Overview
The Bussmann FRS-R-12 is a Class RK5 time-delay fuse engineered for industrial electrical protection. This dual-element, current-limiting fuse features a 12 A rating with an interrupting rating of 200 kA at 600 Vac and 20 kA at 300 Vdc. Unlike fast-acting fuses, the FRS-R-12 allows inrush currents during motor start-up without nuisance blows, while still responding quickly to genuine fault conditions.
Key Features
- Dual-element, current-limiting, time-delay fuse with energy-efficient design
- Delivers 8 seconds minimum time-delay at 500% of rated current (for 1/10–30A sizes)
- Voltage Rating: 600VAC / 250VDC; Size: 20.6mm × 127mm (13/16″ × 5″)
- Non-indicating design—no open fuse indicator
- 200 kA interrupting rating at 600 Vac—suitable for industrial panel-board applications
- Provides motor-running back-up and current-limiting protection in one cartridge
Technical Specifications
- Fuse Current: 12A
- Voltage Rating (AC): 600VAC
- Voltage Rating (DC): 250VDC / 300VDC
- Class: RK5
- Type: Time-Delay (Dual-Element)
- Interrupting Rating: 200 kA @ 600VAC; 20 kA @ 300VDC
- Physical Size: 0.81″ diameter × 5″ length (20.6mm × 127mm)
- Weight: 3.2 oz
- Body: Ceramic with ferrule terminals
- Approvals: UL, CSA, CE
- Series: FRS-R (Fusetron)
- Configuration: Cartridge (Rejection-type holder mount)
Typical Applications
The FRS-R-12 is commonly used in:
- Industrial motor control circuits—protects against overloads and short circuits without nuisance trips during motor inrush
- Machine tool and pump motor feeders
- Control transformer secondary circuits
- Power distribution panels rated 600V and below
- OEM equipment builders designing UL-listed electrical systems
Compatibility & Replacements
Compatible With
- Class RK5 rejection-type fuse holders and clips (standard cartridge configuration)
- Industrial control panels, switchboards, and distribution equipment
- Motor starters and overload protection relays (as a coordinated protection layer)
- Equipment rated for 600VAC, 250VDC service
- UL/CSA-listed industrial electrical systems
Replaces / Drop-In Replacement For
- Older Bussmann/Fusetron FRS-R-12 units (direct replacement, same cartridge and terminal type)
- Littelfuse FLSR equivalent (verify application compatibility with your system integrator)
- Mersen TRS-R series equivalent (recommend testing for your specific application)
Works With
- All Class RK5 certified fuse holders and rejection-type clips
- Motor control centers (MCCs) and combination starters
- Industrial power distribution and panelboard systems
- Coordinated protection schemes with relays and breakers
