What Is Reeling Cable? 

Part 1: Construction & Performance

 A Reeling Cable is a flexible cable specifically designed for applications where the cable is repeatedly wound onto and unwound from a cable reel during equipment operation.

Unlike cables used in fixed installations, reeling cables must withstand continuous mechanical movement. Depending on the application, the cable may be exposed to repeated bending, torsion, tensile forces, compression, abrasion, and harsh environmental conditions. Reeling cables are commonly used in port cranes, mining equipment, industrial automation systems, material handling equipment, and other mobile machinery.

The performance of a reeling cable depends not only on its electrical design, but also on its conductor construction, internal mechanical structure, outer sheath, bending radius, reel geometry, traveling speed, tensile load, and operating environment.

This guide explains the construction, key performance parameters, applications, selection criteria, installation requirements, and common failure modes of reeling cables.

 A Typical Reeling Cable Produced by RouLine

1. What Is a Reeling Cable?

A reeling cable is a dynamic cable designed to operate on a cable reel through repeated winding and unwinding cycles.

A typical operating sequence can be described as:

Winding → Traveling → Unwinding → Rewinding

 During this process, the cable must maintain its electrical and mechanical integrity while being repeatedly deformed.

2. Reeling Cable Construction

The structure of a reeling cable follows a functional gradient principle.

From the conductor to the outer sheath, each layer performs a different electrical or mechanical function.

Conductor

The conductor uses high purity oxygen free copper with a purity of no less than 99.95%, and tin plating is applied when necessary to resist sulfide corrosion.

To achieve a long flex life, the conductor construction must use a Class 6 extra fine stranded copper structure, with individual wire diameters typically controlled within the range of 0.15 mm to 0.30 mm. The stranding lay ratio, defined as the ratio of lay length to stranded outer diameter, is strictly controlled within 8 to 12 times so as to balance bending flexibility and resistance to tensile creep. The DC resistance of the conductor and the maximum allowable working temperature must comply with IEC 60228 and GB/T 3956 standards.

Insulation

The insulation material is selected from ethylene propylene rubber (EPR), thermoplastic elastomer (TPE), or specially formulated temperature resistant PVC.

Selection basis:

↗EPR

Suitable for medium voltage environments (3.6/6 kV and above), with high dielectric strength (no less than 20 kV/mm), volume resistivity greater than 10¹⁵ Ω·cm, and excellent heat aging resistance (permissible long term working temperature of 90°C).

↗TPE/PVC

Used for low voltage (0.6/1 kV) control circuits, balancing processing performance and cost control.

The minimum thickness at the thinnest point and the eccentricity of the insulation layer must meet the additional insulation safety margin requirements for mobile cables specified in GB/T 5013 and VDE 0250.

Filling and Inner Sheath

Materials such as polyester fibres or aramid yarns may be incorporated into specialised designs where additional mechanical support is required. These components can provide several functions.

↗Mechanical Load Transfer

A properly designed strength structure can help transfer mechanical loads away from the copper conductors. This reduces the risk of excessive longitudinal stress being directly transmitted to the conductive elements.

↗Geometrical Stability

The inner sheath can help maintain the relative position of the individual cores and preserve the overall circular geometry of the cable. This becomes increasingly important as the number of cores and cable diameter increase.

Shielding

Shielding is an optional structural element and is normally specified when electromagnetic compatibility or signal integrity is important. A commonly used construction is a tinned copper wire braid.

Outer Sheath

The outer sheath is the primary mechanical and environmental protection layer of a reeling cable. It must withstand the actual operating environment while remaining flexible enough for repeated movement.

3. Key Performance Parameters of Reeling Cable

Minimum Dynamic Bending Radius

The minimum dynamic bending radius is the smallest radius that the cable is designed to tolerate during dynamic operation. It is normally expressed as a multiple of the cable's outside diameter:

R ≥ k × D

R = minimum bending radius

D = cable outside diameter

k = coefficient determined by the cable construction and application

The actual value should be taken from the cable manufacturer's specification.

Engineering impact

if the bending radius falls below this threshold, the conductor and shielding layer will enter the plastic deformation zone, and the accumulated bending strain will exceed the fatigue limit of the material (the strain fatigue threshold for copper is approximately 0.2% to 0.3%), resulting in internal conductor breakage or shielding breakdown. This factor accounts for more than 60% of early failure cases in reeling cables according to statistics.

Allowable Tensile Load

Definition: the static or dynamic tensile force that the cable can withstand longitudinally over the long term, expressed in N (newtons) or kN (kilonewtons).

Specification requirements: for reeling systems with a vertical suspension travel exceeding 80 m, an aramid yarn braided tensile load bearing element or an independent steel wire supporting element must be added within the cable construction. The allowable working tensile force shall satisfy:

F_allow = F_self + F_acc + F_extra

where F_self is the self weight of the cable, F_acc is the inertial force due to acceleration and deceleration of the equipment, and F_extra is the drag resistance.

Engineering impact: tensile loading beyond the limit will cause necking once the conductor elongation exceeds 0.5%, leading to increased resistivity and worsened local heating. At the same time, the adhesion between the insulation and the sheath is destroyed, causing the phenomena of core pull out or bulging.

Traveling Speed and Reeling Frequency

A cable moving several times per hour experiences a very different duty cycle from one operating continuously throughout a production shift. Important parameters include:

Traveling speed

Acceleration

Deceleration

Reeling cycles per hour

Total operating hours

Expected service life

A reeling cable is not simply a flexible power cable. It is a specialised dynamic cable system designed to withstand repeated winding, unwinding, bending, mechanical loading, and environmental exposure.

For applications such as port crane cables, mining machinery, industrial automation, and mobile equipment, the correct cable construction must be selected according to the actual operating conditions.

Continue to Part 2: Where Is Reeling Cable Used and How Do You Choose the Right One?

4. Frequently Asked Questions

What is a reeling cable?

A reeling cable is a flexible dynamic cable designed for repeated winding and unwinding on a cable reel.

What are reeling cables used for?

Reeling cables are commonly used in cranes, ports, mining equipment, industrial automation, material handling systems, and mobile machinery.

Can a regular flexible cable be used on a cable reel?

Not necessarily. The cable must be specifically suitable for the mechanical movement, bending radius, reel geometry, and operating conditions of the application.

What is the difference between reeling cable and flexible cable?

Flexibility alone does not make a cable suitable for reeling. Reeling cables are designed for repeated dynamic movement and mechanical stresses associated with cable reels.

What is the minimum bending radius of a reeling cable?

It depends on the cable construction and application. The manufacturer's specified dynamic bending radius should be matched to the actual reel diameter and cable routing system.