Protecting high-voltage DC power grids

Paul Boughton

Littelfuse has introduced the 487 Series Fuse, the first fast-acting fuse from its 5x20mm fuse family with both 420VAC and 420VDC ratings.

In contrast with existing fuse solutions that cannot meet high-voltage and short-circuit test requirements, the 487 Series protects telecom power supply units and datacenter server power applications where a high-voltage DC interrupting rating is required. 

This compact ceramic body fuse is designed to ensure the best co-ordination between a power supply unit (PSU) and an electrical circuit breaker panel during short-circuit and over-current faults.

The air circuit breaker trips before the fuse opens when the circuit is exposed to a short-circuit condition. When installed in a PSU, the 487 Series fuse opens faster than the circuit breaker in an electrical panel, removes the problematic PSU from the branch circuit, and keeps the branch circuit live without cutoff. 

The 487 Series’ 420VAC characteristics make it suited for high-energy applications like 3-phase power supplies, inverters, and ballasts. Its 420VDC characteristics make it an optimal choice for a high-voltage DC power grid in datacentres, telecom, and intelligent commercial buildings.