Why Choose the Mersen AJT20 Class J Time-Delay Fuse?
The Mersen AJT20 is a high-performance Class J time-delay fuse engineered to protect industrial and commercial electrical circuits against overloads and short circuits. Part of the established Amp-Trap 2000® AJT series, it combines excellent current limitation with time-delay characteristics suited to equipment that produces temporary starting or energisation currents.
Designed for mains, feeders and branch circuits, the AJT20 can protect motors, transformers, control panels, lighting systems, heating equipment and general-purpose loads. Its time-delay response allows normal motor-starting and transformer inrush currents to pass while maintaining dependable protection against sustained overcurrent conditions.
With a rated current of 20 A, a UL-listed voltage rating of 600 V AC and a 400 V DC rating, the AJT20 is suitable for demanding power distribution and industrial control applications. It also features Mersen’s SmartSpot® visual open-fuse indicator, helping maintenance personnel identify an operated fuse quickly.
Key Advantages
- Dependable Class J time-delay protection for industrial circuits.
- 20 A current rating for motors, transformers and general loads.
- UL-listed for systems up to 600 V AC.
- Self-certified for applications up to 700 V AC.
- Superior current limitation reduces peak let-through current during faults.
- Compact design requires approximately half the mounting space of comparable 600 V Class RK fuses.
Key Features
- Mersen Amp-Trap 2000® AJT series.
- 20 A current rating.
- 600 V AC UL-listed rating.
- 700 V AC self-certified rating.
- 400 V DC rated voltage.
- Class J time-delay construction.
- SmartSpot® visual blown-fuse indication.
- Fibreglass body for dimensional stability in harsh environments.
- High-grade silica filler for rapid arc quenching.
- Unique Class J dimensions help prevent incorrect fuse replacement.
Reliable Protection for Industrial Electrical Systems
The AJT20 is engineered to withstand typical motor-starting and transformer inrush currents without unnecessary operation. Its carefully controlled time-delay characteristics help improve system continuity while ensuring that sustained overloads and short circuits are interrupted effectively.
During severe fault conditions, the fuse’s current-limiting design restricts peak let-through current and fault energy. This helps reduce thermal and mechanical stress on conductors, contactors, switchgear and downstream equipment, supporting improved system safety and reduced equipment damage.
Typical Applications
- Motor branch circuits and motor control centres.
- Transformer primary and secondary protection.
- Industrial mains and feeder circuits.
- Control panels and automation equipment.
- Lighting and heating circuits.
- Power distribution boards and load centres.
- Circuit-breaker back-up protection.
- Bus duct and general industrial loads.
