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An operating temperature is the temperature at which an electrical or mechanical device operates. The device will operate effectively within a specified temperature range which varies based on the device function and application context, and ranges from the minimum operating temperature to the maximum operating temperature (or peak operating temperature). Outside this range of safe operating temperatures the device may fail. Aerospace and military-grade devices generally operate over a broader temperature range than industrial devices; commercial-grade devices generally have the narrowest operating temperature range. It is one component of reliability engineering. Although biological systems do not have a defined operating temperature, individuals are most comfortable when body temperature fluctuations as a result of environmental factors are minimised. ==Ranges== Devices are manufactured in several grades. For example, the manufacturer Altera defines five temperature grades for its products, each with an associated normal operating temperature range: *Commercial: 0°C to 85°C *Industrial: −40°C to 100°C *Automotive: −40°C to 125°C *Extended: −40°C to 125°C *Military: −55°C to 125°C These grades ensure that a device is suitable for its application, and may withstand the environmental conditions in which it is used. Normal operating temperature ranges are affected by several factors, such as the power dissipation of the device. These factors are used to define a ''threshold temperature'' of a device, that is its maximum normal operating temperature, and a maximum operating temperature beyond which the device will no longer function. Between these two temperatures, the device will operate at a non-peak level. For instance, a resistor may have a threshold temperature of 70 °C and a maximum temperature of 155 °C, between which it exhibits a thermal derating. For electrical devices, the operating temperature may be the junction temperature (TJ) of the semiconductor in the device. The junction temperature is affected by the ambient temperature, and for integrated circuits, is given by the equation: : in which TJ is the junction temperature in °C, Ta is the ambient temperature in °C, PD is the power dissipation of the integrated circuit in W, and Rja is the junction to ambient thermal resistance in °C/W. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Operating temperature」の詳細全文を読む スポンサード リンク
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