the ability of a given thickness of a substance to prevent heat transfer.

The measure of a material’s ability to resist heat flow. The formula for Thermal Resistance is R = L / k where (L) is the material’s thickness and (k) is the material’s Thermal Conductivity constant. The higher a material’s R-value, the better it insulates, and conversely. For more information, click here.

(R-value) - A property of a substance or construction which retards the flow of heat; one measure of this property is R-value.

An indication of how effectively a unit rids itself of heat; a measure of temperature rise per watts lost. In Powertec Indusrtrial Motors literature, it is the specified value from the motor windings to the ambient, under locked rotor conditions.

The ability of a material to slow the transfer of heat energy from a hot environment to a colder one.

The property of a material, device or system that impedes the flow of heat. The symbol for thermal impedance is Qxy , where x is the physical point from which heat flows and y is the physical point to which heat flows. Thermal impedance is defined as the temperature difference between two specified points or regions divided by the power dissipation under conditions of thermal equilibrium.

A measure of the heat transfer capacity of the LED. Lower resistance is preferred.

The reciprocal of the time rate of heat flow through a unit area induced by a unit temperature difference between two defined surfaces of material or construction under steady-state conditions. (h x ft² x °F/Btu) [(m² x K)/W].

An index of a material's resistance to heat flow. See R and RSI.

Resistance to heat flow. The reciprocal of conductance (C).

The reciprocal of thermal conductance.

temperature rise per unit of power loss.

Under steady conditions, the mean temperature difference between two defined surfaces of material or construction that induces unit heat flow through unit area. Note

The resistance of various materials to the passage of heat energy. Most electrical conductors are also thermal conductors, with the higher electrical conductivity materials usually having higher thermal conductivity. Important in the design of high power electronics, heatsinks, semiconductor casings, etc.

This designates the resistance of a material to heat conduction. The greater the R-value the larger the number.