Why Choose the Mersen HSJ20 High-Speed Class J Fuse?
The Mersen HSJ20 is a 20 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 recognised Class J circuit-protection performance with the rapid operation required by modern industrial power electronics.
The HSJ20 is suitable for circuits containing variable frequency drives, electronic motor controllers, rectifiers, inverters, UPS equipment and solid-state switching devices. Its current-limiting construction helps reduce peak fault current and let-through energy during severe short-circuit conditions, helping protect vulnerable components and minimise equipment damage.
Rated at 20 A, 600 V AC and 500 V DC, the Mersen HSJ20 offers a compact protection solution for industrial control panels and power-conversion systems. Its Class J rejection-style configuration helps prevent the installation of incompatible fuse classes in a suitable fuse holder or fuse block.
Key Advantages
- Combines Class J branch-circuit and semiconductor protection.
- 20 A rated current for industrial control and power-electronic circuits.
- Suitable for systems rated up to 600 V AC or 500 V DC.
- High-speed operation helps protect sensitive semiconductor components.
- Current-limiting performance reduces peak fault current and let-through energy.
- Class J rejection dimensions help prevent incorrect fuse substitution.
Key Features
- Mersen Amp-Trap® HSJ series.
- 20 A nominal current rating.
- 600 V AC and 500 V DC voltage ratings.
- High-speed Class J operating characteristic.
- Low I²t performance for semiconductor protection.
- Current-limiting fuse construction.
- Designed to tolerate normal drive and motor-controller operating conditions.
- Suitable for compatible Class J fuse holders and fuse blocks.
Fast Protection for Sensitive Power Electronics
Power-semiconductor devices may be damaged by fault energy before a conventional general-purpose fuse has time to operate. The Mersen HSJ20 uses a high-speed fuse element and low-I²t design to interrupt severe faults rapidly, limiting the thermal and electrical stress applied to connected equipment.
Its Class J construction also provides branch-circuit protection and rejection-style dimensional control. Correct selection should consider the system voltage, continuous operating current, temporary inrush current, available fault current and the protection recommendations supplied by the equipment manufacturer.
Typical Applications
- Variable frequency drives and motor-drive systems.
- Electronic motor controllers and soft starters.
- Industrial rectifiers, inverters and power converters.
- Uninterruptible power supply systems.
- Solid-state relays and semiconductor assemblies.
- Industrial control panels and OEM machinery.
