Customizable Thermal Switches

A military helicopter experienced an over-temp indication from a thermal switch while flying a mission in a sand storm. The warning light was blinking. The crew landed the helicopter aborting their part of the mission. Failure analysis revealed a competing switch that closed intermittently. The military came to Honeywell to develop a switch which could sense the temperature without being effected by vibration near the set-point. The diameter of the hole the switch had to fit in was smaller than the ½” switch diameter. Honeywell developed a thermal nail that threaded in the hole, thermally isolated the switch from the exterior, and developed an accurate thermal offset to control the temperature reliably in all environments. The fleet was subsequently retrofitted.

Years later a large US commercial aircraft manufacturer needed a small probe diameter thermal switch for reasons of high vibration, space limitations, and high temperature. The thermal nail concept was applied along with unique mounting configuration, short probe length, and the same process of temperature development used earlier leading to a satisfactory use on the aircraft fleet.

These devices are in production now. Honeywell can tailor a thermal switch solution to fit your needs. Contact us to customize the right solution for you.

Thermal switches exported from the United States must be done in accordance with the export administration regulations (EAR) and/or the international traffic in arms regulations (ITAR) as applicable.