Introduction: Understanding Cable Crushing Phenomenon 引言：理解电缆挤压现象

Cable crushing represents one of the most insidious and costly failure modes in reeling cable systems for container handling cranes, mobile equipment, and industrial material handling applications. When we speak of cable crushing in the context of drum winding systems, we are describing a progressive mechanical failure that occurs when cables wound onto a drum at high tension are later compressed by additional cable layers wound at even higher tension. This creates a compound crushing effect where the inner layers experience compressive forces far exceeding what the cable construction was designed to withstand. Understanding how to prevent this failure mode through proper tension management is essential for ensuring reliable, long-term operation of (N)TSKCGEWÖU cables in demanding crane applications. 电缆挤压代表了集装箱处理起重机、移动设备和工业物料搬运应用中卷筒电缆系统最隐蔽且代价最高的故障模式之一。

The (N)TSKCGEWÖU cable designation, standardized under German DIN VDE 0276 Part 620 and international IEC 60502-2, represents a specialized category of medium-voltage reeling cables engineered specifically for applications involving extreme mechanical stresses. The nomenclature itself provides important insight into the cable construction. The “N” prefix denotes an energy cable with copper conductors, “TSK” indicates a tinned copper braided screen design, “C” represents cross-linked polyethylene (XLPE) insulation, “GE” signifies an inner sheath, “W” denotes the outer sheath material, “Ö” indicates oil resistance, and “U” specifies the cable is designed for voltages up to 6kV or higher depending on the specific variant. These cables are predominantly deployed in ship-to-shore cranes, rubber-tired gantry cranes, automated stacking cranes, and other high-performance material handling systems where cable reliability directly impacts operational productivity and safety. (N)TSKCGEWÖU电缆名称根据德国DIN VDE 0276第620部分和国际IEC 60502-2标准化，代表了一类专门设计用于涉及极端机械应力应用的中压卷筒电缆。

Sources: Eland Cables – German MV Cable Nomenclature and Standards, Prysmian Group – PROTOLON (N)TSKCGEWÖU Technical Datasheet

The Mechanics of Cable Crushing: Why Tension Management Matters 电缆挤压机制：为什么张力管理很重要

To truly understand why tension management is so critical in monospiral drum systems, we need to explore the fundamental mechanics of how forces are transmitted through wound cable layers. When you wind a cable onto a drum under tension, that cable exerts both radial compression on the drum core and tangential forces that resist the winding motion. However, the more significant issue arises when subsequent layers are wound over existing layers. Each new layer of cable, wound at its own particular tension, exerts an inward radial force on all the layers beneath it. This force is not uniformly distributed but instead concentrates at the contact points where the outer cable layer rests in the valleys between cables in the layer below. 要真正理解为什么张力管理在单螺旋卷筒系统中如此关键，我们需要探索力如何通过缠绕的电缆层传递的基本机制。

The crushing mechanism becomes particularly severe when an installation uses what is called a “flat” or uniform tension profile, where the same high tension is applied throughout the entire winding process. Consider what happens in this scenario when you have wound perhaps ten or fifteen layers of cable onto the drum, with each layer at 1500 pounds of tension. The innermost layers are now experiencing not just the 1500 pounds they were wound at, but also the cumulative radial compressive force from all the layers above them. Field experience documented in wireline operations shows that this can result in the armor wires of the innermost layers being pressed into the plastic insulation with sufficient force to cut through and cause electrical shorts to the conductor. In severe cases, the compressive force can actually deform the drum core itself, which then causes the drum flanges to spread outward under the accumulated pressure. 当安装使用所谓的”平坦”或均匀张力分布时，挤压机制变得特别严重。

Source: Camesa Wireline – Technical Bulletin 009: Drum Crush Failures

Radial Compression Forces on Drum Core 卷筒芯上的径向压缩力

The radial pressure that cable under tension exerts on a drum surface can be calculated using the classical drum hoop stress formula. This fundamental relationship, documented in engineering references including the ASM Metals Handbook for Failure Analysis and Prevention, expresses the pressure as a function of the line tension, drum diameter, and cable diameter. The formula takes the form of P = 2T / (D × d), where P represents the total rope or cable pressure on the drum exterior measured in pounds per inch of drum width, T is the line tension in pounds, D is the root diameter of the drum in inches, and d is the cable diameter in inches. This seemingly simple equation reveals a critical insight: for a given cable size and drum diameter, the pressure on the drum increases directly with line tension. Double the tension and you double the crushing pressure on everything beneath. 张力电缆在卷筒表面上施加的径向压力可以使用经典的卷筒环应力公式计算。

However, this basic formula only tells us about the pressure at a single layer interface. The actual situation in a multi-layer winding is far more complex because each layer adds its contribution to the total compressive force experienced by the inner layers. Research into cable drum mechanics shows that the cumulative effect follows a compound pattern where inner layers experience pressures that can be several times higher than what a simple linear accumulation would suggest. This compound crushing effect is the reason why drum failures and cable crushing failures typically occur at inner layers rather than at the outer surface where you might initially expect them. 然而，这个基本公式只告诉我们单层界面的压力。多层缠绕中的实际情况要复杂得多。

Source: Practical Machinist Forum – Engineering Discussion on Drum Hoop Stress Calculations

Monospiral Drum Characteristics and Operating Principles 单螺旋卷筒特性和操作原理

Before we can develop proper tension formulations, we must understand what distinguishes a monospiral drum from other cable storage configurations and why this design is preferred for crane applications despite its complexity. A monospiral drum features a single helical groove machined or formed into the drum surface, with the groove pitch precisely matching the cable diameter. As the drum rotates, the cable follows this spiral path, ensuring that each wrap of cable sits in its designated groove and naturally advances laterally across the drum face. This design contrasts with cylindrical drums where cable can wind in multiple layers without guided positioning, and with duospiral or multispiral designs where multiple independent helical paths allow faster winding but create additional complexity in tension management. 在我们制定适当的张力公式之前，我们必须了解单螺旋卷筒与其他电缆存储配置的区别。

The monospiral design offers several significant advantages for crane cable systems. Most importantly, it provides highly predictable cable positioning where each wrap occupies a known location on the drum, eliminating the unpredictable stacking patterns that can occur with unguided winding. This predictability allows for more accurate calculation of the effective drum radius at any point in the cable deployment cycle, which is essential for precise crane motion control and load positioning. The guided winding also distributes axial forces more evenly across the drum structure, reducing the likelihood of flange spreading or warping that can occur when cable bunches unevenly. Additionally, monospiral winding facilitates uniform application of variable tension profiles across the cable length, which as we will see is fundamental to preventing crushing failures. 单螺旋设计为起重机电缆系统提供了几个重要优势。

However, the monospiral configuration also introduces unique challenges that must be addressed through careful engineering. The primary challenge lies in managing the continuous change in effective drum diameter as cable is wound or unwound. When the cable rests in the first groove at the bottom of the spiral, the effective radius is at its minimum. As successive wraps fill the spiral path, each new layer effectively increases the drum radius by one cable diameter. This changing radius directly affects the mechanical advantage of the drum system, altering the relationship between drum motor torque and cable tension. For proper tension control, the drum drive system must compensate for this radius variation, either through mechanical gearing changes or more commonly through variable frequency drive control that adjusts motor torque based on the current cable layer position. 然而，单螺旋配置也引入了必须通过仔细工程设计来解决的独特挑战。

Sources: ResearchGate – The Monospiral Motorised Cable Reel in Crane Applications, Transprotec GmbH – Cable Drum Design and Winding Technology

Fundamental Tension Calculations for Drum Winding 卷筒缠绕的基本张力计算

Determining Required Cable Tension Range 确定所需的电缆张力范围

The starting point for any tension formulation is establishing the minimum and maximum tension values that the cable installation requires. The minimum tension must be sufficient to maintain cable control during unwinding operations and to prevent slack cable that could lead to tangling or incorrect layer formation. For most crane applications with (N)TSKCGEWÖU cables, practical experience shows that a minimum tension of approximately 50 to 100 pounds per square inch of cable cross-sectional area provides adequate control while minimizing unnecessary stress on inner layers. This translates to roughly 3 to 7 percent of the cable’s rated breaking strength, depending on conductor size and construction specifics. 任何张力公式的起点是建立电缆安装所需的最小和最大张力值。

The maximum permissible tension is constrained by several factors. First and most obvious is the cable’s own mechanical strength. Manufacturers typically specify maximum installation tension as 33 percent of the cable breaking strength for temporary installation conditions, with lower values recommended for permanent installations or where the cable will experience repeated tension cycling. For medium voltage cables like (N)TSKCGEWÖU variants, conductor pull-out from the termination assemblies becomes a concern at high tensions, so terminal design may further limit maximum allowable tension. Additionally, the mechanical capacity of the drum structure itself places an upper bound on permissible tension, particularly for the outer layers where maximum radius amplifies the torque applied to the drum shaft and bearings. 最大允许张力受几个因素限制。

Source: Superior Essex – Calculating Cable Pulling Tensions Guide

Establishing the Tension Profile Strategy 建立张力分布策略

With minimum and maximum tension limits established, the next step is developing a tension profile that varies appropriately across the cable length to prevent inner layer crushing while maintaining adequate control throughout the winding cycle. The fundamental principle, validated through decades of field experience in wireline operations and adapted for crane cable systems, follows a staged profile with distinct zones. The first zone establishes what is often called the bed layer or foundation layer using relatively low tension to create a smooth, uniform base. Typical bed layer tension ranges from 10 to 15 percent of cable breaking strength. This low initial tension minimizes the crushing force on the drum core while providing adequate tightness to prevent the first layer from shifting or becoming loose. 在确立了最小和最大张力限制后，下一步是制定一个张力分布，在电缆长度上适当变化。

Following bed layer establishment, tension is progressively increased over the next three to four layers, eventually reaching a working tension of approximately 25 to 33 percent of cable breaking strength. This graduated increase allows each successive layer to compress the layers beneath it, but because the inner layers were wound at lower tension, they can accommodate this compression without experiencing crushing damage. The working tension is then maintained for the middle portion of the cable length, typically encompassing about 40 to 50 percent of the total cable. This middle section represents the depth range where the crane will operate most frequently in typical port or material handling applications. 床层建立后，在接下来的三到四层中逐渐增加张力。

For the outer layers representing the final 30 to 40 percent of cable length, tension is progressively reduced with each successive layer. This reduction serves multiple purposes. It prevents the outer layers from applying excessive crushing force to the accumulated inner layers. It also accounts for the increasing effective drum radius, which amplifies the torque that a given cable tension applies to the drum shaft. Perhaps most importantly, the reduced outer layer tension helps maintain proper cable spooling when operating at shallow depths where the cable experiences minimal natural tension from its own suspended weight. Without this tension reduction in outer layers, cranes operating in shallow conditions can experience cable overrun, where slack cable feeds back onto the drum at lower tension than the existing outer layers, setting up conditions for subsequent crushing failures when the cable is next deployed to deeper operations. 对于代表最后30%到40%电缆长度的外层，随着每个连续层逐渐降低张力。

Source: Camesa Wireline – Drum Crush Technical Bulletin: Tension Profile Guidelines

Recommended Tension Formulation for (N)TSKCGEWÖU Cables (N)TSKCGEWÖU电缆的推荐张力公式

Based on engineering principles established for high-stress reeling applications and adapted specifically for medium-voltage crane cables, the following tension formulation provides a practical framework for preventing cable crushing while maintaining adequate winding control for (N)TSKCGEWÖU installations on monospiral drums. This formulation considers the unique characteristics of the TSKCGEWÖU construction, including its braided screen that provides some resistance to radial compression but remains vulnerable to crushing under high accumulated loads. 基于为高应力卷筒应用建立的工程原理，并专门适应于中压起重机电缆，以下张力公式为防止电缆挤压提供了实用框架。

Zone 1: Bed Layer (First 3-5 Wraps) 区域1：床层（前3-5圈）

Zone 2: Tension Build-up (Next 3-4 Layers) 区域2：张力建立（接下来的3-4层）

Zone 3: Working Tension (Middle 40-50% of Cable Length) 区域3：工作张力（电缆长度的中间40-50%）

Zone 4: Tension Reduction (Outer 30-35% of Cable Length) 区域4：张力减小（电缆长度的外部30-35%）

Calculating Layer-Specific Tensions 计算特定层的张力

To implement the tension profile strategy in practice, you need a systematic method for calculating the appropriate tension for each layer as the cable is wound onto the drum. The calculation begins by determining how many complete wraps of cable will fit on your particular drum geometry, then dividing these wraps into the tension zones we have defined. For a monospiral drum, the number of wraps equals the drum traverse width divided by the cable outer diameter, multiplied by the number of complete layers that fit between the drum core and the drum flanges. 要在实践中实施张力分布策略，您需要一种系统的方法来计算每层的适当张力。

Once you know the total wrap count, assign specific wrap ranges to each tension zone. For example, if your drum accommodates 500 total wraps of cable, you might assign wraps 1-15 to the bed layer zone (3 complete passes across the drum at 5 wraps per pass), wraps 16-80 to the tension build-up zone, wraps 81-325 to the working tension zone, and wraps 326-500 to the tension reduction zone. The exact distribution depends on your specific cable length, operating depth profile, and drum dimensions, but the proportions should generally follow the 3-5%, 7-10%, 40-50%, and 30-35% guidelines discussed earlier. 一旦您知道了总缠绕数，将特定的缠绕范围分配给每个张力区域。

Implementing Variable Tension Control 实施可变张力控制

Modern crane cable reel systems implement variable tension control through torque management of the drum drive motor. The fundamental relationship is that cable tension equals the motor torque divided by the effective drum radius at the current wrap layer. For a monospiral drum, the effective radius increases by one cable diameter for each complete layer wound onto the drum. To maintain constant cable tension as the radius increases, the motor torque must be increased proportionally. Conversely, to implement our desired tension profile where tension should vary with layer position, we must program the motor controller to apply a torque that accounts for both the current drum radius and the target tension for that particular layer. 现代起重机电缆卷筒系统通过卷筒驱动电机的扭矩管理实施可变张力控制。

Most crane installations use programmable frequency inverters or variable frequency drives that allow the operator or control system to specify motor torque as a function of cable position. During the initial cable spooling operation, the system records the drum rotation count and uses this to track which layer is currently being wound. The controller then references a preprogrammed torque curve that specifies the required motor torque for each layer to achieve the desired tension profile. More sophisticated systems may incorporate direct tension measurement using load cells positioned on the cable path between the crane boom and the drum, allowing closed-loop tension control that automatically adjusts motor torque to maintain the target tension regardless of varying conditions. 大多数起重机安装使用可编程变频逆变器或变频驱动器。

Source: ResearchGate – Monospiral Cable Reel Torque and Speed Calculations

Verification and Testing Procedures 验证和测试程序

Initial Commissioning Inspection 初始调试检查

After implementing a calculated tension profile on a new cable installation, systematic inspection and testing procedures help verify that the tension formulation is appropriate for the specific application conditions. The initial commissioning should include careful observation of the cable spooling pattern as layers are wound onto the drum. Proper tension produces tight, uniform wraps where each turn of cable sits closely against its neighbors without gaps or overlap. If gaps appear between wraps, the tension is insufficient. If the cable appears compressed or distorted as it enters the drum, with visible flattening of the circular cross-section, the tension is excessive. 在新电缆安装上实施计算的张力分布后，系统的检查和测试程序有助于验证张力公式是否适合特定的应用条件。

Pay particular attention to layer transitions, which represent the most challenging points in the winding cycle. As the cable completes one layer and transitions to the next, it must climb up over the previous layer to begin wrapping at the new radius. Proper tension ensures this transition occurs smoothly without the cable slipping back into a gap in the previous layer. Excessive tension at layer transitions can cause the cable to cut into the previous layer or damage the outer sheath through abrasion. Document the appearance of each layer transition with photographs, as these records become valuable reference points for troubleshooting any future issues or adjusting the tension profile for subsequent cable replacements. 特别注意层过渡，这代表了缠绕周期中最具挑战性的点。

Operational Monitoring 操作监控

During the first several months of crane operation with newly installed cable, implement a program of periodic visual inspection and performance monitoring to detect early signs of tension-related problems before they progress to cable failure. Inspect the drum during normal operational shutdowns, looking for any evidence of cable damage, particularly at the innermost visible layers. Signs of excessive crushing include visible indentation of the cable surface, splitting or cracking of the outer sheath, or visible displacement of the cable screen that shows through damaged sheath material. These indicators warrant immediate attention and may require adjustment of the tension profile for future cable installations. 在使用新安装电缆的起重机运行的前几个月期间，实施定期视觉检查和性能监控计划。

Electrical performance monitoring provides another avenue for detecting crushing damage before it causes complete cable failure. Periodic insulation resistance testing of the cable conductors can reveal deteriorating insulation that may result from crushing-induced stress or from armor wire penetration. Partial discharge testing, while requiring specialized equipment, can detect incipient insulation breakdown even before insulation resistance values show significant change. Many modern ship-to-shore cranes incorporate continuous monitoring systems that track cable electrical parameters and alert operators to degradation trends that may indicate crushing or other mechanical damage. 电气性能监控提供了另一种途径来检测挤压损伤。

Source: Polywater Corporation – Sidewall Pressure and Cable Damage Prevention

Common Mistakes and How to Avoid Them 常见错误及避免方法

Mistake 1: Using Constant High Tension Throughout Winding 错误1：在整个缠绕过程中使用恒定的高张力

Perhaps the most common tension-related mistake is applying a single “safe” tension value throughout the entire cable length, typically set conservatively high to ensure tight winding and prevent slack cable during shallow operations. While this approach seems logical from a cable control perspective, it fails to account for the cumulative crushing effects we have discussed. The solution is implementing the graduated tension profile with lower tension for inner layers and higher tension in the middle working zone, even though this requires more complex control systems and careful commissioning. The investment in proper variable tension control pays dividends in dramatically extended cable service life and elimination of premature crushing failures. 也许最常见的与张力相关的错误是在整个电缆长度上应用单一的”安全”张力值。

Mistake 2: Neglecting Cable Overrun Events 错误2：忽视电缆过冲事件

Cable overrun occurs when a crane approaches its minimum working depth very slowly or when a restriction in the cable path temporarily stops cable payout while the drum continues to rotate. These events result in several wraps of cable returning to the drum at very low tension, often essentially slack. If these low-tension wraps are subsequently compressed by high-tension cable wound over them during the next deep operation, severe crushing damage is virtually guaranteed. The solution requires operator training to recognize overrun conditions and procedures for immediate corrective action, which typically involves running the crane to maximum depth as soon as possible after an overrun event to restore proper tension throughout the cable length before significant additional cable is wound over the affected area. 当起重机非常缓慢地接近其最小工作深度时，或者当电缆路径中的限制暂时停止电缆释放而卷筒继续旋转时，会发生电缆过冲。

Mistake 3: Inadequate Drum Core Strength 错误3：卷筒芯强度不足

Even with perfect tension management, inadequate drum core design can result in crushing failures through a different mechanism. If the drum core does not possess sufficient hoop strength to resist the radial compression from wound cable, the core itself will compress slightly, which then allows the cable wraps to tighten further, creating a feedback loop that can progress to catastrophic drum failure. Proper drum design requires calculating the hoop stress in the drum shell using the pressure formulas we discussed earlier and ensuring the drum wall thickness and material properties provide adequate safety margin. Many crane drum failures attributed to “cable crushing” are actually drum crushing failures caused by inadequate drum structure for the applied cable tensions. 即使采用完美的张力管理，如果卷筒芯设计不充分，也可能通过不同的机制导致挤压故障。

Source: Practical Machinist Engineering Forum – Drum Hoop Stress Analysis

Application Examples for Different Crane Types 不同起重机类型的应用示例

Ship-to-Shore (STS) Container Cranes 岸到船（STS）集装箱起重机

Ship-to-shore cranes represent perhaps the most demanding application for (N)TSKCGEWÖU cables, with cable lengths often exceeding 100 meters, operating depths varying from 5 to 50 meters, and duty cycles involving thousands of container lifts per day. For STS applications, the tension formulation should emphasize a conservative working tension in the 25-28% of breaking strength range to account for the continuous cycling and rapid acceleration forces that these cranes experience. The tension reduction zone should be extended to encompass the outer 40% of cable length to provide adequate control during frequent shallow-depth operations when servicing containers on upper deck tiers. Many STS installations benefit from incorporating load cell-based tension monitoring that allows the control system to automatically adjust winding tension based on measured cable loads during each lift cycle. 岸到船起重机可能代表了(N)TSKCGEWÖU电缆最苛刻的应用。

Rubber-Tired Gantry (RTG) Cranes 橡胶轮式龙门起重机（RTG）

RTG cranes typically operate with shorter cable lengths (30-50 meters) and more consistent working depths compared to STS cranes, allowing for a more uniform tension profile through the working zone. However, RTG cranes often operate in more confined spaces where cable damage from contact with structural elements poses an additional risk. For RTG applications, slightly higher working tensions in the 30-32% range help maintain positive cable control and reduce the likelihood of cable sag that could result in contact damage. The key consideration for RTG installations is ensuring the outer layer tension reduction is properly coordinated with the minimum operating height to prevent overrun conditions when working at minimum extension. RTG起重机通常使用较短的电缆长度（30-50米），与STS起重机相比，工作深度更加一致。

Standards and Regulatory Considerations 标准和法规考虑

While no single standard specifically addresses tension formulation for cable crushing prevention in crane applications, several relevant standards provide framework requirements that inform proper practice. DIN VDE 0298-4 establishes current carrying capacity and installation requirements for power cables including reeling applications, though it does not specify detailed tension limits. The FEM 9.511 standard published by the European Federation of Materials Handling addresses crane cable specifications and includes recommendations for drum design but focuses primarily on electrical characteristics rather than mechanical installation parameters. 虽然没有单一标准专门解决起重机应用中防止电缆挤压的张力公式，但几个相关标准提供了框架要求。

For mining and heavy industrial applications, standards such as AS 1418.1 (Australian standard for crane design) provide detailed guidance on drum shell design including formulas for hoop stress calculations that help ensure drum structures can withstand planned cable tensions without failure. The most comprehensive guidance on tension management comes from industry-specific technical bulletins published by cable manufacturers and crane equipment suppliers, which often draw on extensive field experience to provide practical recommendations adapted to specific equipment configurations and operating conditions. Consulting these manufacturer resources during system design and installation planning provides the most reliable path to developing appropriate tension formulations for your particular application. 对于采矿和重工业应用，AS 1418.1等标准（澳大利亚起重机设计标准）提供了关于卷筒壳体设计的详细指导。

Sources: Prysmian Group – PROTOLON Cable Installation Guidelines, Practical Machinist Forum – AS 1418.1 Drum Design Standards