Goals and Symptoms

Solid State Relay: Operating limitation in altitude

Facts and Changes

SSR
altitude

Causes and Fixes

Altitude is a factor in heat dissipation capability.
All heat dissipation capacities in data sheet are usually based on an altitude of 3300 feet (1000 meters) or less.
At higher altitudes, air density, fan efficiencies, and heat transfer efficiencies all decrease.
Usual derating of heat dissipation capacity of the heatsink, is 2% for each additional 1000 feet (305 meters) above the 3300 feet (1000 meters).