8. SPD Types: Type 1, 2 & 3 · Page 6 of 7
Pluggable Cartridges vs Fixed SPDs
Maintenance philosophy drives the mechanical choice.

Pluggable
Faster replacement without rewiring. Ideal for facilities that cannot tolerate long outages.
Fixed
Sometimes preferred for compact or cost-sensitive boards, but replacement means more labor.
Stocking
If you standardize on a cartridge family (like Protec DIN-rail lines), keep spares on site before monsoon / storm season.
