ASTM D6097-01a
(Test Method)Standard Test Method for Relative Resistance to Vented Water-Tree Growth in Solid Dielectric Insulating Materials
Standard Test Method for Relative Resistance to Vented Water-Tree Growth in Solid Dielectric Insulating Materials
SCOPE
1.1 This test method covers the relative resistance to vented water-tree growth in solid translucent thermoplastic or cross-linked electrical insulating materials. This test method is especially applicable to extruded polymeric insulation materials used in medium-voltage cables.
1.2 The values given in SI units are to be regarded as the standard.
1.3 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitation prior to use. For specific hazard statements see 8.1.
1.3 There is no similar or equivalent IEC standard.
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An American National Standard
Designation:D6097–01a
Standard Test Method for
Relative Resistance to Vented Water-Tree Growth in Solid
1
Dielectric Insulating Materials
This standard is issued under the fixed designation D 6097; 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.
1. Scope 3.1.2 resistance to water-tree growth (RWTG)— a dimen-
sionless value which is L divided by the WTL.
1.1 This test method covers the relative resistance to vented
3.1.3 thickness of point-to-plane specimen (L), n—the ver-
water-tree growth in solid translucent thermoplastic or cross-
tical distance in millimetres from the tip of the conical defect
linked electrical insulating materials. This test method is
to the opposite surface of the solid dielectric material.
especially applicable to extruded polymeric insulation materi-
als used in medium-voltage cables.
4. Summary of Test Method
1.2 The values given in SI units are to be regarded as the
4.1 Ten compression-molded disk specimens, each contain-
standard.
ing a conical-shaped defect, are subjected to an applied voltage
1.3 This standard does not purport to address all of the
of 5 kV at 1 kHz and 23 6 2°C in an aqueous conductive
safety concerns, if any, associated with its use. It is the
solution of 1.0 N NaCl for 30 days. This controlled conical
responsibility of the user of this standard to establish appro-
defect is created by a sharp needle with an included angle of
priate safety and health practices and determine the applica-
60° and a tip radius of 3 µm. The electrical stress at the defect
bility of regulatory limitation prior to use. For specific hazard
tip is enhanced and can be estimated by the Mason’s Hyper-
statements see 8.1.
6
bolic point-to-plane stress enhancement equation. This en-
1.4 There is no similar or equivalent IEC standard.
hanced electrical stress initiates the formation of a vented
2. Referenced Documents water-tree grown from the defect tip. Each treed specimen is
stained and sliced. The water-tree length and point-to-plane
2.1 ASTM Standards:
2
specimen thickness measured under microscope are used to
D 1898 Practice for Sampling of Plastics
calculate a ratio that is defined as the resistance to water-tree
D 1928 Practice for Preparation of Compression-Molded
3
growth.
Polyethylene Test Sheets and Test Specimens
D 2275 Test Method for Voltage Endurance of Solid Elec-
5. Significance and Use
trical Insulating Materials Subjected to Partial Discharges
4 5.1 This is a laboratory test designed to simulate the growth
(Corona) on the Surface
of vented water-trees in the solid dielectric insulating material
D 3756 Test Method for Evaluation of Resistance to Elec-
initiated by a sharp protrusion at the insulating and conductive
trical Breakdown by Treeing in Solid Dielectric Materials
5 interface under a wet environment in a high electrical field.
Using Diverging Fields
Water-treeing is the phenomenon which describes the appear-
3. Terminology ance of tree-like growth in organic dielectrics under an ac field
when exposed to moist environments.Two types of water-trees
3.1 Definitions of Terms Specific to This Standard:
are formed. Bow tie trees (within the dielectric) and vented
3.1.1 water tree length (WTL), n—the maximum length of a
water-trees formed from conductive/insulating material inter-
stained tree-like micro-channel path in millimetres, measured
face into the insulating material. The water-trees referred to in
from the tip of the conical defect in the direction of the conical
this test method are the vented type. The insulating material is
axis.
the solid dielectric organic material.The conductive material is
the salt solution. This salt solution is used on both sides of the
insulating material to simulate the same inner and outer
1
This test method is under the jurisdiction of ASTM Committee D09 on
Electrical and Electronic Insulating Materials and is the direct responsibility of
Subcommittee D09.12 on Electrical Tests.
6
Current edition approved Sept. 10, 2001. Published November 2001. Originally The sole source of supply of the base, Dow Corning 3110RTV, the catalyst,
published as D 6097 – 97. Last previous edition D 6097 – 01. Dow Corning RTVCatalyst S, and the sealant, Dow Corning Multipurpose Silicone
2
Discontinued; see 1997 Annual Book of ASTM Standards, Vol 08.01. Sealant732,knowntothecommitteeatthistimeisDowCorning,Inc.,Midland,MI
3
Annual Book of ASTM Standards, Vol 08.01. 48686. If you are aware of alternative suppliers, please provide this information to
4
Annual Book of ASTM Standards, Vol 10.01. ASTM International Headquarters.
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