Briefly analyze the characteristics of inverter cables and the problems that need to be overcome in the design

What is a frequency converter cable?

In layman's terms, frequency conversion cable is mainly used for the connection between frequency conversion power supply and frequency conversion motor with cable, frequency conversion cable has a broad application field, suitable for mining, metallurgy, papermaking, railway, food processing and metal processing and other industries
.

So what is the biggest difference between frequency conversion cable and ordinary cable?

First of all, the frequency conversion cable works in a special environment, and its operating frequency adjustment range is wider, which will lead to its work regardless of the high or low working frequency, it will have a waveform profile of the main frequency, and at the same time will contain many high-order harmonics, after multiple times of reflection amplitude superposition, its withstand voltage can reach several times
the working voltage.
Under such working conditions, if the insulation safety factor of the frequency conversion cable is not high enough, it is very easy for the cable to be broken down, resulting in a series of safety accidents and huge losses
.

Secondly, we can think that the cable will emit electromagnetic waves to pollute
the outside world under working conditions.
Especially in the industrial field, this phenomenon can be widely seen, mainly because the motor power is relatively large, and the cable length between the inverter power supply and the inverter motor is also relatively long
.
This leads to the fact that the cable is like an effective carrier that emits high-frequency electromagnetic waves outward in the working state, which is called electromagnetic wave environmental pollution
.

What problems do we need to overcome when designing inverter cables?

First of all, the problem that needs to be overcome is that ordinary cables may be broken down
within a few hours under variable frequency conditions.
After analysis, it can be concluded that the occurrence of this phenomenon is by no means caused by insulation aging, but can be attributed to the influence of high-frequency pulse voltage on insulation
.
Therefore, the selection of insulation materials in cable design is very important, analyzing common cable materials we can know that PVC insulation often because of its dielectric loss and accelerate insulation breakdown, cross-linked polyethylene insulation has both thermal, electrical, mechanical and other excellent properties, so we choose cross-linked polyethylene as the insulation material
of frequency conversion cable.
At the same time, we can also properly thicken the insulation thickness when designing the cable insulation thickness, so that the frequency conversion cable is safer and more reliable
.

Second, we need to solve the problem of
environmental pollution of high-frequency electromagnetic waves.
Taking four-core low-voltage cable as an example, we can first reduce the pollution
of high-frequency electromagnetic waves to the environment by improving the arrangement of insulated cores.
If the three main cores of the cable and the ground core are directly cabled, the magnetic field generated by the harmonic current will be asymmetrical; The ground core is decomposed into three insulated cores with small sections, and the three small cores are symmetrically formed into cables, which can basically symmetricize the magnetic field and reduce the interference
of the magnetic field to the outside.
Secondly, the shielding structure should be strengthened, and it is generally customary to use copper wire braided shielding, in fact, the shielding structure material consumption is large, the processing speed is slow, and the shielding effect is not ideal
.
In order to achieve a better shielding effect and facilitate production, the copper strip shielding and copper wire braided structure are adopted, which can effectively suppress the external emission
of electromagnetic waves.