Slide 1 - Stewart Superabsorbents

Recommended Test Methods for
Underground Power Cables
Containing Superabsorbent
Kenneth E. Bow, Kable Consult LLC and
Richard M. Ellis, Cable Materials Inc.
• Growth in Use of Underground Cables
• Use of Water Blocking Materials to Control
Longitudinal and Radial Water Flow
• Prevent Growth of Water Trees
• SAP – Superabsorbent Materials Are Used in
Sheath and Conductor to Block Water
• SAP Materials in the Form of Powders or
Encapsulated in Fabrics, Tapes and Yarns
Objective of This Paper
• Propose a Modified Test Method and Test
Media to Predict the Service Performance and
Life of Water Blocked Underground Power
• Propose Test Requirements that More
Adequately Reflect Field Conditions
• Propose a Path to Harmonization of ICEA and
IEC Test Standards
Use of SAP Materials in Cable
• Use of Powders and Yarns to Block the Flow of
Water Between the Wires in the Conductor
• Use of Semiconducting Tapes to Block Water
around the Conductor
• Use of Semiconducting Tapes to Block Water
in the Core-Metallic Shield Interface
• Use of Semiconducting or Non-Conducting
Tapes in the Metallic Shield-Jacket Interface
Properties of SAP Materials
• Absorption and Retention of a Certain
Quantity of Water
• Absorption Speed to Quickly Stop the Flow of
• High Permeability of the Hydrated SAP to
Prevent the Capillary Transport of Water
• Resistance to Hydrolysis and Gel Degradation
over the Service Life of the Cable
Water Penetration Testing –
State of the Art
• SAP with Rapid Swell Speed/Large Capacity
• Distilled or De-ionized Water/Tap Water
• Longitudinal Application of a Water Head to
the End of the Cable – Test of Conductor
• Application of Water at a 90 Degree Angle –
the “Tee” Test – Test of Sheath Interfaces
• Wide Variability on Test Duration, Water Type,
Temperature and Thermal Cycling
Proposed New Test Media
• Standard Ionic Solution Based on ASTM
D1141 – 98(2013) “Standard Practice for
the Preparation of Substitute Ocean Water”
Blend of 3% of Ocean Water and 97% Distilled
Represents Soil Water with Effectively a 0.1%
Ionic Solution
Proposed Standardized Test Method
for Swell Height of SAP Materials
• Use Method Specified in CENELEC HD 605 S2
Section 2.5.9
• “Cup and Ram” Type of Swell Test
• Eliminates Variations from One Vendor or User
to Another
• Meets Need for a Standardized ICEA Test
Standardize the Test Media as an Ionic Solution
• Standardize the Swell Cup Test Method
• Standardize the Cable Water Penetration Test
Method to Include Thermal Loading for Power
Cables at Operating Temperatures
• Method to Include Cable Operation at
Emergency Rated Temperature (ERT)
• Tests Must Reflect Service Conditions
Photograph of 69 kV Laminate Sheath

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