Description

Elsewedy 3-Core Aluminum Indoor Terminations, 12/20 kV

Introduction: Engineering Aluminum Connections in Medium-Voltage Environments

A termination is one of the most critical components in a power-cable system: it is the point where the cable shielding system ends and the cable connects to distribution equipment. At12/20 kV, and withaluminumconductors, the connection is not merely metal-to-metal contact; it is a complex engineering process requiring careful management of electrical stress and metal oxidation. Elsewedy indoor heat-shrink terminations are designed to provide a robust transition from an aluminum cable to switchgear or transformers, while resisting indoor operating conditions such as heat, moisture, and carbon dust.

Chapter One: Engineering Structure and Electrical Stress-Control System

Elsewedy terminations use advanced radiation-crosslinked polymer technology and consist of several technical layers working together:

1. Stress Control System

Once the cable semiconductive layer is cut, electric-field lines become concentrated at the termination point, which can cause air ionization and eventual termination failure.

• Stress-control tube:A black high-permittivity (High-K) tube helps absorb and redistribute distorted electric-field lines along the insulation, reducing the risk of partial discharge.
• Stress Relief Mastic:A compound applied carefully at the end of the copper screen to fill microscopic air gaps, reducing the possibility of air pockets ionizing under 20 kV stress.

2. Insulation and Protection System& Anti-tracking)

• Red Insulation Tubes:Long tubes covering the three phases, manufactured from polymeric materials resistant to electrical tracking—the carbonized surface paths that can form due to moisture and dust and may lead to short circuit.
• 3-Way Breakout:A heat-shrink component covering the area where the cable separates into three phases. It is internally lined with active hot-melt adhesive to provide a moisture seal that limits oxygen and water ingress into the aluminum cable core.

3. Earthing System& Screening)

• Flexible Copper Braids:Used to maintain continuity of the cable copper-screen earthing path and safely conduct fault currents to the station earth system.
• Constant Force Springs:Used to secure the earthing braids to the copper screen with consistent pressure that is less affected by vibration or thermal expansion.

Chapter Two: Technical Performance and Aluminum-Conductor Challenges

Elsewedy aluminum terminations include features designed around the characteristics of aluminum:

• Aluminum Oxidation Management:The kit includes conductive grease that helps prevent immediate formation of an insulating oxide layer after conductor cleaning, supporting current flow with low contact resistance.
• Compact Design:Because these are indoor terminations, tube lengths are optimized for confined spaces inside medium-voltage switchgear cells without compromising required creepage distances.
• Resistance to Thermal Aging:The polymer materials are designed to retain flexibility and compression on the cable over extended service periods, helping limit dust or moisture ingress as the installation ages.
• Impulse-Voltage Withstand:The terminations are designed and tested to withstand high-voltage surges associated with switching operations on the network.

Chapter Three: Indoor-Termination Applications in Critical Facilities

1. Main Switchgear:Final connection of aluminum cables arriving from transformer substations at 20 kV.
2. Electrical Transformers:Connecting medium-voltage cables to transformer incoming terminals, whether oil-filled or dry type, inside factory transformer rooms.
3. Renewable-Energy Plants:Indoor connections in wind and solar farms, where aluminum cables are widely used for their economic advantages.
4. Factories and Large Facilities:Supporting power continuity at sites that depend on extensive internal medium-voltage networks.

Chapter Four: Engineering Installation and Testing Guide for Aluminum

Termination failures are often associated with installation errors, so installers should follow the specified procedure carefully:

• Aluminum Conductor Treatment:The aluminum surface should be brushed immediately after stripping to remove oxide, then coated with conductive grease before fitting the lug.
• Microscopic Insulation Cleaning:Clean the XLPE insulation with isopropyl-alcohol wipes to remove carbon particles left by the semiconductive layer; residual contamination can create a path for electrical breakdown.
• Uniform Heating:Use a gas torch with a soft blue flame and shrink from bottom to top, from the breakout toward the lugs, to expel air and avoid trapping it inside the tubes.
• Pre-Energization Testing:Perform insulation-resistance and appropriate high-voltage withstand testing (Hi-Pot where applicable) to verify 100% installation integrity before energization.