FWH-400A FUSE BUSSMANN

FWH-400A FUSE BUSSMANN – High-Speed 400A 500VAC/VDC Bolt-On Semiconductor Fuse

The FWH-400A FUSE BUSSMANN (Model FWH-400A) is an industrial-grade, ultra-fast semiconductor protection fuse manufactured by Eaton’s Bussmann series. Engineered specifically to provide critical overcurrent, short-circuit, and thermal protection for high-power semiconductor devices—such as silicon-controlled rectifiers (SCRs), diodes, thyristors, and insulated-gate bipolar transistors (IGBTs)—this $400\text{-amp}$ , $500\text{ VAC/VDC}$ fuse delivers low thermal energy let-through across industrial power conversion equipment.

Featuring a Class aR high-speed operating profile, the FWH-400A FUSE BUSSMANN provides fast clearing action under severe electrical fault conditions. It delivers an interrupting capacity of $200\text{ kA RMS}$ Symmetrical at $500\text{ VAC}$ and $50\text{ kA}$ at $500\text{ VDC}$ . Constructed with a cylindrical ceramic body and heavy-duty bolted blade tags, it restricts peak thermal let-through energy ( $I^2t$ ), preventing catastrophic damage to sensitive solid-state power electronics.

As seen on the body label in the image, the fuse features a high-density white ceramic casing clearly printed with “FWH-400A 400A 500V ac/dc aR Bussmann® ASSEMBLED IN MEXICO” alongside the Bussmann brand logo, semiconductor diode/thyristor graphic symbol, and UL Recognized and CSA certification marks. It is fitted on both ends with pre-drilled slotted metal mounting blades for direct stud or busbar installation.

Key Features of the FWH-400A FUSE BUSSMANN

Ultra-Fast Semiconductor Protection: Designed with Class aR partial-range clearing characteristics to shield sensitive power semiconductors against damaging short circuits.
Dual $500\text{V}$ AC/DC Operating Voltage: Rated for continuous service in both $500\text{ VAC}$ and $500\text{ VDC}$ circuits, providing multi-system installation flexibility.
High $200\text{ kA}$ Interrupting Capacity: Safely interrupts high prospective short-circuit fault currents up to $200\text{ kAIC}$ at $500\text{ VAC}$ ( $50\text{ kAIC}$ at $500\text{ VDC}$ ).
Low Thermal Let-Through ( $I^2t$ ): Low pre-arcing ( $19,200\text{ A}^2\text{s}$ ) and total clearing $I^2t$ ( $96,700\text{ A}^2\text{s}$ at $500\text{V}$ ) reduce mechanical and thermal stress on downstream electronics.
Robust Bolt-On Blade Mounting: Includes solid slotted blade terminals that support direct stud mounting and low-resistance bolted busbar connections.
Durable Ceramic Body Construction: Built with a high-strength ceramic casing filled with high-purity arc-quenching silica sand to safely suppress internal high-energy arcing.

Common Applications and Practical Usage

The ultra-fast response, $400\text{A}$ power handling, and bolted-tag footprint of the FWH-400A FUSE BUSSMANN make it a core protective component across heavy industrial power systems:

Variable Frequency Drives (VFDs): Shields main AC drive input rectifiers, DC bus capacitors, and inverter modules.
DC Common Bus & Servo Drives: Protects industrial DC bus distribution networks, high-power servo amplifiers, and DC motor control drives.
Industrial Power Rectifiers: Protects high-current AC-to-DC rectifiers, heavy electroplating systems, and battery charging infrastructure.
Uninterruptible Power Supplies (UPS): Safely isolates static switches, main power inverters, and battery banks in utility-grade UPS installations.

Technical Specifications

The core electrical, physical, and compliance specifications for the FWH-400A FUSE BUSSMANN are detailed below:

Parameter Specification	Technical Details & Operational Values
Component Type	High-Speed Bolt-On Semiconductor Fuse
Primary Keyword	FWH-400A FUSE BUSSMANN
Brand / Series	Eaton Bussmann Series / FWH High-Speed
Catalog Model / Part No.	FWH-400A
Amperage Rating	$400\text{ Amps}$ RMS ( $400\text{A}$ )
Voltage Rating	$500\text{ VAC}$ / $500\text{ VDC}$
Interrupt Rating (IR)	$200\text{ kA RMS}$ Symmetrical at $500\text{ VAC}$ / $50\text{ kA}$ at $500\text{ VDC}$
Utilization Category	Class aR (Partial Range Semiconductor Protection)
Pre-Arcing $I^2t$	$19,200\text{ A}^2\text{s}$
Clearing $I^2t$ at $500\text{V}$	$96,700\text{ A}^2\text{s}$
Watts Loss at Rated Current	Approx. $65\text{ W}$
Terminal Connection Type	Bolt-On Slotted Metal Blade End Tags
Physical Dimensions	$38.1\text{ mm}$ $\times 110.2\text{ mm}$ Length ( $1.50'' \times 4.34''$ )
Agency Certifications	UL Recognized (File E56412/E91958), CSA Certified (File 53787), CE, RoHS

Operating Guidelines and Usage Tips

SAFETY NOTICE: Always isolate power supplies and verify the circuit is completely de-energized with a tested multi-meter before handling, inspecting, or replacing high-capacity power fuses.

Busbar Torque & Mounting: Secure blade terminals directly to copper busbars or fuse blocks using appropriate fasteners. Torque to specified manufacturer values to avoid localized thermal hotspots due to contact resistance.

Semiconductor Coordination: Ensure the total clearing energy ( $I^2t$ ) of the fuse is lower than the thermal withstand limit ( $I^2t$ ) of the semiconductor component being protected.

To review official semiconductor high-speed fuse standards and overcurrent protection specifications, consult the National Electrical Manufacturers Association (NEMA) Directory.

To check regional warehouse inventory availability or request commercial quotes for volume electrical fuses, visit the Control Qatar Contact Page.