In the field of industrial automation and energy-saving transformation, high-voltage variable frequency cables serve as the core components connecting variable frequency power supplies and variable frequency motors, and their performance directly affects the stability and efficiency of the system. withBPYJVT-8.7/15KVTaking high-voltage variable frequency cables as an example, their structural design integrates electromagnetic compatibility, voltage shock resistance, and mechanical protection, becoming a key infrastructure for medium to high voltage variable frequency transmission systems.

1、 Composite shielding structure: multi-layer protection to suppress electromagnetic interference

BPYJVT-8.7/15KVThe cable adopts copper tape shielding+Copper wire winding/The composite shielding system of copper tape wrapping forms a dual electromagnetic protection:

Phase separation shielding layer: Each insulated wire core is covered with a copper strip shielding layer, effectively blocking the interference of high-order harmonics generated by single-phase current on adjacent wire cores. For example, in the output of a frequency converterPWMDuring wave time, phase separation shielding can reduce odd harmonics (such as...)3Secondly5The coupling effect of subharmonics reduces the distortion rate of motor terminal voltage.

Total shielding layer: Three wire cores are wrapped with copper tape and copper wire as a whole to form360Fully enclosed shielding structure. This design can suppress common mode interference and prevent electromagnetic waves from radiating outward. The measured data shows that its shielding transmission impedance is100MHzWithin the frequency band ≤1Ω/mSatisfyIEC 60502Rated voltage30kVElectromagnetic compatibility requirements for extruded plastic insulated power cables and below.

Proportional design: The cross-sectional area of the shielding layer is kept in a fixed proportion with the cross-sectional area of the main core, ensuring that the shielding layer can act as a barrier when short-circuit current passes throughPEThe use of grounding wire cores balances electromagnetic protection and safety grounding functions.

2、 Symmetric Three Core Structure: Optimizing Electromagnetic Balance and Transmission Performance

Compared to traditional four core cables（3phase+1The neutral line is different,BPYJVT-8.7/15KVAdopting a symmetrical three core design, its core advantages lie in:

Electromagnetic field balance: Three wire cores present120Isometric twisting forms a true concentric structure. This layout can counteract the magnetic field superposition effect generated by three-phase currents and reduce the unevenness of system impedance. for example, in6/10kVIn variable frequency motor drive, the symmetrical structure ensures that the capacitance deviation rate is ≤3%Inductance deviation rate ≤5%Significantly better than four core cables10%The above deviations.

Harmonic suppression capability: Symmetrical structures can cancel out odd frequency components in high-order harmonics through wire interchangeability. Tests have shown that the output voltage of the frequency converter contains25%The total harmonic distortion rate of the motor terminal voltage of a symmetrical cable during harmonic generation（THD）Reduced compared to four core cables40%.

Mechanical stability: The gap between the wire cores is filled with weather resistant and temperature resistant resin to enhance vibration resistance, suitable for industrial scenarios such as metallurgy and mining where mechanical impact exists.

3、 High performance material system: adaptableextremeworking condition

Conductor and insulation layer: using high-purity oxygen free copper conductor (conductivity)≥97% IACS）Cross linked polyethylene（XLPE）Insulation, allowing conductors to operate continuously at temperatures up to90℃, during short circuit（5sThe temperature inside has risen250℃, far beyond ordinaryPVCcable70℃/160℃ standard.

Sheath material: The outer sheath is made of flame-retardant polyvinyl chloride（PVC）Oxygen index ≥32%, throughGB/T 18380.3Single vertical combustion test, suitable for indoor environments with fire risks.

Bending performance: The bending radius of the cable is the diameter12Double (fixed installation) or6Multiple (flexible cable) to meet the installation needs in narrow spaces. For example, in railway traction systems, cables can be bent along the track without damaging the internal structure.

4、 Typical application scenarios and energy-saving benefits

BPYJVT-8.7/15KVCables are widely used in fields such as papermaking, metallurgy, and rail transit, with significant advantages in energy efficiency and reliability

Motor efficiency improvement: By adopting variable frequency speed regulation in high-power motors, the comprehensive energy-saving rate of the system can reach30%For example, after the transformation of the rolling mill drive system in a certain steel enterprise, the annual energy savings exceeded200ten thousandkWh.

Extended equipment lifespan: Soft start function reduces motor bearing wear and extends maintenance cycle50%The above.

Enhanced system stability: Symmetrical structure and composite shielding can reduce motor noise5-8dBReduce torque fluctuations30%Suitable for precision machining equipment.

5、 Standards and certifications: comply with international standards

This cable is strictly implementedGB/T 12706.2Rated voltage1kVto35kVNational standards such as "Extruded Insulated Power Cables and Accessories" and reference to themIEC 60502TheDL 401Design according to international standards such as the "Guidelines for the Selection of High Voltage Cables" to ensure compliance-40℃ to+90Stable operation within a wide temperature range of ℃.

Conclusion

BPYJVT-8.7/15KVThe high-voltage variable frequency cable achieves the unity of electromagnetic compatibility, voltage shock resistance, and mechanical reliability through composite shielding, symmetrical three core structure, and high-performance materials. Its technical indicators not only meet the domestic industrial demand, but also achieveinternationalThe level provides reliable assurance for the efficient operation of the variable frequency drive system.