Production Process of 26/35kV cu/xlpe/cwa/sta/pvc 1×630 Power Cable
Created on 2025.12.04
Production Process of 26/35kV cu/xlpe/cwa/sta/pvc 1×630 Power Cable
The production of a high-voltage XLPE-insulated power cable like cu/xlpe/cwa/sta is a sophisticated, multi-stage process that demands precise control to ensure exceptional electrical performance, mechanical strength, and long-term reliability. Below is a detailed breakdown of the key production stages.
1. Conductor Manufacturing
· Material: High-purity, oxygen-free electrolytic copper is used.
· Process: Multiple copper wires are stranded together in concentric layers around a central wire using a rigid stranding machine. For a 630mm² conductor, this process ensures flexibility, a compact circular shape, and excellent conductivity.
· Quality Control: The conductor diameter, DC resistance, and stranding lay length are continuously monitored to meet strict standards.
2. Conductor Screening
· Purpose: To smooth the conductor surface, eliminate sharp protrusions, and control the electric field at the conductor-insulation interface.
· Process: A semi-conductive (semicon) cross-linked polyethylene tape is applied helically over the stranded conductor, or an extruded semicon layer is added.
3. Triple Extrusion - Inner Semicon, XLPE Insulation, Outer Semicon
This is the core and most critical stage for HV cable performance.
· Process: The conductor passes through a state-of-the-art CCV (Catenary Continuous Vulcanization) line. Three layers are co-extruded simultaneously in a single, uninterrupted operation:
a. Inner Semicon Layer: Creates a smooth, equipotential surface.
b. XLPE (Cross-Linked Polyethylene) Insulation Layer: Provides the primary dielectric strength. The XLPE is cross-linked (cured) under high temperature and pressure in the vulcanization tube to form a thermoset material with superior thermal and electrical stability.
c. Outer Semicon Layer: Forms another smooth, conductive boundary.
· Criticality: This triple extrusion ensures perfect bonding between layers, eliminates impurities or voids, and is vital for achieving uniform electrical stress distribution. The insulation thickness is precisely controlled to match the 26/35kV rating.
4. Insulation Screening & Diagnostic Testing
· Process: After cooling, the insulated core undergoes a partial discharge (PD) test and a high-voltage (HV) withstand test (e.g., at ~65kV AC for this rating) in a shielded room. This is a 100% online test to detect any microscopic defects.
· Purpose: To guarantee the integrity and purity of the insulation system before further manufacturing.
5. Metallic Screen
· Purpose:
Equalizes electrical field distribution around the insulation.
Provides a path for fault currents and capacitive charging currents.
Shields against electromagnetic interference (EMI).
· Process: Multiple copper wires are helically applied in two opposing layers over the core using a high-precision screening machine.
6. Bedding with Conductive Tape
A copper or aluminum conductive tape (often overlapping) is helically applied over the wire screen to hold the wires firmly in place and improve screen contact.
7. Inner Sheath (Bedding) Extrusion
A layer of extruded PVC or PE compound is applied over the screened core. This bedding layer provides a smooth, round base for the armor, and offers additional moisture protection.
8. Armoring
· Purpose: The armoring, which offers robust mechanical protection (especially against crush forces) and some rodent resistance.
· Process: Two aluminum tapes are applied helically in opposite directions over the bedding layer with a small gap, forming a locked armor.
9. Outer Sheath (Jacket) Extrusion
· Material: Polyvinyl Chloride (PVC) is extruded over the armor. The PVC compound is selected for durability, resistance to abrasion, chemicals, sunlight, and flame retardancy.
· Process: The sheath is applied via an extruder, then cooled in water troughs. Printing of cable markings (specification, voltage rating, manufacturer, meter marks) is done online.
9. Final Testing & Coiling
· Tests: The finished cable undergoes a final suite of tests, which may include another HV test, sheath spark test, conductor resistance check, and dimensional verification.
· Packaging: The cable is coiled onto large wooden reels or steel spools, ready for shipment.
Summary
The production of 26/35kV cu/xlpe/cwa/sta/pvc 1×630 Power Cable is a capital - intensive, technology - driven process where quality is built into each sequential stage. The combination of high - voltage XLPE insulation via CCV, a hermetic corrugated metallic sheath, and steel tape armor results in a cable designed for demanding fixed installations in networks, tunnels, or direct burial where moisture protection and high mechanical strength are required.
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