ASTM D1711-99

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Designation: D 1711 – 99 An American National Standard
Standard Terminology Relating to
Electrical Insulation
This standard is issued under the fixed designation D 1711; 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 (e) indicates an editorial change since the last revision or reapproval.
INTRODUCTION
This terminology is used in connection with testing and specifying solid electrical insulating
materials. Modifications to this terminology, reflecting common usage, may appear in particular test
methods, material specifications, practices, or other standards. Included herein are terms pertinent to
general applications, electrical insulating papers, mica, mica processing, processed mica forms,
hookup wire insulation, and partial discharge (corona).
1. Scope D 149 Test Method for Dielectric Breakdown Voltage and
Dielectric Strength of Electrical Insulating Materials at
1.1 This terminology is a compilation of technical terms
Commercial Power Frequencies
used in conjunction with testing and specifying solid electrical
D 150 Test Methods for AC Loss Characteristics and Per-
and electronic insulating materials in standards under the
mittivity Dielectric Constant of Solid Electrical Insulation
jurisdiction of Committee D-9 on Electrical and Electronic
D 3426 Test Method for Dielectric Breakdown Voltage and
Insulating Materials.
Dielectric Strength of Solid Electrical Insulating Materials
1.2 It is intended that all definitions in this terminology are
Using Impulse Waves
identical to definitions of the same terms as printed in standards
D 3636 Practice for Sampling and Judging Quality of Solid
of originating technical subcommittees, with the exceptions of:
Electrical Insulating Materials
(1) deletion of any part of the Discussion included in another
2.2 Other Standards:
standard that refers specifically to the use of a term in that
ANSI/ASQC A2-1987
standard; (2) figure numbers and corresponding references; and
(3) in this terminology, a parenthetical addition of a reference
3. Terminology
to one or more technical standards in which the term is used
acceptable quality level (AQL), n—the maximum percent
and the year in which the term was added to this compilation.
1.3 Symbols may be included as part of the representation nonconforming which, for purposes of sampling inspection,
can be considered satisfactory as a process average.
of terms, where appropriate.
1.4 It is not intended that this terminology include descrip- acceptance number, n—the maximum allowable number of
nonconformities for a given AQL and sample size (lot-
tions of terms or symbols (except as noted in 1.3). Acronyms
and abbreviations referring directly to defined terms may be sample size).
air chain, n—in mica, a series of air inclusions in the form of
included.
1.5 Revisions and additions to the definitions in this termi- a chain or streak.
arc propagation, n—the movement of an electric arc from its
nology are to be made as a product of a collaborative effort
between Subcommittee D09.94 and the various technical point of inception to another location. (1996) D 3032
arc tracking, n—the process producing tracks when arcs occur
subcommittees of Committee D-9, with Subcommittee D09.94
providing editorial advice to the technical subcommittees. New on or close to the insulation surface.
Arrhenius plot, n—a graph of the logarithm of thermal life as
definitions and revision of existing definitions must first be
approved by the cognizant technical subcommittee (or subcom- a function of the reciprocal of absolute temperature.
mittees) before inclusion in this terminology.
DISCUSSION—This is normally depicted as the best straight line fit,
determined by least squares, of end points obtained at aging tempera-
2. Referenced Documents
tures. It is important that the slope, which is the activation energy of the
2.1 ASTM Standards:
degradation reaction, be approximately constant within the selected
temperature range to ensure a valid extrapolation.
This terminology is under the jurisdiction of ASTM Committee D-9 on
Electrical and Electronic Insulating Materials and is the direct responsibility of Annual Book of ASTM Standards, Vol 10.01.
Subcommittee D09.94 on Editorial. Annual Book of ASTM Standards, Vol 10.02.
Current edition approved Oct. 10, 1999. Published November 1999. Originally Available from American National Standards Association, 11 W. 42nd St., 13th
published as D 1711 – 60 T. Last previous edition D 1711 – 98. Floor, New York, NY 10036.
Copyright © ASTM, 100 Barr Harbor Drive, West Conshohocken, PA 19428-2959, United States.
D 1711
ash content of paper, n—the solid residue remaining after surface current between two electrodes (on or in a specimen)
combustion of the paper under specified conditions, ex- to the dc voltage applied to the two electrodes.
pressed as a percentage of the dry mass of the original paper.
DISCUSSION—Insulation conductance is the reciprocal of insulation
(1996) D 202
resistance.
average discharge (corona) current (I ), n—the sum of the
t
conductance, surface, n—the ratio of the current between two
absolute magnitudes of the individual discharges during a
electrodes (on the surface of a specimen) to the dc voltage
certain time interval divided by that time interval.
applied to the electrodes.
DISCUSSION—When the discharges are measured in coulombs and the
DISCUSSION—(Some volume conductance is unavoidably included in
time interval in seconds, the calculated current will be in amperes.
the actual measurement.) Surface conductance is the reciprocal of
t
surface resistance.
Q 1 Q 1222222 Q
( 1 2 n
t
I 5 (1)
t conductance, volume, n—the ratio of the current in the
t 2 t
1 0
volume of a specimen between two electrodes (on or in the
where:
specimen) to the dc voltage applied to the two electrodes.
I 5 average current, A,
t
DISCUSSION—Volume conductance is the reciprocal of volume resis-
t 5 starting time, s,
tance.
t 5 completion time, s, and
Q ,Q ,Q 5 partial discharge quantity in a corona pulse
1 2 n conducting material (conductor), n—a material within which
1 through n,C.
an electric current is produced by application of a voltage
between points on, or within, the material.
binder tape—see core wrap (binder tape).
bond strength, n—a measure of the force required to separate
DISCUSSION—The term “conducting material” is usually applied only
surfaces which have been bonded together. (1996) to those materials in which a relatively small potential difference results
in a relatively large current since all materials appear to permit some
D 2519, D 3145, D 4882
conduction current. Metals and strong electrolytes are examples of
braid, n—(1) woven metallic wire used as a shield for
conducting materials.
insulated conductors and cables.
(2) A woven fibrous protective outer covering over an
conductivity, surface, n—the surface conductance multiplied
insulated conductor or cable. by that ratio of specimen surface dimensions (distance
breakdown voltage—see dielectric breakdown voltage. between electrodes divided by the width of electrodes
bursting strength of paper, n—the hydrostatic pressure re-
defining the current path) which transforms the measured
quired to produce rupture of a circular area of the material conductance to that obtained if the electrodes had formed the
under specified test conditions. (1996) D 202
opposite sides of a square.
cable wrap, n—paper used for mechanical protection or for
DISCUSSION—Surface conductivity is expressed in siemens. It is
space-filling (rather than as electrical insulation) in low-
popularly expressed as siemens/square (the size of the square is
voltage cables with nonmetallic sheaths.
immaterial). Surface conductivity is the reciprocal of surface resistivity.
capacitance, C, n—that property of a system of conductors
conductivity, volume, n—the volume conductance multiplied
and dielectrics which permits the storage of electrically
by that ratio of specimen volume dimensions (distance
separated charges when potential differences exist between
between electrodes divided by the cross-sectional area of the
the conductors.
electrodes) which transforms the measured conductance to
DISCUSSION—Capacitance is the ratio of a quantity, q, of electricity to
that conductance obtained if the electrodes had formed the
a potential difference, V. A capacitance value is always positive. The
opposite sides of a unit cube.
units are farads when the charge is expressed in coulombs and the
potential in volts:
DISCUSSION—Volume conductivity is usually expressed in siemens/
centimetre or in siemens/metre and is the reciprocal of volume
C 5 q/V (2)
resistivity.
capacitor tissue, n—very thin (5 to 50 μm) pure, nonporous
conductor, n—a wire, or combination of wires not insulated
paper used as the dielectric in capacitors, usually in conjunc-
from each other, suitable for carrying electric current. (1996)
tion with an insulating liquid.
D 1676
coating powder, n—a heat-fusible, finely-divided solid resin-
continuous partial discharges (continuous corona),
ous material used to form electrical insulating coatings.
n—discharges that recur at rather regular intervals; for
(1996) D 2967, D 3214
example on approximately every cycle of an alternating
concentricity, n—the ratio, expressed in percent, of the mini-
voltage or at least once per minute for an applied direct
mum wall thickness to the maximum wall thickness.
voltage.
concentric-lay conductor, n—a conductor composed of a
core wrap (binder tape), n—paper used to wrap groups of
central core surrounded by one or more layers of helically
insulated wire into cable configuration prior to sheathing.
laid strands.
DISCUSSION—Usually, this term is applied to telephone communica-
DISCUSSION—In the most common type of concentric-lay conductor,
tion cables in which core wrap is not regularly subjected to voltage
all strands are of the same size and the central core is a single strand.
stress, but may be exposed to surges from lightning strokes or other
conductance, insulation, n—the ratio of the total volume and accidental events.
D 1711
corona, n—visible partial discharges in gases adjacent to a shortened to “breakdown voltage.”
conductor.
dielectric constant—see relative permittivity.
DISCUSSION—This term has also been used to refer to partial dielectric failure (under test), n—an event that is evidenced
discharges in general.
by an increase in conductance in the dielectric under test
limiting the electric field that can be sustained.
critical property, n—a quantitatively measurable characteris-
dielectric strength, n—the voltage gradient at which dielectric
tic which is absolutely necessary to be met if a material or
failure of the insulating material occurs under specific
product is to provide satisfactory performance for the
conditions of test.
intended use.
dip encapsulation (a type of conformal coating), n—an
DISCUSSION—In some situations, specification requirements coincide
embedding process in which the insulating material is
with customer usage requirements. In other situations, they may not
applied by immersion and without the use of an outer
coincide, being either more or less stringent. More stringent sampling
container.
(for example, smaller AQL values) is usually used for measurement of
characteristics which are considered critical. The selection of sampling
DISCUSSION—The coating so formed generally conforms with the
plans is independent of whether the term defect or nonconformity is
contour of the embedded part.
appropriate.
dissipation factor (loss tangent) (tan d), D, n—the ratio of
cross grains or reeves, n—in mica, tangled laminations
the loss index to its relative permittivity or
causing imperfect cleavage.
D5k9/k8 (3)
crude mica—mica as mined; crude crystals with dirt and rock
adhering.
It is also the tangent of its loss angle, d, or the cotangent
crystallographic discoloration, n—in mica, discoloration ap-
of its phase angle, u. (See Fig. 1 and Fig. 2.)
pearing as bands of lighter or darker shades of basic color of
DISCUSSION—a:
a block of mica. (1996)
D 5 tand5 cotu5 X /R 5 G/vC 5 1/vC R (4)
p p p p p
DISCUSSION—Such bands are generally parallel to the crystallo-
graphic faces of the crystal from which the block was separated.
where:
G 5 equivalent ac conductance,
defect, n—a departure of a quality characteristic from its
X 5 parallel reactance,
p
intended level, or state, that occurs with a severity sufficient
R 5 equivalent ac parallel resistance,
p
to cause an associated product or service not to satisfy
C 5 parallel capacitance, and
p
intended normal, or reasonably foreseeable, usage require-
v5 2pf (sinusoidal wave shape assumed).
ments.
The reciprocal of the dissipation factor is the quality factor, Q,
DISCUSSION—The terms “defect” and “nonconformity” and their
sometimes called the storage factor. The dissipation factor, D,ofthe
derivatives are used somewhat interchangeably in the historical and
capacitor is the same for both the series and parallel representations as
current literature. Nonconformity objectively describes the comparison
follows:
of test results to specification requirements, while the term defect has a
D5vR C 5 1/vR C (5)
connotation of predicting the failure of a product or service to perform
s s p p
The relationships between series and parallel components are as follows:
its intended function in use. Since this latter connotation is often
unintended, the term nonconformity is preferred in full consensus
C 5 C / 1 1 D (6)
~ !
p s
standards. The selection of any sample plan is independent of whether
2 2 2 2
the term defect or nonconformity is appropriate. R /R 5 1 1 D !/D 5 1 1 1/D ! 5 l 1 Q
~ ~
p s
The term defect may be appropriate for specifications mutually DISCUSSION—b: Series Representation—While the parallel represen-
agreed upon by a producer and a user where specific use conditions are tation of an insulating material having a dielectric loss (Fig. 3) is
clearly understood. Even in these cases however, use the term defect usually the proper representation, it is always possible and occasionally
with caution and consider substituting the term nonconformity. desirable to represent a capacitor at a single frequency by a capacitance,
For additional comments, see ANSI/ASQC A2-1987 that also states: C , in series with a resistance, R (Fig. 4 and Fig. 2).
s s
“When a quality characteristic of a product or service is “evaluated” in
drainage, n—of an insulating varnish, a measure of the
terms of conformance to specification requirements, the use of the term
variation in thickness fro
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