Technical Analysis: Why do some VDE cables have a “Z” in their code (e.g., (N)TSZCGEWÖU)?
Anhui Feichun Special Cable Co., Ltd. – Engineering Report
Specialists in High-Tensile Reeling and Vertical Lift Cables
1. Executive Summary: The Meaning of “Z”
In the German VDE cable designation system (DIN VDE 0250), the letter “Z” stands for the German word “Zugentlastung”, which translates to “Strain Relief” or “Tensile Reinforcement.” When you see “Z” in a code like (N)TSZCGEWÖU, it signifies that the cable is equipped with a dedicated central supporting element (often Aramid or Steel) designed to bear mechanical load, relieving stress from the copper conductors.
在德国VDE电缆型号系统（DIN VDE 0250）中，字母 “Z” 代表德语单词 “Zugentlastung”，意为“应变消除”或“抗拉增强”。当您在如 (N)TSZCGEWÖU 的代码中看到“Z”时，它表示该电缆配备了专用的中央支撑元件（通常是芳纶或钢丝），旨在承受机械负载，从而减轻铜导体的应力。
2. Detailed Breakdown of (N)TSZCGEWÖU
To fully understand the role of the “Z”, we must analyze it within the context of the full designation.
为了充分理解“Z”的作用，我们必须在完整的型号背景下对其进行分析。
| Symbol (符号) | German Term (德语术语) | Technical Definition (技术定义) |
|---|---|---|
| (N) | Normen | Conforms to VDE Standard (VDE 0250-813 for Mining/Reeling). 符合VDE标准（矿用/卷盘用 VDE 0250-813）。 |
| TS | Trossen | Heavy Duty / Trailing Cable design. 重型/拖曳电缆设计。 |
| Z | Zugentlastung | High Tensile Strain Relief Element (The focus of this article). 高抗拉应变消除元件（本文的重点）。 |
| C | Chirm (Screen) | Concentric conductor screen (shielding) for field control. 用于电场控制的同心导体屏蔽。 |
| G | Gummi | Rubber Insulation (EPR / 3GI3). 橡胶绝缘 (EPR / 3GI3)。 |
| EW | Einzel Ader / Wirksam | Individual core screening / Earth conductor arrangement. 分相屏蔽 / 接地导体排列。 |
| Ö | Ölbeständig | Oil Resistant outer sheath. 耐油外护套。 |
| U | Unflammable | Flame retardant sheath (PCP / 5GM5). 阻燃护套 (PCP / 5GM5)。 |
3. The Physics of Tensile Strength: Why Copper Isn’t Enough
Standard copper conductors (Class 5 or 6) have a limited mechanical tensile strength. According to VDE 0298 standards, the maximum safe tensile load for copper is 15 N/mm² (dynamic) to 50 N/mm² (static total break). In applications involving long vertical suspensions (like spreaders) or high-speed horizontal reeling, the weight of the cable itself plus the acceleration forces can easily exceed the yield point of copper.
标准铜导体（第5类或第6类）的机械抗拉强度有限。根据 VDE 0298 标准，铜的最大安全拉伸载荷为 15 N/mm²（动态）至 50 N/mm²（静态断裂）。在涉及长垂直悬挂（如吊具）或高速水平卷绕的应用中，电缆自重加上加速度力很容易超过铜的屈服点。
Without “Z”: Max Load ≈ Total Copper Cross Section × 15 N/mm²
With “Z”: Max Load ≈ Strength of Aramid/Steel Element (e.g., > 20,000 N)
With “Z”: Max Load ≈ Strength of Aramid/Steel Element (e.g., > 20,000 N)
The Risk of “Copper Elongation” (铜伸长的风险)
If a cable without a “Z” element is stretched beyond its limit, the copper conductors elongate. This reduces their cross-section (increasing resistance) and eventually causes them to snap internally. The “Z” element acts as a mechanical backbone, absorbing the tension so the copper remains stress-free.
如果没有任何“Z”元件的电缆被拉伸超过其极限，铜导体会伸长。这会减小其截面积（增加电阻），并最终导致其内部断裂。“Z”元件充当机械骨架，吸收张力，从而使铜导体保持无应力状态。
4. Material Engineering: Aramid vs. Steel
At Anhui Feichun Special Cable Co., Ltd., we utilize two primary materials for the “Z” element, depending on the application scenario:
在安徽飞纯特种电缆有限公司，我们根据应用场景，主要使用两种材料作为“Z”元件：
| Material (材料) | Key Characteristics (主要特性) | Typical Application (典型应用) |
|---|---|---|
| Aramid Fibers (Kevlar®) 芳纶纤维 | Extremely high strength-to-weight ratio. Lightweight, non-conductive, and highly flexible. Does not corrode. 极高的强度重量比。轻便、不导电且高度柔韧。不腐蚀。 | Vertical Spreaders (Spreader Cables). High-speed vertical movement where minimizing cable weight is crucial. 垂直吊具（吊具电缆）。 对应电缆重量至关重要的高速垂直运动。 |
| Steel Rope (Galvanized) 钢丝绳（镀锌） | Highest absolute tensile strength. Heavier and stiffer than Aramid. Can impact bending radius. 最高的绝对抗拉强度。比芳纶更重且更硬。可能会影响弯曲半径。 | Deep Mining Shafts. Extremely long vertical drops where absolute break strength is the priority over speed. 深矿井。 绝对断裂强度优先于速度的极长垂直落差。 |
5. Key Application Scenarios
A. Vertical Basket / Spreader Operations (垂直吊篮/吊具操作)
Container cranes (STS) use spreaders that lift and lower rapidly. The control and power cable must follow this movement. Gravity acts on the suspended length of the cable. A standard (N)TSCGEWÖU (without Z) would stretch and break under its own weight at lengths exceeding 50-80 meters. The (N)TSZCGEWÖU transfers this weight to the central Z-element.
集装箱起重机（STS）使用快速升降的吊具。控制和动力电缆必须跟随此运动。重力作用于电缆的悬挂长度。标准的 (N)TSCGEWÖU（无 Z）在长度超过 50-80 米时，会在自重作用下被拉伸并断裂。(N)TSZCGEWÖU 将此重量转移到中央 Z 元件上。
B. High-Speed Horizontal Reeling (高速水平卷绕)
In horizontal applications (like gantry cranes) with high acceleration (> 1 m/s²), the inertia of the cable reel creates significant tension spikes (snatch loading). The “Z” element protects the conductors from these sudden jerks.
在具有高加速度（> 1 m/s²）的水平应用（如门式起重机）中，电缆卷盘的惯性会产生显著的张力峰值（抓举载荷）。“Z”元件保护导体免受这些突然冲击的影响。
6. Manufacturing Precision at Anhui Feichun
Manufacturing a cable with a central strain relief requires specialized extrusion techniques. The “Z” element must be perfectly centered. If it is off-center, the tensile load will be distributed unevenly, causing the cable to corkscrew (twist) during operation. Anhui Feichun uses laser-guided centering during the cabling process to ensure the Torsion-Free performance of our (N)TSZCGEWÖU cables.
制造带有中央应变消除元件的电缆需要特殊的挤出技术。“Z”元件必须完美居中。如果偏离中心，拉伸载荷将分布不均，导致电缆在运行过程中发生螺旋变形（扭曲）。安徽飞纯在成缆过程中使用激光导向定心，以确保我们的 (N)TSZCGEWÖU 电缆具有无扭转性能。
- Breaking Load Testing: Every batch is tested to verify the breaking load of the Z-element (e.g., > 10kN, > 25kN depending on size).
- Sheath Adhesion: The inner sheath is pressure-extruded to lock the Z-element in place, preventing it from slipping inside the cable.
