0.25A 250V Glass Cartridge Fuse 5 x 20mm

0.25A Glass Fuse (5 x 20mm) is a fundamental circuit protection component designed to provide reliable overcurrent safety for a wide variety of electronic appliances. This specific 250mA rated fuse is engineered to bridge the gap between low-current signal protection and standard power supply safeguarding. Consequently, it serves as a critical defense mechanism by melting its internal element almost instantaneously when current levels exceed the safe 0.25 Ampere limit. Therefore, integrating the 0.25A Glass Fuse into your design ensures that downstream components remain shielded from destructive short circuits or prolonged thermal overloads. Furthermore, its standardized 5 x 20mm cylindrical form factor guarantees seamless compatibility with an extensive range of fuse holders, clips, and blocks found in both consumer and industrial hardware. Indeed, this component offers a cost-effective yet highly efficient solution for preventing permanent damage to sensitive PCB traces and expensive integrated circuits. Briefly, it delivers consistent electrical performance and peace of mind for engineers and hobbyists alike.

Key Features:

• Fast-Acting Protection: Optimized for a rapid response, this fuse clears the circuit within milliseconds of a fault, consequently protecting delicate semiconductor components from high-energy surges.
• High-Visibility Glass Body: Featuring a transparent glass tube, the component allows for immediate visual inspection, enabling users to quickly identify a blown fuse without needing additional testing equipment.
• Low Internal Resistance: Engineered with a high-conductivity alloy element, the fuse maintains a low voltage drop across its terminals, therefore minimizing energy loss and heat generation during normal operation.
• Universal Form Factor: The 5 x 20mm size is globally recognized as the standard for miniature cartridge fuses, ensuring easy replacement and availability for international electronics.
• Durable Construction: Built with nickel-plated brass end caps, it resists environmental corrosion and ensures a secure, low-resistance electrical contact throughout the lifespan of the device.

0.25A Glass Fuse Technical Specifications:

• Rated Current (I_N): 0.25 A (250 mA)
• Rated Voltage (V_N): 250 V_AC / 125 V_DC
• Breaking Capacity: 35 A @ 250 V_AC (Low Breaking Capacity Profile)
• Fuse Characteristic: Fast-Acting (F)
• Operating Temperature Range: −55°C to +125°C (Continuous Duty)
• Typical Resistance (R_DC): Approximately 0.6 Ω to 1.5 Ω

Mechanical Specifications:

• Body Material: High-Strength Transparent Glass Tube
• End Cap Material: Nickel-Plated Copper or Brass Alloys
• Internal Fuse Element: Multi-Alloy Metallic Wire
• Package Type: Standard Miniature Cartridge
• Device Marking: F250mAL250V (F for Fast, 250mA for Current, 250V for Voltage)

Dimensions:

• Diameter (D): 5.0 mm (±0.2 mm)
• Length (L): 20.0 mm (±0.5 mm)
• Industry Standard: IEC 60127-2/3 (Miniature Fuse Standard)

Pinout and Wiring:

• Safety Function: This fuse operates as a two-terminal series protection component.
• Connection 1: Attach one ferrule end to the incoming current path (input rail).
• Connection 2: Connect the opposite ferrule end to the protected equipment (load side).
• Wiring Note: Additionally, for maximum safety, always mount the fuse on the “Hot” side of the AC line before it reaches the main power transformer or switching regulator.

Datasheet Reference:

• Download 0.25A Glass Fuse Datasheet (GMA Series)

Commonly Used in:

• Bench Power Supplies: Protecting the secondary output stages of variable voltage regulators.
• Industrial Control Boards: Safeguarding the control power transformrs and low-voltage relay logic.

Applications:

• Adapter Protection: Implementing a primary safety layer for small AC-to-DC wall adapters and battery chargers.
• Instrumentation: Specifically, shielding the internal circuitry of signal generators and frequency counters.
• Smart Home Devices: Enhancing the safety of connected thermostats and gateway controllers.

Equivalent Models:

• Bussmann GMA-250mA: A standard high-reliability equivalent widely used in industrial power electronics.
• Bel Fuse 5SF 250-R: A drop-in replacement that meets all relevant electrical safety standards.
• Littelfuse 217.250: A fast-acting variant offering precise breaking characteristics for sensitive hardware.

Package Includes:

• 1 x 0.25A 250V Glass Cartridge Fuse (5 x 20mm)