ST550-4

Overview

The ST550-4 is a high-speed semiconductor fuse manufactured by Mersen, designed for the protection of sensitive electronic components such as IGBTs and thyristors. It features a ceramic body with silver-plated copper end caps and a nickel-plated brass stud mounting configuration. The device is rated for 690V AC and 1000V DC, with a current rating of 550A and a breaking capacity of 100kA RMS symmetrical. It utilizes a spring-loaded mechanism to ensure reliable contact pressure during operation.

Feature Summary

• High-speed interruption capability for protecting sensitive power electronics
• Spring-loaded stud mounting design ensures consistent contact pressure
• Ceramic body construction provides robust mechanical and thermal stability
• Silver-plated contacts minimize resistance and enhance conductivity

Applications

• Protection of IGBT modules in industrial drives
• Circuit protection for thyristor-based converters
• DC link protection in renewable energy inverters
• Railway traction drive systems

Procurement Notes

Verify the specific voltage and current ratings against the application requirements before procurement. Confirm that the mounting stud dimensions match the available busbar or terminal interface. Ensure the breaking capacity exceeds the prospective short-circuit current at the installation point. Check for any required accessories such as torque specifications or compatible mounting hardware.

Selection Notes

Select this component based on its ability to clear faults rapidly to protect downstream semiconductor devices. Consider the ambient temperature derating curves provided in the official datasheet. Evaluate the physical space constraints for the stud-mounted configuration. Compare the let-through energy (I²t) values against the withstand capabilities of the protected components.

Part Context

This part belongs to Mersen's range of high-performance fuses intended for industrial power applications. It is distinct from general-purpose fuses due to its specialized fast-acting characteristics. The series is engineered for harsh environments common in heavy industry and transportation sectors.

Replacement Considerations

When substituting this part, verify that the replacement has identical electrical ratings and physical mounting dimensions. Ensure the new fuse offers equal or superior breaking capacity and let-through energy performance. Consult official cross-reference lists from Mersen or authorized distributors for confirmed equivalent part numbers.