definition:
Lightning arrester: An electrical appliance used to protect electrical equipment from high transient overvoltage hazards during lightning strikes, and to limit the freewheeling time and often limit the freewheeling value. Lightning arresters are sometimes also called overvoltage protectors and overvoltage limiters.
Scope of application:
AC gapless metal oxide arresters are used to protect the insulation of AC power transmission and transformation equipment from lightning overvoltage and operating overvoltage damage. Suitable for overvoltage protection of transformers, transmission lines, distribution panels, switch cabinets, power metering boxes, vacuum switches, parallel compensation capacitors, rotating electrical machines and semiconductor devices.
Features and principles:
AC gapless metal oxide arresters have excellent nonlinear volt-ampere characteristics, good response characteristics, no freewheeling, large flow capacity, low residual voltage, strong overvoltage suppression ability, resistance to pollution, anti-aging, not subject to altitude constraints, simple structure, no gaps, tight sealing, long life, etc.
Under normal system operating voltage, this arrester exhibits a high resistance state and only microampere current passes through it. Under the action of overvoltage and large current, it exhibits low resistance, thereby limiting the residual voltage at both ends of the arrester.
High voltage arrester
Classification:
There are many types of lightning arresters, including metal oxide arresters, line-type metal oxide arresters, gapless line-type metal oxide arresters, fully insulated composite jacket metal oxide arresters, and detachable arresters.
The main types of arresters include tube arresters, valve arresters and zinc oxide arresters. The main working principles of each type of lightning arrester are different, but their working essence is the same, which is to protect communication cables and communication equipment from damage.
effect:
The lightning arrester is connected between the cable and the earth, usually in parallel with the equipment to be protected. Lightning arresters can effectively protect communication equipment. Once abnormal voltage occurs, the arrester will act to protect. When communication cables or equipment are operating at normal operating voltage, the lightning arrester will not work and is considered an open circuit to the ground. Once high voltage occurs and threatens the insulation of the protected equipment, the arrester will act immediately and direct the high voltage surge current to the earth, thereby limiting the voltage amplitude and protecting the insulation of communication cables and equipment. When the overvoltage disappears, the arrester quickly returns to its original state, allowing the communication line to operate normally.
Therefore, the main function of the arrester is to cut the amplitude of the intruding flow wave through the parallel discharge gap or nonlinear resistor, and reduce the overvoltage value of the protected equipment, thereby protecting communication lines and equipment.
Lightning arresters can be used not only to protect against high voltages generated by lightning, but also to protect against operating high voltages.
The function of a lightning arrester is to protect various electrical equipment in the power system from damage caused by lightning over-voltage of the arrester type, operating over-voltage, and power frequency transient over-voltage impact. The main types of arresters include protection gaps, valve-type arresters and zinc oxide arresters. The protection gap is mainly used to limit atmospheric overvoltage, and is generally used to protect power distribution systems, lines and substation incoming line sections. Valve type arresters and zinc oxide arresters are used for the protection of substations and power plants. In systems of 500KV and below, they are mainly used to limit atmospheric overvoltage. In ultra-high voltage systems, they will also be used to limit internal overvoltage or provide backup protection for internal overvoltage.
Metal oxide arrester
How to choose a lightning arrester:
(1) First fix the base of the arrester, and then install each unit (section) of the arrester group by group from bottom to top.
(2) The arrester has been assembled and tested and qualified before leaving the factory. The on-site installation should be strictly assembled according to the manufacturer's number and cannot be interchanged to avoid changing the characteristics.
(3) Valve arresters with series and parallel cathodes should be selected during installation so that the nonlinear coefficients between the same-phase combination units are close to each other, and the difference should not be greater than 0.04.
(4) The contact surface of the arrester should be wiped clean, the oxide film and paint should be removed, and a layer of electrical compound grease should be applied.
(5) The arrester should be installed vertically, and the sag deviation should not be greater than 2%. If necessary, metal sheets can be placed between the flange surfaces for correction. The three-phase centers should be on the same straight line, the nameplate should be on the same side that is easy to observe, the voltage equalizing ring should be installed horizontally, and finally the gaps should be smoothed with putty and painted.
(6) Tighten the insulator strings to make them tight. The pulling force of each string in the same phase should be balanced to avoid additional pulling force on the arrester.
(7) The discharge counter should be well sealed, reliable in action, and installed in the same three-phase position for easy observation. The grounding is reliable and the counter indication returns to zero.
(8) The exhaust channel of the zinc oxide arrester should be unobstructed. During installation, the gas should be prevented from emitting gas, causing short circuit between phases or flashover to ground, and should not be sprayed into other equipment.
Lightning arrester manufacturer
