Overview
The Ferraz Shawmut A70QS450-4 is a 450A 700V high-speed semiconductor fuse in the Amp-Trap series, engineered for protection of advanced power conversion equipment. This fuse delivers fast-acting, current-limiting performance for dynamic solid-state applications where standard fuses cannot provide adequate response time. The A70QS series represents industry-standard protection for modern industrial drives and power systems.
Key Features
- High-speed, extremely fast-acting response for semiconductor protection
- Current-limiting design reduces fault energy and equipment stress
- 700V AC/DC dual voltage rating for flexible deployment
- 40 kA interrupting rating with Form 101 Type 4 bolted construction
- UL and CSA approved for commercial and industrial applications
- Proven Amp-Trap technology for motor drives, UPS, and variable frequency drives
Technical Specifications
- Rated Current: 450 Amperes
- Voltage Rating: 700 VAC / 700 VDC
- Interrupt Rating: 40 kA
- Fuse Speed: High Speed (aR)
- Fuse Class: Semiconductor (Form 101)
- Shape: Type 4, Bolted
- Dimensions: 2″ diameter × 5.09″ length (50.8mm × 129.29mm)
- Weight per Fuse: 1.19 lbs
- Approvals: UL, CSA
- Quantity per Box: 2 fuses
Typical Applications
- AC and DC motor drive protection (variable frequency drives, soft starters)
- Uninterruptible power supply (UPS) systems
- Reduced voltage motor starters and reduced acceleration starters
- Solid-state power conversion equipment with fast fault response requirements
- Renewable energy inverters and battery management systems
- Heavy industrial equipment requiring high I²t current limiting
Compatibility & Replacements
Compatible With
- Motor control centers (MCCs) rated 700V AC/DC
- Industrial frequency converters and variable frequency drives (VFDs)
- Uninterruptible power supplies (UPS) with 700V input
- Soft starters and reduced voltage motor starters
- Any equipment using Form 101 Type 4 bolted fuse holders rated for 700V semiconductor protection
Replaces / Drop-In Replacement For
- A70QS450 (alternative designation)
- Mersen A70QS450-4 (current manufacturer name)
- Direct replacement for legacy Ferraz Shawmut A70QS 450A fuses (verify holder compatibility)
Works With
- Form 101 Type 4 bolted fuse holders and clips
- Semiconductor fuse protection circuits rated for aR (fast-acting) fuses
- DC and AC circuits up to 700 volts
- Equipment designed for current-limiting semiconductor fuse technology
- Industrial electrical systems following NEC, IEC, and UL standards
