Solenoid (Coil)

Life of the Solenoid depends on ambient temperature, duty cycle, temperature rise and class of insulation used for the solenoid. Temperature rise depends on design, current density and insulation system of the coil. Rotex ensures that for all its design of the coil, temperature rise above ambient is less than 70 °C

As per IS 4800 standard, insulation system is designed for minimum life of for 20000 Hours When used continuously. Using the half life decay principle, every 10 °C reduction of the coil temperature, twice the life can be extra polated. Considering worst temperature rise of the coil at 1.2 times the rated voltage, continuously energized coil shall be less than 70 °C. For a ambient temperature of 55 °C, the maximum temperature of the coil will be 55 + 70 = 125 °C
For a Solenoid having class F insulation minimum life expected shall be as under:
20000 Hours at 155 °C
40000 Hours at 145 °C
80000 Hours at 135 °C
160000 Hours at 125 °C

Which means, Life of a Continuously energized Solenoid having Class F Insulation, i.e. (ambient of 55 °C) is Minimum of 160000 Hrs ie 18 Yrs.

In case if more life is expected then Solenoid with better insulation or lower temperature rise is to be used (e.g. Low Power Solenoid)