High voltage cables are a kind of power cable, that refers to the power cable used to transmit between 1kv-1000kv, mostly used in power transmission and distribution.
And high-voltage cables are very common in daily life, from big factory workshops to small home appliances and so on.
For high-voltage cables, people will also have many questions, such as: what exactly is a high-voltage cable? What are its characteristics? In life, how do we go to prevent high-voltage cable problems?
What is a high voltage cable?
The components of a high voltage cable from the inside out include conductor, insulation, inner sheath, filler (armor), and outer insulation.
Of course, the armored high-voltage cables commonly used in general are mainly used for underground burial, which can resist high-intensity compression on the ground, and at the same time can prevent other external damage.
Classification of HV cables
1 YJV cable full name cross-linked polyethylene insulation PVC sheathed power cable (copper core)
2 VV cable is called PVC insulated PVC sheathed power cable (copper core)
3 YJLV cables are cross-linked polyethylene insulated PVC sheathed aluminum core power cables.
4 VLV cable full name polyvinyl chloride insulation PVC sheathed aluminum core power cables
Due to the excellent electrical conductivity of copper conductors, more and more projects use copper-core power cables as the backbone of the power supply system.
The application of aluminum-core power cables is less, especially in the more high-voltage power systems, the more copper-core cables are chosen.
Comparison of high-voltage cables and medium-voltage and low-voltage cables
High voltage cables, medium-voltage cables, and low voltage cables are crucial components of our electrical infrastructure.
The Voltage Level is Different
First, we can see from the name that the voltage index of these three cables is different. High voltage refers to the cable voltage class within the range of 35 kV-110 kV. Low voltage refers to the cable voltage class within the range of 0.6 kV-1 kV. So the medium voltage cable naturally refers to the 3 kV-35 kV.
Identify Low Voltage Lines
Outdoor low-voltage line has several distinct features:
1 The basic use of cement rod support, and the cement rod is short, generally not more than 5 meters.
2 Wire thickness is the same, and the number of multiple is 4, this is because low voltage wire generally uses a three-phase four-wire system.
If these features are available, the wire voltage of the wire is 380 volts and the phase voltage is 220 volts.
Identify the Medium and High Voltage Lines
Medium and high voltage lines also have obvious features:
1 If the thickness of the wire is the same, the number is a multiple of 3, this is because the transmission wire generally uses three-phase transmission, if there are these characteristics, the wire can be basically determined to be 10,000 volts.
2 If the thickness of the wire is not the same, then the number of thick lines is a multiple of 3, and there are only two thin lines, and it is assumed that at the highest point.
This is because thin lines are not used for transmission, but for lightning protection, also known as lightning protection lines.
If these characteristics are present, the wire can be determined to be a high-voltage line.
Further, identify the high-voltage wires
In order to improve the transmission capacity, the high voltage wire generally uses split wire.
Generally speaking, is the original phase of a wire, now with several wiring harnesses together to replace the original wire. Knowing this, it is easy to tell the voltage level of the wire.
- A phase of a line is 110,000 volts;
- One phase and two lines are 220,000 volts;
- Four lines in one phase are 500,000 volts.
However, these cables can encounter a series of problems. Whether you’re dealing with a low voltage overhead line or a submarine MV cable, understanding these issues is vital.
Recognizing HV Cable Common Problems
One of the most common problems with high voltage cables is aging and degradation. This can be a result of varied factors such as environmental exposure and stress from electrical load.
Besides, if you’re dealing with an insulation cable, wear and tear may lead to insulation failure, posing a significant risk.
Insulation Failure: What’s the Root Cause?
Insulation failure in high voltage cables often has two main causes – physical damage and electrical stress.
Physical damages might include cuts or abrasions, which allow moisture to seep in, compromising the insulation properties.
On the other hand, electrical stress can cause over stressing of the insulation, leading to partial discharges and eventual failure.
Long-term operation due to thermal expansion and cold contraction, electrolytic corrosion or chemical corrosion, resulting in sealing aging, lead sheath wear or crack, so that local insulation damage, moisture or deterioration.
Cable is directly affected by external forces, such as excessive bending, ground subsidence and bear excessive tension. The above can cause cable damage because the vibration can cause metal sheath fatigue damage.
Armored Cable and Control Cable Concerns
For specialized cables like armored cables and control cables, other issues might arise. For instance, armored cables, designed to be robust and protect against mechanical damage, can decay or dent. Control cables, on the other hand, might experience signal interference due to improper grounding or shielding.
The Intricacies of High Voltage Overhead Lines and Submarine HV Cables
Granted, less common issues might arise in specific types of cables. For instance, high voltage overhead lines might experience bird strikes, lightning strikes, or broken conductors. In comparison, submarine HV cables might deal with marine activities or abrasive seafloor conditions, causing mechanical stresses.
High, medium, and low voltage cables, alongside special cases like submarine HV cables, each have their unique challenges.
By understanding these common problems and their root causes, we’re one step closer to ensuring a more efficient and reliable electrical infrastructure.
Understanding common problems with high voltage cables not only showcases electrical-savvy keenness but an improvement towards a safer and more efficient output.
Are you ready to take charge and make a difference?