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23 Min Read
The shield transfer impedance (STI) for (N)TSCGECEWÖU 12/20kV cables with individual concentric copper screens is approximately 0.005–0.012 Ω/m at 50/60 Hz power frequency, representing the electrical impedance that coupling currents encounter as they attempt to penetrate the copper screen and reach the main conductor. At higher frequencies relevant to VFD variable switching (around 10 kHz), the STI increases slightly to approximately 0.008–0.015 Ω/m due to skin-effect limitations in the copper conductors. At even higher frequencies extending into the megahertz range (1–10 MHz) where harmonic emissions and EMI are most problematic, the STI rises further to approximately 0.02–0.08 Ω/m depending on the copper screen material properties and frequency-dependent conductor resistance. The shielding effectiveness, measured as the attenuation in decibels (dB) of external electromagnetic fields trying to couple energy into the cable conductors, is typically 60–80 dB at 100 kHz and remains above 40 dB even at 1 MHz, demonstrating excellent EMI rejection across the industrial frequency range. These metrics establish that individual concentric copper screens provide substantially superior EMC performance compared to traditional overall braided screens, particularly in reducing conducted emissions in VFD-driven machinery where rapid voltage switching and harmonic currents create severe electromagnetic stress on nearby control cables and sensitive electronic systems.
Technical Department
on27/02/2026

Shield Transfer Impedance: What are the exact EMC performance parameters and screening effectiveness metrics for (N)TSCGECEWÖU 12/20kV individually screened medium-voltage flexible cables in industrial and VFD applications? 

The shield transfer impedance (STI) for (N)TSCGECEWÖU 12/20kV cables with individual concentric copper screens is approximately 0.005–0.012…
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19 Min Read
The maximum continuous ampacity for AmerCable 37-105319BS 8kV marine medium-voltage cable is 152 amperes when operating as a single conductor run in free air at the IEEE 45 standard reference conditions (45°C ambient temperature, 90°C conductor operating temperature). For multiple-conductor installations in cable trays typical of FPSO and offshore platform electrical systems, the ampacity derates to approximately 129 amperes due to reduced cooling efficiency when cables are bundled together. These ratings represent the maximum continuous current the cable can safely carry indefinitely without exceeding the 90°C maximum permissible conductor temperature specified by the cable's EPR (ethylene propylene rubber) insulation. The 152-ampere reference rating emerges from a careful balance between the cable's thermal conductivity, the copper conductor's heat-carrying capacity, the insulation's thermal stability, and the international standardization process that created IEEE 45 to ensure safe and consistent marine cable performance worldwide. The approximately 15% reduction from the single-conductor 152 amperes to the cable-tray 129 amperes reflects the real-world constraint that when multiple cables are installed side-by-side in ventilated tray systems, the outer surfaces of adjacent cables create a partial thermal barrier, reducing the ability of each individual cable to dissipate I²R losses to the surrounding environment. Understanding these two ampacity values and the conditions under which each applies is essential for safe electrical system design on ocean-going vessels and offshore platforms.
Technical Department
on27/02/2026

Maximum Continuous Ampacity: What is the current-carrying capacity for AmerCable 37-105319BS 8kV marine medium-voltage cable under IEEE 45 standards?

The maximum continuous ampacity for AmerCable 37-105319BS 8kV marine medium-voltage cable is 152 amperes when operating as a single conductor…
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17 Min Read
Type SHD-GC 3/C #1 AWG 8kV trailing cable is approximately 0.410 Ohms/km at 20°C reference temperature for a single conductor, calculated from the copper's material resistivity combined with the #1 AWG conductor cross-section (approximately 42.4 mm² or 53,486 circular mils). This resistance value increases to approximately 0.495 Ohms/km at 90°C operating temperature due to copper's positive temperature coefficient of resistance. For a complete three-phase circuit using this cable type, the total circuit resistance including all three phase conductors but excluding the ground return path is approximately 0.410 Ohms/km at 20°C or 0.495 Ohms/km at 90°C. When operating a mine shovel or dragline drawing 150–160 amperes over a typical 1,000-meter (1 km) cable run from the mine substation to the equipment, the three-phase voltage drop across this cable is approximately 55–70 volts at the reference condition, representing a drop of roughly 0.75–1.0% from the 8,000-volt nominal supply. This voltage drop magnitude is acceptable for most mining equipment applications and remains within typical power system design standards that permit up to 2–3% voltage drop on secondary feeder circuits. The physical mechanism behind this resistance is the collision of free electrons within the copper lattice structure, where random thermal motion of atoms creates an effective "friction" that opposes electron flow, converting electrical energy into heat at a rate proportional to I²R.
Technical Department
on27/02/2026

Voltage Drop Calculation: What is the DC resistance (Ohms/km) for Type SHD-GC 3/C #1 AWG 8kV trailing cable? 

Type SHD-GC 3/C #1 AWG 8kV trailing cable is approximately 0.410 Ohms/km at 20°C reference temperature for a single conductor, calculated from…
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