EoW November 2010

technical article

Aluminium conductors steel reinforced • (ACSR) using a single steel wire core All aluminium and aluminium alloy • conductors (AAC & AAAC) Cabling of insulated conductors • Ceeco Bartell believes its roll form strander is the only process to fully utilise the advantages of single input wire (SIW) diameter. SIW represents a strand and design mentality, with a manufacturing methodology that effectively reduces the conversion cost from rod to strand without compromising conductor performance. This concept replaces the traditional stranding of wires using different wire diameters with the stranding of wires using the same wire diameter for a wide range of cross sections. SIW diameter meets major conductor standards such as IEC 60228, HD 383 and the ASTM standards. By incorporating a single input wire diameter program into the strand design, significant savings can be achieved in wire drawing, stranding and the insulation processes. Traditionally a finished stranded conductor requires its own drawn wire diameter. Each wire diameter typically requires a new string-up in the wire drawing machine. Some conductor designs require more than one drawn wire size. The set up time taken on the drawing, combined with inventory levels that are necessary to manage the number of wire diameters, represent unnecessary activities that add to the cost of conversion from rod to strand. The SIW approach, using the same input wire diameter to finish a range of stranded conductors, eliminates much of the unnecessary activity associated with the traditional set up.

Figure 1 ▲ ▲ : Close up of roll formers

Figure 2 ▲ ▲ : Roll form unit and closing point

Single input wire schedules

Compact

Six wire sizes required using a conventional system One wire size required using SIW system

Figure 3 ▲ ▲

It further allows more precise distribution of wire tension in each layer, optimising the straightness of the resulting conductor. The shaped conductors are formed into a compact unilay strand using a high-speed double twist strander. The machine is a side-loading unit equipped with a standard floor loader, designed to load and unload

the take-up reel with minimum operator effort. The scope of products that can be manufactured includes: Copper and aluminium stranded • conductors between 8AWG and 600kcmil or 10mm 2 and 300mm 2 Bunched conductors to compact • strand with fill factors between 76% and 97%

Figure 4 ▼ ▼ : Process cost/twist comparison

$ Planetary Strander Planetary Strander

$ Rigid Strander Rigid Strander

Capital cost/ Twist

$ Drum Twister

$ Tubular Strander

$ Double twist Strander Double Twist Strander

Tubular Strander

Drum Twister

Factors

Capital cost/twist

1

3-5

7-16

9-12

16-24

“Working factor”

Significant (rigid) Unilay only

Almost none (planetary) Not applicable

Significant (rigid)

Significant (rigid)

Almost none (planetary)

Lay limitations Layer limitations Typical payoff package

None None

None None

None None

Up to 4 layers

2 layers

Stem

Bobbin

Stem

Bobbin

Bobbin

Required loading cycle

Required loading cycle

Required loading cycle

Continuous

Payoff mode

Continuous

69

EuroWire – November 2010