What are the types of lightning arresters used in the power system?
In order to prevent safety accidents caused by internal and external overvoltage in the power system, overvoltage protection devices such as lightning arresters, lightning rods, and grounding grids are usually installed in substations. As one of the important lightning protection devices, lightning arrester is very common in the protection of substations. Today, Junhe Electronics will share with you the types of lightning arresters used in substations.
Firstly, the function of lightning arresters
Lightning arrester is a protective device that limits overvoltage. It can release lightning or also release the energy of overvoltage during power system operation, protect electrical equipment from the harm of instantaneous overvoltage, and cut off continuous current to prevent system grounding short circuit.
In the power system, lightning arresters are installed in parallel within the system. When the overvoltage value reaches the specified operating voltage, the lightning arrester immediately acts, flows current, limits the amplitude of overvoltage, and protects the equipment; After the voltage is normal, the lightning arrester quickly returns to its original state to ensure normal power supply to the system.
Secondly, the types of lightning arresters in the power system
1. Tubular lightning arrester
A tubular lightning arrester is a protective gap with high arc extinguishing ability. When a lightning strike occurs, both the inner and outer gaps are broken down, and lightning flows through the gaps into the ground. Its structure is relatively complex and is commonly used on 10kV distribution lines as lightning protection for electrical equipment such as transformers, switches, capacitors, and cable heads. Suitable for rural or mountainous areas with small capacity, long lines, low short-circuit current, and strong and frequent lightning activity in power frequency power grids.
2. Valve type lightning arrester
Valve type lightning arresters are applied in power systems. When overvoltage occurs in the system and the peak value exceeds the gap discharge voltage, the gap is broken down, and the impulse current flows into the ground through the valve plate. Due to the nonlinear characteristics of the valve plate, the pressure drop (residual pressure) generated on the valve plate will be limited, making it lower than the impulse withstand voltage of the protected equipment, thus protecting the equipment.
The structure of valve type lightning arrester is complex and is commonly used for lightning protection of 3-550kV electrical lines, transformer and distribution equipment, motors, switches, etc. Suitable for AC/DC power grids, not limited by capacity, line length, or short-circuit current, it can be used in industrial systems for substation equipment and lines.
3. Zinc oxide lightning arrester
Zinc oxide lightning arresters are widely used in power systems. It mainly consists of main components, insulation base, wiring cover plate, and equalizing ring. The main components are assembled by stacking nonlinear metal oxide resistors and sealed in a high-voltage insulation sleeve without any discharge gaps.
Zinc oxide lightning arrester has no discharge delay. After external lightning overvoltage action, there is no power frequency continuation current, and it can withstand multiple lightning strikes. The residual voltage is low, the flow rate is large, the volume is small, the weight is light, and the operation and maintenance are simple. It is commonly used for lightning protection and overvoltage protection of 0.25-550kV electrical systems and equipment.
