Why Choose the Mersen A4BQ800 Class L Time-Delay Fuse?
The Mersen A4BQ800 is a high-performance Class L time-delay fuse engineered to protect industrial and commercial power distribution systems against damaging overloads and short-circuit currents. As part of the established Mersen Amp-Trap 2000® A4BQ series, it is suitable for mains, feeder circuits, large motors and other demanding high-current applications.
Mersen A4BQ fuses provide enhanced current limitation, helping reduce the peak current and energy passed through to downstream electrical equipment during a fault. This supports improved protection for conductors, switchgear, busbars and connected components while helping minimise thermal and mechanical damage.
Rated at 800 A, 600 V AC and 500 V DC, the A4BQ800 incorporates a built-in 4-second time-delay characteristic at 500% of rated current. This allows harmless temporary inrush currents from motors, transformers and other inductive loads to pass without nuisance fuse operation.
Key Advantages
- Dependable Class L time-delay protection for high-capacity electrical systems.
- 800 A current rating for demanding industrial distribution circuits.
- 600 V AC and 500 V DC voltage ratings.
- Amp-Trap 2000® technology provides enhanced current limitation.
- Time-delay performance accommodates normal motor and transformer inrush currents.
- Suitable for mains, feeders, large motors and circuit-breaker back-up protection.
Key Features
- Mersen Amp-Trap 2000® A4BQ series.
- 800 A rated current.
- 600 V AC rated voltage.
- 500 V DC rated voltage.
- Class L current-limiting time-delay fuse.
- 4-second time delay at 500% of rated current.
- 200 kA AC interrupting rating.
- 100 kA DC interrupting rating.
- 300 kA AC self-certified interrupting performance with UL-witnessed testing.
- Pure silver fuse links for low let-through current and dependable service life.
- Fibreglass body for dimensional stability in harsh industrial environments.
- High-grade silica filler supports rapid arc quenching.
- Rejection-style Class L design helps prevent replacement errors.
Advanced Protection for Industrial Power Distribution
The Mersen A4BQ800 is designed to operate rapidly during severe short-circuit conditions, limiting the current and clearing energy reaching downstream equipment. Its current-limiting construction can reduce let-through current and associated thermal stress compared with conventional Class L protection.
The fuse also provides time-delay performance for equipment with high start-up currents. This allows large motors, transformers and similar loads to start normally while maintaining dependable protection against sustained overloads and dangerous short-circuit faults.
Typical Applications
- Electrical mains and service entrance equipment.
- Industrial feeder circuits.
- Large motor circuits.
- Transformer-fed distribution systems.
- Lighting and heating loads.
- General industrial electrical loads.
- Circuit-breaker back-up protection.
- UPS DC links and battery disconnect circuits.
- Industrial switchgear and switchboards.
