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 electric current produces a magnetic field around the conductor. The magnetic field strength depends on the magnitude of the ...
that is used to describe the inductive part of the
impedance of certain electrical components.
Overview
The theoretical treatment of devices such as
capacitor
In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term st ...
s and
resistor
A resistor is a passive two-terminal electronic 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 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 Passivity (engineering), passive two-terminal electronic component, electrical component that stores energy in a magnetic field when an electric current flows through it. An inductor typic ...
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 i ...
, the inductor having a value equal to the inductance present in the non-ideal, physical device.
Effects
Ideally, the
impedance of a
capacitor
In electrical engineering, a capacitor is a device that stores electrical energy by accumulating electric charges on two closely spaced surfaces that are insulated from each other. The capacitor was originally known as the condenser, a term st ...
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 (ESR)
References
Electrical parameters
Capacitors