Overview
The Bussmann Fusetron FRS-R-50 is a dual-element, time-delay Class RK5 fuse designed for reliable protection in industrial electrical systems. Rated at 50 amperes, 600V AC / 300V DC, it delivers 200kA interrupting capacity and meets UL standards for current-limiting applications. The time-delay design allows temporary motor inrush currents while responding quickly to sustained overcurrent and short-circuit faults, making it ideal for motor control centers, combination starters, and industrial panelboards.
Key Features
- Dual-element construction — Superior time-delay performance for motor branch circuits and transformer protection
- Class RK5 classification — 200kA RMS interrupting rating; UL-listed current-limiting fuse
- Ferrule terminals — Standard connection type for rejection-type fuse holders
- 10-second minimum response time at 500% rated current for reliable inrush tolerance
- Cylindrical fiberglass body — Durable, rejectable design prevents improper installation
Technical Specifications
- Ampere Rating: 50A
- Voltage Rating: 600V AC / 300V DC
- Fuse Class: RK5
- Interrupting Rating: 200 kA @ 600V; 20 kA @ 250V
- Response Type: Time-Delay (Dual-Element)
- Time-Delay Rating: 10 seconds (minimum) @ 500% rated current
- Body Diameter: 1.06 inches
- Overall Length: 5.50 inches
- Weight: 0.31 lb
- Terminal Type: Ferrule x Ferrule
- Material: Fiberglass cylindrical body
- Series: FRS-R
Typical Applications
- Motor branch circuits — Branch circuit protection for three-phase and single-phase motors with inrush tolerance
- Combination starters — Used in combination motor starters where both overload and short-circuit protection are required
- Motor control centers (MCCs) — Feeder and branch protection in industrial MCCs and panelboards
- Machinery disconnects — Machinery protection disconnects and industrial equipment enclosures
- Power distribution panelboards — Industrial feeder and main circuits up to 50A
- Transformer circuits — Primary protection for control transformers and power transformers
Compatibility & Replacements
Compatible With
- Standard rejection-type Class RK5 fuse holders (ferrule terminal configuration)
- Industrial motor control centers and combination starters
- Machinery disconnect switches rated for Class RK5 fuses
- Power panelboards and distribution equipment designed for RK5 fuses
- Equipment requiring 600V / 300V DC dual voltage capability
Replaces / Drop-In Replacement For
- Bussmann FRS-R-50 (direct equivalent)
- Cooper Bussmann FRS-R-50
- Eaton Bussmann FRS-R-50 (successor brand)
Works With
- Class RK5 rejection-type fuse holders (ferrule terminals)
- UL-listed industrial panelboards and motor control equipment
- Standard current-limiting applications in 600V distribution systems
- Motors, transformers, and industrial machinery requiring time-delay overcurrent protection
