Why Choose the Mersen HSJ25 High-Speed Class J Fuse?
The Mersen HSJ25 is a 25 A high-speed Class J fuse designed to provide branch-circuit protection while limiting the fault energy transferred to sensitive semiconductor equipment. Part of the Mersen Amp-Trap® HSJ series, it combines Class J circuit-protection performance with the rapid fault-clearing characteristics required by modern industrial power-electronic systems.
The HSJ25 is suitable for circuits containing variable frequency drives, electronic motor controllers, phase controllers, rectifiers, inverters and solid-state switching devices. Its low-I²t, current-limiting construction helps reduce peak fault current and thermal energy during short-circuit conditions, protecting vulnerable components and helping minimise equipment damage.
Rated at 25 A, 600 V AC and 500 V DC, the Mersen HSJ25 provides a compact protection solution for industrial control panels, machinery and power-conversion equipment. Its Class J configuration also helps prevent the installation of an incompatible fuse class when used with a suitable rejection-style fuse holder or fuse block.
Key Advantages
- Combines Class J branch-circuit and semiconductor protection.
- 25 A rated current for industrial control and power-electronic circuits.
- Suitable for systems rated up to 600 V AC or 500 V DC.
- Low-I²t performance helps reduce thermal stress on semiconductor devices.
- Current-limiting operation reduces peak fault current and let-through energy.
- Excellent cycling capability supports equipment with repeated operating cycles.
Key Features
- Mersen Amp-Trap® HSJ series.
- 25 A nominal current rating.
- 600 V AC and 500 V DC voltage ratings.
- High-speed Class J operating characteristic.
- Low let-through energy for semiconductor protection.
- Current-limiting fuse construction.
- Optimised overload capability for electronic motor-controller applications.
- Suitable for compatible Class J fuse holders and fuse blocks.
Fast Protection for Sensitive Power Electronics
Semiconductor devices such as SCRs, GTOs, diodes and solid-state relays can be damaged by fault energy before a conventional general-purpose fuse has time to operate. The Mersen HSJ25 uses a high-speed fuse element and low-I²t design to interrupt severe faults rapidly, limiting the electrical and thermal stress applied to connected equipment.
The fuse also provides Class J branch-circuit protection and is designed with overload capability suitable for electronic motor controllers. Correct fuse selection should consider the system voltage, continuous operating current, temporary inrush current, available fault current and the protection requirements specified by the equipment manufacturer.
Typical Applications
- Industrial branch circuits and control panels.
- Variable frequency drives and motor-drive systems.
- Electronic motor controllers and soft starters.
- Phase controllers and power-conversion equipment.
- Industrial rectifiers and inverters.
- Solid-state relays and semiconductor assemblies.
