Rated Voltage：18kV
Nominal Discharge Current：10A
MCOV：15.3kV(rms)
1/4μs Lightning Current：61.5kV(rms)
8120μs Lightning Current Impulse：54kV(Crest)
30/60μs Switching Current Impulse：46.5kV(Crest)
2ms Rectangular Current lmpulse Withstand：250A
4/10us High Current Impulse Withstand：100kA(Crest)
The surge arrester is an overvoltage protector, that is mainly used to protect various electrical equipment (transformers, switches, capacitors, chokes, mutual inductors, generators, motors, power cables, etc.) in power systems, railway electrification systems, and communication systems from damage such as atmospheric overvoltage, operating overvoltage, and power frequency transient overvoltage. It is the basis of insulation coordination of power systems.
A surge arrester is an essential device in electrical power systems designed to protect equipment from over-voltage transients caused by external (lightning) or internal (switching) events. Its primary role is to divert the surge current away from sensitive components, thereby preventing potential damage to the system. Metal-oxide Surge arresters are essential components in power systems, railways, and communication networks.
The working principle of a surge arrester involves its ability to remain inactive during normal voltage conditions and to become highly conductive during over-voltage events. The core component, typically a metal oxide varistor (MOV), has highly non-linear voltage-current characteristics. Under normal conditions, the arrester allows only microampere currents to pass through. However, when the system experiences an over-voltage, the arrester’s resistance drops significantly, allowing it to divert the surge current safely to the ground, thus protecting the equipment.
1、Non-linear Characteristics
Metal-oxide surge arresters utilize zinc oxide as the core material, providing excellent non-linear (volt-ampere) characteristics. This means that under normal operating conditions, the current passing through the arrester is minimal, but it increases significantly during overvoltage events, allowing the arrester to conduct and dissipate the surge energy effectively.
2、High Performance
These arresters have good steep wave response characteristics with no delay for steep wave voltage, low operating residual voltage, and no discharge dispersion. This ensures consistent protection against various types of overvoltage.
3、Structural Durability
They are designed to be small, lightweight, and resistant to collisions, making them easy to transport and install. The special structure with integral molding and no air gap provides excellent sealing performance, making them moisture-proof and explosion-proof.
4、Long Service Life
The unique formula of zinc oxide resistor results in small leakage current and slow aging, extending the service life of the arrester.
Surge arresters are used in various applications to protect electrical equipment such as transformers, switches, capacitors, chokes, mutual inductors, generators, motors, and power cables. Here are some practical applications and case studies:
1、Power Systems
In power transmission and distribution networks, Arresters protect equipment from lightning strikes and switching surges. For example, in a 132kV substation, arresters were installed to protect transformers from frequent lightning strikes, significantly reducing the failure rate and maintenance costs.
2、Railway Electrification Systems
Surge arresters are used in railway systems to protect signaling and communication equipment from transient overvoltages caused by switching operations. In a case study involving a high-speed rail network, the installation of surge arresters improved the reliability of the signaling system and reduced downtime.
3、Industrial Plants
In industrial plants, surge arresters protect sensitive equipment such as PLCs, drives, and control systems from overvoltage transients. An example is a petrochemical plant where surge arresters were installed to protect critical control equipment, resulting in enhanced operational reliability and safety.
A notable application of surge arresters was in a national power grid system where frequent lightning strikes caused significant damage to transformers and other critical components. By installing a metal-oxide surge arrester at key points in the grid, the utility company reported a dramatic reduction in equipment failures and maintenance costs. The surge arrester effectively diverted lightning-induced surges, protecting the infrastructure and ensuring uninterrupted power supply to consumers.
In conclusion, metal-oxide surge arresters play a crucial role in protecting electrical systems from over-voltage transients. Their advanced design, durability, and compliance with international standards make them indispensable in maintaining the reliability and longevity of electrical infrastructure.
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GRL Electric Co., Ltd. is one of the leading companies in the Middle And High End market of low-voltage electric in China
