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D3555-20 – Standard Test Method Technical Guide
📐 Scope and Material Specifications
This standard, designated D3555-20, specifies the requirements for a track-resistant crosslinked polyethylene (XLPE) insulation intended for wire and cable applications with a maximum continuous conductor temperature of 90 °C. The base polymer must substantially consist of polyethylene or its copolymers.
The insulation compound is required to be carbon black pigmented or suitably colored to provide ultraviolet (UV) stability, making it ideal for outdoor exposure. This insulation is designed for use in overhead spaced-line power transmission service, where it is installed at temperatures above −25 °C and exposed to atmospheric environments ranging from −55 °C to +90 °C.
A critical technical note in the scope states that tests performed on insulated wire are conducted solely to determine the relevant properties of the insulation material itself, rather than the conductor or completed cable assembly.
⚠️ Composition Requirement: The insulation must be carbon black pigmented or colored and suitably protected to enable UV stability for sustained outdoor performance.
⚙️ Physical Property and Aging Requirements
The insulation must meet strict physical, electrical, and aging requirements. The standard defines “aging” as the exposure of materials to air at a temperature of 121 °C for 168 hours. Testing for physical properties, aging effects, heat distortion, cold bend, U-bend discharge, surface resistivity, and track resistance is performed in accordance with Test Methods D470.
Additionally, the material must comply with specific requirements for percent hot creep and hot set, evaluated in accordance with ICEA T-28-562. In the event of a dispute, the solvent extraction method specified in Test Methods D2765 (Gel Content and Swell Ratio) serves as the official referee method for determining the degree of crosslinking.
💡 Dispute Resolution Method: While hot creep testing per ICEA T-28-562 is the primary requirement, the solvent extraction (Gel Content and Swell Ratio) tests per D2765 are designated as the referee standard for resolving disputes.
📊 Key Test Methods and Performance Criteria
The following table outlines the primary property requirements and their corresponding test methods.
| 🟦 Property | 📏 Test Method | 🎯 Performance Condition / Requirement |
|---|---|---|
| Aging (Thermal) | D470 | 121 °C for 168 h in air |
| Heat Distortion | D470 | Shall meet specified requirements |
| Cold Bend | D470 | Shall meet specified requirements |
| U-Bend Discharge | D470 | Shall meet specified requirements |
| Surface Resistivity | D470 | Shall meet specified requirements |
| Track Resistance | D470 / D2132 | Shall meet specified track & erosion resistance |
| Hot Creep / Hot Set | ICEA T-28-562 | Shall meet specified percentages |
| Gel Content / Swell Ratio | D2765 | Referee standard for dispute resolution |
❓ Frequently Asked Questions
🔍 What is the maximum continuous conductor temperature for this insulation?
The insulation is considered suitable for continuous operation at conductor temperatures up to 90 °C.
💡 How does the standard define “aging” for track-resistant XLPE?
Aging is specifically defined as the exposure of the insulation material to air at a temperature of 121 °C for a duration of 168 hours.
⚡ What test is cited for evaluating the track resistance property?
Track resistance is evaluated in accordance with Test Methods D470 and the dust-and-fog tracking test outlined in Test Method D2132.
📌 What are the environmental temperature limits for installation and service?
This insulation is suitable for installation at temperatures above −25 °C and can withstand exposure to atmospheric environments between −55 °C and +90 °C.