Equivalent series inductance (ESL) is an effective
inductance
Inductance is the tendency of an electrical conductor to oppose a change in the electric current flowing through it. The flow of electric current creates a magnetic field around the conductor. The field strength depends on the magnitude of th ...
that is used to describe the inductive part of the
impedance of certain electrical components.
Overview
The theoretical treatment of devices such as
capacitor
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of ...
s and
resistor
A resistor is a passive two-terminal electrical component that implements electrical resistance as a circuit element. In electronic circuits, resistors are used to reduce current flow, adjust signal levels, to divide voltages, bias active e ...
s tends to assume they are ''ideal'' or "perfect" devices, contributing only capacitance or resistance to the
circuit. However, all physical devices are connected to a circuit through conductive leads and paths, which contain inherent, usually unwanted, inductance. This means that physical components contain some inductance in addition to their other properties.
[{{Cite book, last=Maniktala, first=Sanjaya, url=https://books.google.com/books?id=zMVTv6py7woC&dq=%22Equivalent+series+inductance%22&pg=PA631, title=Switching Power Supplies A - Z, date=2012-04-18, publisher=Elsevier, isbn=978-0-12-386533-5, pages=631, language=en]
An easy way to deal with these inherent inductances in circuit analysis is by using a
lumped element model
The lumped-element model (also called lumped-parameter model, or lumped-component model) simplifies the description of the behaviour of spatially distributed physical systems, such as electrical circuits, into a topology consisting of discrete e ...
to express each physical component as a combination of an ideal component and a small
inductor
An inductor, also called a coil, choke, or reactor, is a passive two-terminal electrical component that stores energy in a magnetic field when electric current flows through it. An inductor typically consists of an insulated wire wound into a c ...
in
series
Series may refer to:
People with the name
* Caroline Series (born 1951), English mathematician, daughter of George Series
* George Series (1920–1995), English physicist
Arts, entertainment, and media
Music
* Series, the ordered sets used in ...
, the inductor having a value equal to the inductance present in the non-ideal, physical device.
Effects
Ideally, the
impedance of a
capacitor
A capacitor is a device that stores electrical energy in an electric field by virtue of accumulating electric charges on two close surfaces insulated from each other. It is a passive electronic component with two terminals.
The effect of ...
falls with increasing frequency at 20 dB/decade. However, due partly to the inductive properties of the connections, and partly to non-ideal characteristics of the capacitor material, real capacitors also have inductive properties whose impedance ''rises'' with frequency at 20 dB/decade. At the ''resonance frequency'' the sum of both is minimal, above it the
parasitic series inductance of the capacitor dominates.
See also
*
Equivalent series resistance
Practical capacitors and inductors as used in electric circuits are not ideal components with only capacitance or inductance. However, they can be treated, to a very good degree of approximation, as being ideal capacitors and inductors in series w ...
(ESR)
References
Electrical parameters
Capacitors