Vania Welker спросил 2 года назад
Precautions For High Voltage Installation
High voltage domestic electrical Installations — polaroid.wiki, power lines are often located on utility poles but they can also be buried. Whatever the location you work in it is essential to know the proper precautions when working with high voltage electricity.
The biggest danger is an electric shock. This could cause serious injuries or even death.
Insulation
Insulation is an essential component of high voltage installations. It must be maintained at the correct levels to avoid malfunction and electric shocks. It acts as a barrier between the electrodes of a device and other components of the circuit, making it difficult for someone to touch them directly, which could lead to injury or death.
Insulators can be constructed from a variety of materials. The most popular was rubber material due to its simplicity to make and could stand up to the harshest conditions. Plastics have replaced rubber as the primary material in high-voltage applications.
Certain plastics are more resilient than others. You should carefully consider the properties of each material before deciding on which is best suited for your project. Specifically, you need to know the strength of each, how durable it is as well as its flexibility and how it fares with abrasion and moisture.
Chemical and domestic electrical installations thermal properties are also important. Knowing the resistance to acid and alkalis and the capability to withstand extreme temperatures and how it will absorb water are all factors that will help you determine the best material for your application.
You should ensure that the insulators are resistant to heat and pressure when used in high voltage settings. It is recommended to select an item that can withstand temperatures up to 1000°C and humidity up to.
In addition, you should always look for insulation that is resistant to fire and other hazards. This could be a material that can resist sunlight and ozone, is waterproof, and resistant to chemical and oil.
It is also crucial to find insulations that are made to withstand the extreme tensions associated with power transmission. These can be suspension insulators as well as shackle insulators, strain insulators.
These insulators can be used to protect power lines from sharp corners or dead ends. Based on the line’s voltage, these insulators can be comprised of a number of porcelain or glass discs, which are joined in series by metal links.
Sharp Points
Using a conductor with sharp edges and points increases the chance of dielectric breakdown in the event of a high voltage spike. Fortunately, most manufacturers are wise to this issue and have made a point of using heat-shrink tubing that has adequate dielectric strength. A well-designed system can take steps to limit the risk of poorly trimmed insulation, which is a common problem for high-voltage installers.
A best practice to ensure a safe, successful installation services is to use an experienced contractor. The most reliable contractors have a well-constructed safety program in place and are well versed in avoiding the hazards that come with high voltages. The most challenging part of this process is to ensure that every member of the crew knows the job they are assigned and is well-versed of the jargon used in high-voltage installations.
Dust
In order to ensure the safety of personnel and prevent injury, it is crucial to ensure that dust doesn’t enter high voltage installations. This can be accomplished by using a dust tight construction. It is also recommended that a protective cover be used on the insulation.
High voltage equipment generally makes use of metal dust and insulation fibers. This is because they share similar characteristics in discharge and movement and a small amount dust can greatly reduce the breakdown voltage of an air gap.
However, the impact of these two impurities on the breakdown of an air gap remains an unknown. A series experiments were conducted to understand the motion and discharge behavior of these materials.
Figure 10 shows that the lifting voltage for metal dust fluctuates with decreasing particle sizes but the movement law is the same. If the voltage is lower than 7 kV the particles move mainly to the upper electrode. They bounce violently between electrodes once they reach 14 kV.
A series of tests with cameras that can move at high speeds were carried out to examine the movement and discharge of these materials in greater detail. The results indicate that the movement of metal dust and the fibers that insulate can be separated into three states: Domestic electrical installations close contact Sate, distant sate and jump sate.
When the dust of metal was present in contact sate, it was moved toward the upper electrode and its movement area formed installing a new electricity meter certain columnar dust space between the electrodes. The area had a low concentration of dust.
The insulating fibres on the other hand, did not move when the voltage was low, but they began to rise with the increase of voltage. The resulting jumps between the electrodes were extremely interesting.
During the test, the voltage was increased from -7 kV to -16 KV. The metal dust and insulating fibers began to move quickly. The insulating fibres began to bounce and lift off violently between the electrodes. This caused an abrupt change in their movement. A large number of dust particles were discharged from this region and caused an explosion.
Voltage Breakdown
In the event that an insulator experiences rapid change of its electrical properties, it’s known as breakdown. This occurs when the local electric field strength exceeds the dielectric strength of the material. This can happen in air or any other insulator and could result in burns, shock or fire.
Depending on the material and shape of the object, different voltages could cause breakdown. It is therefore important to test the materials used for installations that require high voltage.
For instance the breakdown voltage of a semiconductor device like a MOSFET is determined by its drain-to-source current. A technique known as gate-current extraction will determine the breakdown voltage.
Another way of measuring the breakdown voltage is to put the sample of material between two electrodes and applying a high voltage to it. The voltage then increases until the material is broken down.
The breakdown voltage of an insulator is based on its material and the distance between the electrodes, and the electric field strength at the point of contact. This is a crucial factor in determining how much voltage can be safely applied to an insulator.
Engineers can utilize dielectric breakdown tests to determine the maximum voltage their designs can handle. It is also used to track changes in the ability of the insulator to resist voltage.
Some conductors, such as aluminum and copper, are more prone to break down than others. For instance, aluminum can be subject to a voltage breakdown of up to 3 kV/mm when exposed to dry air at standard atmospheric pressure. This is why aluminium cable is rated at a much lower voltage than copper.
Other insulators, such as silicon, may have breakdown voltages that can reach 3.5 KV/mm when exposed dry atmospheric air at normal pressure. This is because silicon conducts better at low temperature than aluminum does.
In liquids, breakdown may be caused by bubbles or small impurities. These can cause an electrical field strength that is not linear in the gap between the electrodes, which could increase the breakdown potential.
It is recommended to insulate the conductive surfaces of devices using dielectric materials such as plastic or glass. This can protect against the possibility of disintegrating and the risks that can result from it.
