ASTM D6097-01
(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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NOTICE: This standard has either been superseded and replaced by a new version or discontinued.
Contact ASTM International (www.astm.org) for the latest information.
Designation: D 6097 – 01 An American National Standard
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 3.1.3 thickness of point-to-plane specimen (L), n—the ver-
tical distance in millimetres from the tip of the conical defect
1.1 This test method covers the relative resistance to vented
to the opposite surface of the solid dielectric material.
water-tree growth in solid non-black thermoplastic or
crosslinked electrical insulating materials. This test method is
4. Summary of Test Method
especially applicable to extruded polymeric insulation materi-
4.1 Ten compression-molded disc specimens, each contain-
als used in medium voltage power cables.
ing a conical-shaped defect, are subjected to an applied voltage
1.2 The values given in SI units are to be regarded as the
of 5 kV at 1 kHz and 2362°C in an aqueous conductive
standard.
solution of 0.01 N NaCl for 30 days. This controlled conical
1.3 This standard does not purport to address all of the
defect is created by a sharp needle with an included angle of
safety concerns, if any, associated with its use. It is the
60° and a tip radius of 3 μm. The electrical stress at the defect
responsibility of the user of this standard to establish appro-
tip is enhanced and can be estimated by the Mason’s Hyper-
priate safety and health practices and determine the applica-
6
bolic point-to-plane stress enhancement equation. This en-
bility of regulatory limitation prior to use. For specific hazard
hanced electrical stress initiates the formation of a vented
statements see 8.1.
water-tree grown from the defect tip. Each treed specimen is
1.4 There is no similar or equivalent IEC standard.
stained and sliced. The water-tree length and point-to-plane
2. Referenced Documents specimen thickness measured under microscope are used to
calculate a ratio that is defined as the resistance to water-tree
2.1 ASTM Standards:
2
growth.
D 1898 Practice for Sampling of Plastics
D 1928 Practice for Preparation of Compression-Molded
5. Significance and Use
3
Polyethylene Test Sheets and Test Specimens
5.1 This is a laboratory test designed to simulate the growth
D 2275 Test Method for Voltage Endurance of Solid Elec-
of vented water-trees in the solid dielectric insulating material
trical Insulating Materials Subjected to Partial Discharges
4
initiated by a sharp protrusion at the insulating and conductive
(Corona) on the Surface
interface under a wet environment in a high electrical field.
D 3756 Test Method for Evaluation of Resistance to Elec-
Water-treeing is the phenomenon which describes the appear-
trical Breakdown by Treeing in Solid Dielectric Materials
5 ance of tree-like growth in organic dielectrics under an ac field
Using Diverging Fields
when exposed to moist environments. Two types of water-trees
3. Terminology are formed. Bow tie trees (within the dielectric) and vented
water-trees formed from conductive/insulating material inter-
3.1 Definitions of Terms Specific to This Standard:
face into the insulating material. The water-trees referred to in
3.1.1 water tree length (WTL), n—a maximum distance, in
this test are the vented type. The insulating material is the solid
millimetres, of a path which is a tree-like micro-channel
dielectric organic material. The conductive material is the salt
measured parallel to the electric field from the axis of the tip of
solution. This salt solution is used on both sides of the
the conical defect.
insulating material to simulate the same inner and outer
3.1.2 resistance to water-tree growth (RWTG)— a dimen-
semiconductive shields saturated with moisture between the
sionless value which is L divided by the WTL.
insulation layer used in a medium-voltage underground power
cable.
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 May 10, 2001. Published July 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 – 97a. Dow Corning RTV Catalyst S, and the sealant, Dow Corning Multipurpose Silicone
2
Discontinued; see 1997 Annual Book of ASTM Standards, Vol 08.01. Sealant 732, known to the committee at this time is Dow Corning, Inc., Midland, MI
3
Annual Book of ASTM Standards, Vol 08.01. 48686. If you
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