1. What is over voltage? How is the overvoltage classified?
Due to lightning discharges, system operation, malfunctions or other causes, the voltage in some parts of the power system may increase abnormally and may in some cases exceed the rated voltage at which the electrical equipment is operating normally, causing equipment insulation damage. This voltage-enduring insulation in power systems is called overvoltage.
Over-voltage energy sources according to their different, can be divided into two kinds of atmospheric over-voltage and internal over-voltage.
Atmospheric overvoltage is due to lightning strike power system facilities, lightning induction or lightning overvoltage along the line caused by the invasion of the substation, known as the lightning overvoltage, induced lightning overvoltage and high potential invasion. Because of its energy from the power system, it is also known as the external over-voltage. Atmospheric over-voltage amplitude depends on lightning parameters and lightning protection measures, and the grid voltage is not directly related to the rated voltage. This type of overvoltage has a pulsating nature and generally lasts for only about ten microseconds, but the harm it causes is quite substantial.
Internal over-voltage according to the causes of electromagnetic oscillations, the nature and form of different, can be divided into power over-voltage, over-voltage operation, accident over-voltage and resonant over-voltage. Now over-voltage classification as follows:
2. What is operating over voltage? What are the causes of over-voltage operation?
Accompanying the normal operation of the circuit breaker or disconnector in the power system or the operation of switching the fault, overvoltages generated between the phases of the system, between phases and phases, and between the two contacts of the circuit breaker or disconnector are referred to as operations Overvoltage.
The reason for operating overvoltage is that many devices in the power system are energy storage elements that store the magnetic energy in the inductor and the electrostatic field energy (electrical energy) stored in the capacitor during the interruption of the circuit breaker or disconnector. A conversion, the transition of the oscillation process, caused by the oscillation over-voltage.
Over-voltage operation is characterized by the duration of the lightning over-voltage is usually longer than the short-term transient over-voltage. Generally hundreds of microseconds to 100ms, and decay quickly. It can usually be simulated using standard operating shock waves.
3. Lightning is how to form? What are the hazards?
Lightning is a discharge phenomenon in the atmosphere. Thunderstorm season, thunderclouds in the process of formation of strong friction with the air and gathered from the charge, when the charged clouds near the ground, there is electrostatic induction on the earth, this time under the cloud of the earth induction and thundercloud opposite sex Charge, the two formed a huge "capacitor." The charge distribution in the thundercloud is not uniform, and the electric field strength of the thundercloud to the ground is also different. When the electric field intensity in the charge-intensive area in the cloud reaches 25-30kV / cm, the dielectric strength of the nearby air will break down and a pilot discharge will occur on the cloud. When the path of the pilot discharge reaches the earth, the earth and the cloud create a strong "neutralization", with a large current, called the main discharge. The main discharge temperature of 20000 ℃, will have a dazzling flash, so that the rapid expansion of air, issued by the roar of the ears (ie, thunder). The main discharge time is very short, about 30 ~ 50μs, the current from thousands of security to hundreds of thousands of security, the wavefront time is only 1 ~ 4μs, the steepness of 7. kA / μs or so.
Pefe Hose,Ptfe Hydraulic Hose,Ptfe Hose R14,Teflon Hose
SHIJIAZHUANG STRONGFLEX I/E CO.,LTD. , https://www.hydraulichosegroups.com