Dissipation factor

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In physics, the dissipation factor (DF) is a measure of loss-rate of power of a mechanical mode, such as an oscillation, in a dissipative system.

For example, electric power is lost in all dielectric materials, usually in the form of heat. DF is expressed as the ratio of the resistive power loss to the capacitive power, and is equal to the tangent of the loss angle.

It is also referenced as the loss tangent

tan d,

and approximate power factor.

In capacitors, DF is the ratio of a capacitor's equivalent series resistance (R) to its capacitive reactance (Xc). DF is usually expressed as a percentage.

    DF = (R/Xc) × 100% = R/(1/ωC) × 100% = ωRC × 100%

where ω is the angular frequency (2πf).

DF will vary depending on the dielectric material. In low dielectric constant (K), temperature compensating, ceramics DF of 0.1 to 0.2% is typical. In high dielectic constant ceramics, DF can be 1 to 2%. However, lower DF is usually an indication of quality capacitors when comparing similar dielectric material.