Selection of variable frequency motor cables

May I ask what the difference is between special frequency conversion cables and ordinary cables?

The three large and three small conductors are arranged symmetrically to form the cable. For cables designed specifically for 6/10 kV variable-frequency motors, this cable structure differs from that of ordinary 6/10 kV power cables. In ordinary power cables, three insulated conductors are shielded with copper tape before being bundled together, whereas in cables intended for variable-frequency motors, the conductors are first shielded with copper wires and tape, after which phase-specific sheaths are extruded around them; the conductors are then bundled symmetrically. The symmetric cable structure, thanks to the interchangeability of the conductors, offers better electromagnetic compatibility, which helps to suppress electromagnetic interference. It enables the cancellation of odd-frequency components among higher harmonics, thereby enhancing the interference resistance of these cables and reducing electromagnetic radiation throughout the system. I. Shielding structure: Variable-frequency cables generally adopt a total shielding structure, which includes combinations of copper wire strips for shielding, copper strip shielding, and copper wire braided shielding; moreover, the cross-sectional area of the shielding layer is in a certain proportion to that of the core. Such a design enables the variable-frequency cable to have good resistance to electromagnetic induction, as well as to interference from signals transmitted by the power supply. It also helps to reduce inductance to a certain extent, thereby preventing excessive induced electromotive forces. This shielding layer also serves to suppress the emission of electromagnetic waves, thereby protecting the wire core. Ordinary cables do not have such a shielding layer, and thus they have weaker interference resistance. II. Electrical Properties: Frequency conversion cables have additional requirements regarding capacitance and inductance properties compared to ordinary cables. Their electrical properties can be designed according to actual usage needs, enabling the cables to better meet the requirements of their intended use and eliminating certain interference factors. III. Manufacturing Process: During the production of frequency conversion cables, compared to ordinary cables, these require processes such as extruding the insulated core and stranding the cables. The former directly affects the electrical properties of the cable. Therefore, in order to improve the performance of these cables, high-quality materials are used, and great attention is paid to the purity of the raw materials during manufacturing. The extrusion process must be carried out carefully and precisely, with attention paid to ensuring that the insulation eccentricity is consistent with the outer diameter of the insulation. This approach helps to minimize interface effects, thereby further enhancing the electrical performance of frequency conversion cables. IV. Cable symmetry: Variable frequency cables require a symmetric design. Generally, ordinary cables consist of three insulated conductors that are shielded with copper tape to form the cable, whereas variable frequency cables use copper wires covered with phase-specific sheaths before being structured in a symmetric manner; this gives them better interchangeability, improved electromagnetic compatibility, and enhanced resistance to interference.

For a length of 50m, ordinary cables are more than sufficient; whether the inverter is equipped with an output reactor or DU/DT or not, frequency conversion cables help prevent harmonics from interfering with surrounding electronic devices. However, they are not as effective for motor starting and operation as ordinary cables, as they increase the capacitive component relative to ground under the influence of harmonics.

Cable model: ZC-BPYJVP-0.6/1KV 3*50+3*10 (ZC denotes a flame-retardant cable; it can be omitted if not required)

You can refer to the manual for the ABB frequency converter; generally, for a frequency converter of this size, ordinary cables are sufficient.

I agree with you, but I’ll choose the 70-square-meter one

50 meters – such a short distance; a regular four-core cable is sufficient

We often use 75KW variable-frequency motors; for lengths of 50 meters, ordinary cables are sufficient. A cable of type ZR-YJV22--3X70+1X35 is enough. Some applications upstairs use 50-square-millimeter cables, but I think that’s a bit risky. After all, cable manufacturers guarantee that their products meet national standards, but it’s possible that these cables may not be adequate for such uses. I hope this helps you