Gas-filled surge arresters operate on the gas-physical principle of the highly effective arc discharge. Electrically, surge arresters act as voltage-dependent switches. As soon as the voltage applied to the arrester exceeds the spark-over voltage, an arc is formed in the hermetically sealed discharge region within nanoseconds. The high surge current handling capability and the arc voltage, which is almost independend of the current, short-circuit the overvoltage. When the discharge has died down, the arrester extinguishes and the internal resistance immediately returns to values of several 100 MΩ.

The surge arrester thus meets almost perfectly all requirements made on a protective element. It reliably limits the overvoltage to permissible values, and – under normal operating conditions – the high insulation resistance and the low capacitance contribute to the fact that an arrester has virtually no impact on the system to be protected.

The capability of the surge arrester in energy dissipation against switching surge is well expressed by the magnitude of kJ/kV (arrester rated voltage). These values show the dissipated total energy per two shots of switching surge that the surge arresters can withstand thermally with these values. Where the energy capability is inadequate in our standard series.

Typical structure of surge arresters are shown in Figure below .The surge arresters are basically composed of the TNR elements, housing and associated parts with insulating gas filling as shown in figures. The hermetic sealing of the housing is constructed with weather-proof synthetic rubber. The pressure relief diaphragm is structured with special metal plate, which is ruptured when a sudden pressure rise occurs in case of the internal failure.

Surge Arresters conduct lightning surges around the protected insulator so that a lightning flashover is not created. They are designed to be installed functionally in parallel with the line insulator. The arrester conducts the lightning surges around the protected insulator so that a subsequent 60 Hz fault on the circuit is not created. The arrester becomes a low ohmic path for the surge as voltage across it increases. When the voltage returns to normal, the arrester once again returns to a high ohmic device with only microamps of leakage current.

If an arrester experiences a surge higher than it is capable of handling without failure, and it is failure, equipped with an isolating device, it will isolating device, disconnect during the event.

After the surge is over, and fault current starts to flow, the disconnector senses the fault and ignites the powder built into the device.

The disconnecting device is not an interrupter so during this rare event, an interrupting device must clear the circuit.

The valve arrester consists of disks of zinc oxide material that exhibit low resistance at high voltage and high resistance at low voltage. By selecting an appropriate configuration of disk material, the arrester will conduct a low current of a few milliamperes at normal system voltage. During conditions of lightning or switching surge over voltage, the surge current is limited by the circuit; and for the magnitudes of current that can be delivered to the arrester location, the resulting voltage will be limited to controlled values, and to safe levels as well, when insulation levels of equipment are coordinated with the surge arrester protective characteristics.

A typical surge arrester consists of disks of zinc oxide material sized in cross-sectional area to provide desired energy discharge capability, and in axial length proportional to the voltage capability. The disks are then placed in porcelain enclosures to provide physical support and heat removal, and sealed for isolation from contamination in the electrical environment.

Telephone / fax / modem protection

Telephones, faxes and modems are equipped with sophisticated but sensitive electronics. Typical circuits used to protect them with surge arresters are shown in following Fig.

These arresters protect against common-mode interference voltages, i.e. surge voltages that appear in both lines to ground. In the event of an over voltage, the arrester protects both exchange lines by conducting the surge current away to ground.

A transmission line arrester also known as a transmission line surge arrester is any arrester that is applied out on the transmission line to reduce the possibility.

The resulting wave when an electrical variation in a circuit such as a transmission line takes the form of translation of energy along a conductor, such energy being always equally divided between current and potential forms. The traveling waves propagate at close to the speed of light and can generate surges at 2-4 times the initial impulse under certain circumstances.

Impulse protective levels of an arrester:

a) Fast front protective level: The highest of either the steep current residual voltage or the front-of-wave impulse spark over voltage.

b) Standard lightning impulse protective level: The highest of the residual voltage at nominal current or 1,2/50 lighting impulse spark over voltage.

c) Switching impulse protective level: The highest of either the maximum residual voltage for the specified switching current or the specified switching impulse spark over voltage.

Application range:

Peace project(police),telecom "global E-eye"(telecom),road monitoring(police), Community Monitoring(building management), monitoring of environment(environment protection),expressway monitoring, etc.

System specification:

The lightning protection of monitoring system of CCTV is relatively complicated firstly we should understand the main reason why the monitoring system was damaged by the lightning and the possible lightning invaded route, specially, the outdoor monotoring equipment suffer from serious damage of lightning. only analysis on basis of the reason of damage, research and discussion on the laying, shield and earthing mode of signal and power line, the lightning protection device of monitoring system device can be selected and used accurately.

The TV monitoring systemis consisting of three parts as below:

1,The former part: composed of monochrome (colour television) vidicon, len, holder, hood , bracket, etc.

2, transmission part:coaxial-cable,wire,Multi-core wire,fibre,which transmiss video,audio or control signal by way of overhead in air,burial under ground or wall following laying.

3, computer roomterminal part: composed of matrix, monitoring device, hard disk video recorder,etc.

A correctly selected arrester can diver surges almost endlessly ,provided the energy to be dissipated is within the capability of the arrester .In the event that an arrester is required to dissipate more energy than it is capable of, it will sacrifice itself by failing short circuit. Most commonly, arrester are connected phase – to – ground and the resultant earth fault will immediately collapse the voltage on that phase, thereby protecting other equipment an the same phase, The upstream protection will initiate a breaker trip to clear the fault, and the failed arrester can then be replaced.

Surge Arrester housing have traditionally been made of porcelain .However , today there is a stronge Arrester housing have traditionally been made of porcelain .However , today there is a strong trend ,and often even a preference ,towards the use of silicone insulators for arrester at all system voltage. There are a number of reasons why silicone is seen as an attractive alternative to porcelain, including potentially better short-circuit capability with increased safety for other equipment and personnel if correctly designed.

The principal "active" element of the Surge Arrester is a metal oxide varistor characterized by high non-linearity. At a working voltage mainly a capacity current flows smaller than 1 mA. Any voltage increase causes a large increase of current flowing through the varistor, leading in turn to immediate limitation of further voltage increase on arrester terminals. When the over voltage disappears, the arrester immediately returns to its basic state.

Surge Arresters are equipped with a disconnecting device that disconnects the arrester from the network if it becomes damaged as the result of over voltage of too high energy or inadmissible voltage increase in the system. If such a situation occurs then the bottom terminal of the disconnecting device is "rejected" by the spring inside. This terminal remains suspended on an insulation "leash".

Kingtronics sell 2-Electrode arresters and 3-Electrode arresters. Following are 2-Electrode arresters and 3-Electrode arresters’s pictures.

Lightning Arresters are protective devices for limiting surge voltages due to lightning strikes or equipment faults or other events, to prevent damage to equipment and disruption of service. Also called surge arresters.

Lightning Arresters are installed on many different pieces of equipment such as power poles and towers, power transformers, circuit breakers, bus structures, and steel superstructures in substations.

Lightning arrester on distribution pole transformer:

Contact us

Tel: (86) 769 8118 8110
Tel: (852) 8106 7033
Fax: (852) 8106 7099
E-mail: info@kingtronics.com
Skype: kingtronics.sales
MSN: kingtronics-sales@hotmail.com
Web: www.Kingtronics.com
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About

Kingtronics International Company was established in 1995 located in Dongguan City of China to handle all sales & marketing for factories located in Chengdu, Sichuan and Zhaoqing, Guangdong, China. In 1990, we established the first factory to produce trimming potentiometer and in 1999 we built up new factory in Zhao Qing, Guangdong. Now with around 850 workers, Kingtronics produce trimming potentiometers, dipped tantalum capacitors, multilayer ceramic capacitors, and diode & bridge rectifier. We sell good quality under our brand Kingtronics, and Kt, King, Kingtronics are our three trademarks. All our products are RoHS compliant, and our bridge rectifier have UL approval. Please visit our Products page, you could please download all our PDF datasheet and find cross reference for our Trimming Potentiometer and capacitors.

Tantalum and Ceramic Capacitors Cross Reference ↓ Download
Diodes & Rectifiers List(PDF: 97KB) ↓ Download
Trimming Potentiometer Cross Reference ↓Download

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