Engineering Analysis: How does (N)GRDGÖU (Flat Rubber Cable) handle heat dissipation differently than round cables in festoon systems?
Published by: Anhui Feichun Special Cable Co., Ltd.
Specialists in Industrial Power Transmission and Thermal Management of Cables
1. Executive Summary: The Geometry of Cooling
2. Physics of Heat Dissipation: Flat vs. Round
Round Cables: When current flows through a conductor, heat is generated ($I^2R$ losses). In a round cable, the insulation is uniformly thick around the core. As heat radiates outward, it meets the ambient air. However, the geometric center of a round cable is equidistant from the cooling surface.
Flat Cables ((N)GRDGÖU): The cores are laid parallel in a single plane. This means no conductor is buried deep in the center of a bundle. Every conductor is adjacent to the outer sheath, providing a direct thermal path to the cooling air.
圆形电缆： 当电流流过导体时，会产生热量（$I^2R$ 损耗）。在圆形电缆中，绝缘层在芯线周围均匀分布。当热量向外辐射时，它会遇到环境空气。然而，圆形电缆的几何中心与冷却表面的距离是相等的。
扁平电缆 ((N)GRDGÖU)： 芯线在同一平面上平行铺设。这意味着没有导体被深埋在束的中心。每个导体都与外护套相邻，为冷却空气提供了直接的热通道。
| Parameter (参数) | Bundled Round Cables (圆形电缆束) | (N)GRDGÖU Flat Cable (扁平电缆) |
|---|---|---|
| Heat Trap Effect 热聚集效应 | High. Inner cables in a bundle heat up neighboring cables. | Low. Cores are spread out; no core is surrounded by other hot cores on all sides. |
| Cooling Surface Area 冷却表面积 | Reduced effectively when bundled (cables touch each other). | Maximized. Both top and bottom surfaces are exposed. |
| Derating Factor (Grouping) 成组降容系数 | Significant derating required (often 0.48 – 0.70). | Minimal derating required (often 0.85 – 1.0 depending on spacing). |
3. The “Stacking” Advantage in Festoon Systems
A. Airflow Gaps (气流间隙)
When round cables are used in a trolley, they are often thrown together in a chaotic “basket” or tied in a tight circular bundle. This eliminates airflow between cables. Flat cables, however, are stacked. Even when stacked, the rectangular profile ensures that the stack remains stable, and spacers can easily be introduced to create ventilation gaps.
当在小车中使用圆形电缆时，它们通常被杂乱地扔进“吊篮”或捆成紧密的圆形束。这消除了电缆之间的气流。然而，扁平电缆是堆叠的。即使在堆叠时，矩形轮廓也能确保堆叠保持稳定，并且可以轻松引入垫片以产生通风间隙。
B. VDE 0298-4 Grouping Factors (VDE 0298-4 成组系数)
According to DIN VDE 0298-4, the current carrying capacity must be reduced when cables are grouped.
For round cables touching each other, the factor can drop to 0.48 (meaning you lose 52% of capacity).
For flat cables, even when stacked without spacing, the factor is typically higher because heat can still escape from the edges. If separated by a distance equal to their thickness, the factor is 1.0 (No loss).
根据 DIN VDE 0298-4，当电缆成组时，必须降低载流量。
对于相互接触的圆形电缆，该系数可能降至 0.48（意味着您损失了 52% 的容量）。
对于扁平电缆，即使在没有间距的情况下堆叠，该系数通常也更高，因为热量仍然可以从边缘逸出。如果以等于其厚度的距离分隔，该系数为 1.0（无损耗）。
4. Why (N)GRDGÖU specifically?
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Insulation Material: We use a high-grade EPR (Ethylene Propylene Rubber) that can withstand operating temperatures of 90°C, compared to standard rubber which is limited to 60°C. This allows for a higher thermal delta.
绝缘材料： 我们使用高等级 EPR（乙丙橡胶），可承受 90°C 的工作温度，而标准橡胶仅限于 60°C。这允许更高的热温差。 -
Sheath Conductivity: The Polychloroprene (PCP) outer sheath is formulated not just for mechanical toughness, but for thermal conductivity, aiding the transfer of core heat to the surface.
护套导热性： 氯丁橡胶 (PCP) 外护套的配方不仅为了机械韧性，还为了导热性，有助于将芯线热量传递到表面。
5. Comparison Case Study: 4x25mm² System
Consider a crane requiring 100 Amps. Let’s compare the thermal footprint.
| Scenario | (N)GRDGÖU Flat 4x25mm² | Round Rubber 4x25mm² |
|---|---|---|
| Configuration | Stacked (3 cables high) | Bundled (Triangular) |
| Surface Area Exposed | ~60% of surface (Sides + Top/Bottom of stack) | ~30% of surface (Outer perimeter only) |
| Core Temperature | Maintains < 80°C | Likely > 90°C (Requires larger cable) |
| Result | Safe Operation | Potential Overheating / Insulation Aging |
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