Main production technology of wire and cable

The energy-saving effect of the frequency conversion device is very obvious. The variable-frequency speed control motor is used in the high-power motor, and the entire generator set can save energy by 30%. After variable-frequency speed control is used, the soft start of the motor is realized to ensure smooth operation of the motor, reduce the wear and tear of the motor bearing, and prolong the service life and maintenance cycle of the motor. Therefore, variable frequency speed control technology is widely used in petroleum, metallurgy, power generation, railway, mining and other industries.

1. Cable symmetry Design

For 1.8/3 kW and below variable frequency motor dedicated cables, and symmetric 3 + 1 core and 4 Core Cables can only be used for the input of the main power supply, but it is best to use symmetric structure cables. The inverter and variable-frequency motor cable must adopt a symmetric cable structure. The symmetric cable structure includes three cores and three + three cores, the 3 + 3-core cable structure is to divide the fourth core (neutral core) of the three large and small four-core insulated wire cores into three insulated wire cores with smaller cross-section, and symmetric the three core Cables into cables, for 6/10 kV Inverter Motor cables, the cable structure is different from that of 6/10 kV common power cables. The common power cables shield three insulated wire cores with copper tape and form cables, the dedicated cables for variable-frequency motors are shielded by copper wires and then packaged into phase sheaths. symmetric cable structures have better electromagnetic compatibility due to wire swapping, it plays a role in suppressing electromagnetic interference, can offset the odd frequency in the higher harmonic, improve the anti-interference performance of the dedicated cables of the variable frequency motor, and reduce the electromagnetic radiation in the whole system.

2. Design of Shield Structure

The shielding of cables for 1.8/3kV or lower frequency conversion Motors generally adopts the total shielding mode. The shielding of cables for 6/10 kV Frequency Conversion motors is composed of phase blocking and total shielding, split-phase shielding generally can use copper tape shielding or copper wire copper tape combination shielding. The total shielding structure can adopt copper wire combination shielding, copper wire braided shielding, copper tape shielding, copper wire braided copper tape shielding, etc. The Screen Layer Section and the main line core section according to a certain proportion. The shielded cables in this structure can resist electromagnetic induction, poor grounding, and interference from power cord conduction, reduce inductance, and prevent excessive induction potential. The shielding layer can not only suppress the external launch of electromagnetic waves, but also act as a channel for short-circuit current, and can protect the Neutral Wire Core. 6/10 kV Inverter Motor dedicated cable, considering that the cable is often subjected to radial external force during use, add the galvanized steel strip pin installation layer outside the cable shield layer (add the isolation sleeve between the shield layer and the steel strip pin installation layer ). The steel strip pin is mainly used as the radial mechanical protective layer of the cable. At the same time, it also plays a general shielding effect, especially for steel armor, copper wire, and copper tape shielding. It uses two different shielding materials, electromagnetic Shielding plays a complementary role, and the shielding effect will be better.

3. Cable electrical performance design

1.8/3kV and below frequency conversion motor dedicated cable electrical performance are designed in accordance with GB/Tl2706, 2008 standard. In addition to the GBT/l2706.2008 standard, the dedicated cables for 6/10 kV motor increase the electrical performance requirements such as capacitance and inductance. According to the actual usage of the dedicated cable for the variable frequency motor, the electrical performance parameters of the cable are determined according to the technical conditions of the power transmission cable of GB/T 12706.2008 and ABB daily.

4. Main Cable Manufacturing Technology

In the production process of dedicated cables for variable-frequency motors, the insulation core packing process and cable forming process are the most critical processes.

The quality of the insulation Wire Core directly affects the electrical performance of the cable. To improve the quality of cables, we choose high-performance insulation materials for production, such as 1.8/3kv Variable-Frequency Motor special cables, using 10 kV cross-linked insulation materials, 6/10 kV Inverter Motor cables use 35kv cross-linked insulation material, conductor shielding, insulation shielding and insulation materials are imported materials. In the production process, we pay special attention to the purification of raw materials, shielding and insulation material packing tight, control insulation eccentric and Insulation Outer diameter even consistent, this can reduce the interface effect, improves the electrical performance of cables.

The structure of variable frequency cables in Cabling Process is symmetric. The tension of the insulation core must be uniform during cabling so that the length of the cable core should be consistent as much as possible. Otherwise, the structure may change, resulting in non-uniformity of capacitance and inductance, affecting the electrical performance of the cable.