Introduction: The Cable That Powers the E-RTG Revolution

The global container terminal industry is undergoing its most profound transformation in decades: the electrification of diesel RTG (Rubber-Tired Gantry) cranes into E-RTGs — machines that draw shore power through a reeling cable instead of burning diesel fuel, achieving up to 95% savings in fuel costs while eliminating local tailpipe emissions [VAHLE — eRTG Brochure]. At the heart of every E-RTG electrification system — whether from Cavotec, Conductix-Wampfler, igus, or VAHLE — is a single cable that must deliver both massive three-phase power AND high-bandwidth fiber optic data through a motorised reel that spools thousands of times per year. That cable is the (N)SHTOEU Trommelflex® KSM-S FO.

With 30 configurations spanning 8 power cross-sections from 3×25 to 3×240 mm² and three fiber optic types (E9/125 singlemode, G50/125 multimode, G62.5/125 multimode) at 12 or 24 fiber counts, the KSM-S FO covers every E-RTG, STS crane, ASC (Automated Stacking Crane), and ARMG (Automated Rail-Mounted Gantry) application in the global container handling industry. Cavotec confirms that their E-RTG solutions are based on cable reel technology with integrated fibre optics critical to terminal operations [Cavotec — E-RTG Solutions]. Prysmian markets the identical cable construction under their TROMMELFLEX KSM-S brand [Prysmian — LV Reeling for E-RTG].

Technical Anatomy: Full Specification

30 Configurations: Complete Matrix with Fiber Type Variants

Seven Critical Upgrades Over Standard TROMMELFLEX (K)

The KSM-S FO is not simply a TROMMELFLEX (K) with fiber optics added — it is an extensively upgraded cable with seven performance improvements that justify its use in the demanding E-RTG and automated crane environments:

These upgrades reflect the E-RTG operating environment: faster gantry travel speeds (requiring 180 m/min vs. 120 m/min), longer cable runs on larger terminal yards (requiring higher tensile strength), colder port climates worldwide (requiring −40°C dynamic), and the premium 5GM5 neoprene that Cavotec, Conductix, and other reel manufacturers specify for their E-RTG cable management systems. The use of bare copper (instead of tinned) reflects that E-RTG cables operate within enclosed reel systems where salt-spray corrosion is less of a concern than in exposed vertical reel applications.

Fiber Optic Architecture: E9, G50, G62.5 — Choosing the Right Fiber

Feichun’s technical recommendation based on the FeiChun TRATOSMART FO engineering analysis: specify E9/125 singlemode for all new E-RTG and automated terminal installations — it provides the highest bandwidth headroom (virtually unlimited at crane distances), the lowest attenuation (0.35 dB/km at 1310 nm vs. 3.5 dB/km for multimode at 850 nm), and future-proofs the infrastructure for 10G+ Ethernet upgrades. Specify G50/125 for standard multimode infrastructure. Specify G62.5/125 only for like-for-like replacement of existing legacy installations [FeiChun — TRATOSMART FO: Fiber Selection Guide].

Split Earth + Interstitial Fiber Protection: The Crush-Shield Design

The KSM-S FO uses a construction that Feichun calls interstitial fiber isolation — the precise positioning of fragile optical fiber tubes within the structural valleys between the massive copper power cores, where the copper itself acts as a crush shield. The protective earth conductors are split in the outer interstices (as stated in the datasheet) — distributed symmetrically around the cable to create balanced mechanical geometry. This split-earth design, combined with the fiber optic tubes positioned in the protected inner interstices, creates a geometry where the copper conductors absorb 100% of the radial drum compression force before it reaches the glass fibers [FeiChun — Interstitial Fiber Isolation Architecture].

This crush protection is critical because the primary failure mode of composite reeling cables is not electrical but optical. The copper conductors and EPR insulation can survive millions of reel cycles, but the glass fibers (125 μm diameter) are exquisitely sensitive to the radial compression that occurs during multi-layer drum winding, where upper cable layers press down on lower layers with forces proportional to cable tension and drum diameter. Without the interstitial protection geometry, fiber attenuation increases progressively with every drum winding cycle until optical signal loss exceeds the link budget — silently degrading SCADA, video, and safety data communication before any visible cable damage occurs.

The Special Configuration: 3×120+1×70+(6×2.5)C+FO

Three unique configurations (Part Nos. 054561–054563) add a screened control bundle (6×2.5)C to the power + FO architecture. This “C” bundle provides 6 copper control cores at 2.5 mm² with integrated copper braid screening — delivering EMC-protected signal circuits for crane encoder feedback, safety interlock data, or precision sensor signals that must be isolated from VFD electromagnetic interference. Combined with the 3×120 mm² power cores, 1×70 mm² neutral/earth, fiber optics, and the screened control bundle, this configuration delivers power, screened control, and fiber optic data in a single cable — the ultimate “one cable does everything” solution for complex automated crane systems.

Application: E-RTG, STS, ASC, and Automated Terminal Systems

KSM-S FO vs. Standard TROMMELFLEX (K) vs. URSUS: Selection Guide

Choose KSM-S FO when: fiber optic communication is required alongside power (E-RTG, automated cranes, any application with SCADA/video/sensor data). Choose standard TROMMELFLEX (K) when: only copper power/control is needed, no fiber optics, and the application operates at ≤120 m/min under medium mechanical stress. Choose URSUS VS when: maximum mechanical strength is needed for vertical self-supporting applications with Kevlar® — but without fiber optics.

Cost-Effective Alternative from Feichun

Feichun Lead Times: 8–12 weeks. European (Klaus Faber/Prysmian): 20–34 weeks. (Note: Klaus Faber’s online shop shows delivery times of approximately 34 weeks for URSUS MT FO variants — composite FO cables are the longest-lead items in the catalogue.)

Technical FAQ

Why bare copper instead of tinned (unlike the standard TROMMELFLEX K)?

E-RTG cables operate within enclosed motorised reel systems (Cavotec APS, Conductix cable reel carriers, etc.) where the cable is protected from direct salt-spray exposure. Bare copper provides equivalent electrical performance at lower cost and slightly lower conductor resistance (7.98 Ω/km vs. 8.21 Ω/km for 2.5 mm²). For applications where the cable will be exposed to marine atmosphere outside the reel enclosure, Feichun can supply tinned copper variants on request.

Can the fiber type be mixed (e.g., 12 SM + 12 MM) within a single cable?

Yes. The datasheet notes that cables can be manufactured to order or project-specific with E9/125, 50/125, or 62.5/125 fibres or their various combinations. Feichun supports all standard and custom fiber combinations. Contact Feichun’s engineering team for mixed-fiber configurations.

What does “20 N/mm² at the conductor” mean for the Fzp values?

The Fzp (permanent tensile) = 20 × total copper cross-section. For 3×70+2×35/2 (total copper: 70×3 + 35 = 245 mm²): Fzp = 20 × 245 ≈ 4,900 N. The datasheet lists 4,200 N — slightly conservative. The 20 N/mm² limit represents the stress at which the bare copper conductors begin to yield. This is 33% higher than the 15 N/mm² limit of the standard TROMMELFLEX (K).

Is this cable compatible with Cavotec APS (Automatic Plug-in System)?

Yes. Cavotec confirms their E-RTG solutions are based on cable reel technology with integrated fibre optics [Cavotec — E-RTG]. The KSM-S FO is the standard cable type specified by Cavotec, Conductix-Wampfler, and other E-RTG system integrators. Feichun supplies KSM-S FO equivalents that are dimensionally and electrically compatible with all major E-RTG reel systems.