reliability and the ability to quickly identify a blown fuse. Various glass fuse sizes cater to different voltage and current ratings, making them versatile for numerous applications.
• Ceramic Fuse: Ceramic fuses are known for their high interrupting rating and durability under harsh conditions. They can withstand higher temperatures and have better arc-quenching properties than glass fuses. Ceramic fuse sizes vary, allowing them to be used in a wide range of high-power applications, including industrial and commercial settings.
• Plastic Fuse: These electrical fuses are lightweight and often used in consumer electronics. Plastic fuses provide a cost-effective solution and are typically found in applications where high interrupting ratings are not necessary.
• Fibreglass Fuse: Fibreglass fuses offer excellent thermal stability and mechanical strength. They are used in environments where resistance to high temperatures and mechanical stress is required. These fuses are ideal for industrial and heavy-duty applications.
• Metal Fuse: Metal-bodied fuses, often made from aluminium or other alloys, provide robust protection and are used in high-current applications. Their metal construction offers excellent durability and heat dissipation, making them suitable for demanding industrial environments.

Why Use Cartridge Fuses?

Cartridge fuses are a relatively cheap way of protecting electrical equipment from short circuits and overcurrent. They are incredibly safe as they do not produce flames, arcs, or gas when they burn out and break the circuit.

What Current Rating Should You Choose?

Electrical fuses are available in a range of standard amperages. When choosing a fuse for your application, it is essential to select one with a nominally higher current rating than the device it is being used in. This ensures that slight, harmless power increases will not cause the fuse to blow. Here are the key types of ratings to consider:

• Current Rating: The current rating of an electrical fuse is the maximum amount of current it can handle without breaking. Choose one with a current rating that matches or slightly exceeds the maximum current expected in the circuit to prevent unnecessary interruptions.
• Voltage Rating: The voltage rating indicates the maximum voltage the electrical fuse can safely interrupt without causing damage. Always choose one with a voltage rating that meets or exceeds the voltage of your electrical system to ensure safe operation.
• Interrupting Rating: Also known as breaking capacity, the interrupting rating is the maximum fault current an electrical fuse can safely interrupt without causing damage. Ensure the interrupting rating of the fuse you choose is adequate for your specific application to protect against high fault currents.

Industrial Applications for Electrical Fuses

Electrical fuses are crucial components in various industrial settings, ensuring the safety and reliability of electrical systems. Here are some key industry applications of electrical fuses:

• Manufacturing: Cartridge type fuses are used to protect machinery and equipment from overcurrent conditions. They ensure smooth operation by preventing damage to motors and controllers due to electrical faults.
• Automotive: Glass cartridge fuses are commonly used in automotive electrical systems to protect circuits and components from short circuits and overloads. They are essential for maintaining the safety and functionality of vehicle electrical systems.
• Telecommunications: In telecommunications, fuse electrical components protect sensitive equipment from power surges and faults. Ceramic fuses are often used in these scenarios, selected for their durability and high interrupting capacity.
• Power Generation: Electrical fuses in power generation systems safeguard generators, transformers, and distribution panels from overcurrent and short-circuit conditions. High rupture capacity (HRC) fuses are particularly important in these high-power environments.
• HVAC Systems: Glass tube fuses are used in heating, ventilation, and air conditioning systems to protect against overcurrent conditions. They ensure reliable operation and prevent damage to HVAC equipment.
• Consumer Electronics: Glass cartridge fuses are widely used in consumer electronics to protect delicate components from electrical faults. Their transparency allows for easy inspection and replacement when needed.

Buying Electrical Fuses: Ordering & Delivery

RS is a trusted supplier and distributor of a comprehensive range of electrical fuses, including glass tube fuses, plastic fuses, ceramic fuses, cartridge type fuses, and more. We stock a variety of industry-leading brands such as: ABB, Schneider Electric, Omron, and our in-house brand, RS PRO.

To place an order online, simply browse our extensive catalogue, where you can filter and select your preferred products based on your specifications. RS Singapore offers fast delivery of timer relays. For more details on delivery services and fees, please refer to our Delivery Page.