ASTM A340-18

This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previous version. Because
it may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current version
of the standard as published by ASTM is to be considered the official document.
Designation: A340 − 17a A340 − 18
Standard Terminology of
1
Symbols and Definitions Relating to Magnetic Testing
This standard is issued under the fixed designation A340; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
In preparing this glossary of terms, terminology standard, an attempt has been made to avoid, where
possible, vector analysis and differential equations so as to make the definitions more intelligible to
the average worker in the field of magnetic testing. In some cases, rigorous treatment has been
sacrificed to secure simplicity, simplicity and clarity, but it is believed that none of the definitions will
prove to be misleading.
It is the intent of this glossary terminology standard to be consistent in the use of symbols and units
with those found in ANSI/IEEE 260-1978 and USA Standard Y 10.5-1968.IEC 60050-221:1990
International Electrotechnical Vocabulary Chapter 221: Magnetic materials and components. Although
Committee A06 has chosen to make SI units normative, the extensive technical and commercial
literature using the older Gaussian units requires that many definitions contain discussion about and
use of both unit systems. This is not an endorsement of the older unit system and users of this
terminology are encouraged to use SI units where possible.
Part 1—Symbols Used in Magnetic Testing
Symbol Term
α cross-sectional area of B coil
A cross-sectional area of specimen
A' solid area
B
magnetic flux density
H
magnetic induction
ΔB excursion range of induction
B · biased induction
b
B remanent induction
d
B remanence
dm
B H energy product
d d
(BH) maximum energy product
max
B incremental induction
Δ
B intrinsic induction
i
B intrinsic flux density
i
B maximum induction in a hysteresis loop
m
B maximum induction in a flux current loop
max
B residual induction
r
B retentivity
rs
B saturation induction
s
cf crest factor
CM cyclically magnetized condition
d lamination thickness
D demagnetizing coefficient
B
df distortion factor
D magnetic dissipation factor
m
E exciting voltage
E induced primary voltage
1
1
This terminology is under the jurisdiction of ASTM Committee A06 on Magnetic Properties and is the direct responsibility of Subcommittee A06.92 on Terminology
and Definitions.
Current edition approved Oct. 15, 2017June 1, 2018. Published October 2017July 2018. Originally approved in 1949. Last previous edition approved in 2017 as
A340 – 17.A340 – 17a. DOI: 10.1520/A0340-17A.10.1520/A0340-18.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
1

---------------------- Page: 1 ----------------------
A340 − 18
E induced secondary voltage
2
E flux volts
f
f cyclic frequency in hertz
^ magnetomotive force
ff form factor
H magnetic field strength
ΔH excursion range of magnetic field strength
H biasing magnetic field strength
b
H coercive field strength
cB
H intrinsic coercive field strength
cJ
H demagnetizing field strength
d
H incremental magnetic field strength
Δ
H air gap magnetic field strength
g
H ac magnetic field strength (from an assumed
L
peak value of magnetizing current)
H maximum magnetic field strength in a hyster-
m
esis loop
H maximum magnetic field strength in a flux-
max
current loop
H ac magnetic field strength (from a measured
p
peak value of exciting current)
H instantaneous magnetic field strength (coinci-
t
dent with B )
max
H ac magnetic field strength force (from an as-
z
sumed peak value of exciting current)
H ac magnetic field strength (from an assumed
z
peak value of exciting current)
I ac exciting current (rms value)
I ac core loss current (rms value)
c
I constant current
dc
I ac magnetizing current (rms value)
m
J magnetic polarization
k' coupling coefficient
! flux path length
! effective flux path length
1
! gap length
g
+ (also φ N ) flux linkage
+ mutual flux linkage
m
L self inductance
L core inductance
1
L incremental inductance
Δ
L intrinsic inductance
i
L mutual inductance
m
L initial inductance
0
L series inductance
s
L winding inductance
w
m magnetic moment
M magnetization
m total mass of a specimen
m active mass of a specimen
1
N demagnetizing factor
D
N turns in a primary winding
1
N turns in a secondary winding
2
N I/! ac excitation
1 1
p magnetic pole strength
3 permeance
P active (real) power
P apparent power
a
P specific
...