Dissipation factor and ESR
– Electrical potential energy is dissipated in all dielectric materials, usually in the form of heat.
– A capacitor made of a dielectric placed between conductors includes a lossless ideal capacitor in series with a resistor called the equivalent series resistance (ESR).
– The ESR represents losses in the capacitor.
– In a good capacitor, the ESR is very small, and in a poor capacitor, the ESR is large.
– The ESR is not simply the resistance measured across a capacitor by an ohmmeter.
– The ESR is a derived quantity with physical origins in both the dielectric’s bulk conductivity and dipole relaxation phenomena.
– For the case of conduction electrons being the dominant loss, the ESR is given by ESR = σ / (εω^2C), where σ is the dielectric’s bulk conductivity, ε is the lossless permittivity of the dielectric, ω is the angular frequency of the AC current, and C is the lossless capacitance.
– A real capacitor has a lumped element model of a lossless ideal capacitor in series with an ESR.
– The loss tangent is defined by the angle between the capacitor’s impedance vector and the negative reactive axis.
– The loss tangent is often expressed as a percentage.
Power factor and DF
– The loss tangent approximates the power factor when the ESR is far less than Xc, which is usually the case.
– The power factor is often denoted as DF (dissipation factor).
– DF will vary depending on the dielectric material and the frequency of the electrical signals.
– In low dielectric constant ceramics, a typical DF of 0.1-0.2% is observed.
– In high dielectric constant ceramics, DF can be 1-2%.
Quality indicators
– Lower DF is usually an indication of quality capacitors when comparing similar dielectric materials.
– The quality of capacitors can be evaluated by comparing the DF values.
– DF is influenced by the dielectric material and the frequency of the electrical signals.
– Capacitors with lower DF values are generally preferred.
– DF can be used as a quality indicator for capacitors.
Related concepts
– Dielectric withstand test is a test to determine the ability of a dielectric material to withstand electrical stress without breaking down.
– Impulse generator is a device used to generate high-voltage electrical impulses.
– Basic Considerations: DF, Q, and ESR is a reference source providing information about DF, quality factor (Q), and equivalent series resistance (ESR).
– S. Ramo, J.R. Whinnery, and T. Van Duzer’s book ‘Fields and Waves in Communication Electronics’ is a recommended resource for understanding electromagnetic fields and waves in communication electronics.
Categorization and resources
– Dissipation factor is categorized under electromagnetism, electrical engineering, and dynamical systems. Source: https://en.wikipedia.org/wiki/Dissipation_factor
In physics, the dissipation factor (DF) is a measure of loss-rate of energy of a mode of oscillation (mechanical, electrical, or electromechanical) in a dissipative system. It is the reciprocal of quality factor, which represents the "quality" or durability of oscillation.
