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PEXLINK - Line Surge Arresters

PEXLINK is a concept of Line Surge Arresters (LSAs) for minimizing disturbances on overhead lines resulting from unforeseen impulse overvoltages. Based on Hitachi ABB Power Grids' silicone-housed PEXLIM arrester, together with line-hardware and an automatic disconnecting device, the PEXLINK concept offers secure and robust performance to improve line availability and security of electricity supply.

The PEXLINK concept enables a reliable power grid by providing transmission line protection for a disturbance-free system operation up to 800 kV

 

Applications

  • Protection of over-head lines 
  • Lightning overvoltage protection 
  • Switching overvoltage control
  • Increasing line availability and reliability
  • Compact insulation lines
  • Upgrade of transmission lines
  • Extended station protection
  • Substitute for shield wires

Why Hitachi ABB Power Grids?

  • Minimum maintenance cost
  • Customizable mechanical and electrical design
  • Robust installation hardware
  • Easy to install
  • Well-proven PEXLIM surge arresters
  • Automatic disconnecting device
  • Advanced wireless monitoring

Get to know more

Improving the reliability and availability of transmission lines

PEXLINK is Hitachi ABB Power Grids concept for improving transmission line reliability and availability by providing protection of line insulation. In addition to using our well-proven polymer-housed arrester PEXLIM along with additional accessories for fixing the surge arresters across the insulators the PEXLINK concept utilizes a special disconnecting device for automatic disconnection of the arresters in the event of an overload of the arresters. The PEXLINK concept is a simple, cost-effective and proven method of increasing the performance of transmission lines.

The PEXLINK concept has traditionally employed Non-Gapped Line Arresters (NGLA) for protection of transmission lines as such solution offers several important advantages. For the system voltage of 765 kV Hitachi ABB Power Grids is now also able to offer an innovative Externally Gapped Line Arrester (EGLA) solution that provides the user with many unique benefits previously reserved for NGLA solutions only like switching control.

Using Hitachi ABB Power Grids' standard PEXLIM arrester

Hitachi ABB Power Grids' philosophy is to provide protection for line insulation at selected locations. The main element of the PEXLINK concept is the gapless silicone polymer-housed arrester PEXLIM with metal-oxide (MO) active elements. The PEXLIM surge arrester have been used for many years for protection of equipment in sub-stations and their superior protective performances are well-known.

The low weight of the PEXLIM arrester permits installation on existing structures and the polymer housing gives increased reliability of the line equipment as well as safety for people and animals which may be in the vicinity of the lines during overstress conditions

Disconnecting Device

To ensure quick, safe, automatic and controlled disconnection of a failed arrester, Hitachi ABB Power Grids uses a special disconnecting device and a suitable link in the ground circuit of the surge arresters.

PEXLINK Concept Solution

To achieve optimal placement and selection for a PEXLINK installation Hitachi ABB Power Grids provides a service in which we conduct computer simulations of transmission lines to determine optimal installation strategy: e.g. installation locations, tower configuration and  arrester stress level at each of the chosen locations along a transmission line. This approach will ensure that the installation strategy is cost-efficient whilst maximizing the performance improvements.

Transmission line outages – an unacceptable problem in a modern power grid

Both large and small public/private utility owners of transmission systems face a sharpened competitive situation which demands increased availability and reliability of the systems. At the same time consumers have become more demanding as their processes are dependent on constant and reliable energy supply of good quality. Hence, there is a strong demand for a reliable power grid both from the utility owners as well as the electricity consumer perspective.
Increased line availability for lightning events
By locating the PEXLINK on sections of lines with high footing impedance towers and on additional low footing-impedance towers at each end of the section, PEXLINK protects existing shielded and non-shielded lines from abnormal lightning surges (frequent or high amplitudes) and reduces the outages.
The reduced outages are beneficial also indirectly in that sensitive equipment are not damaged and the circuit breakers overhaul interval can be extended. Thus, total maintenance costs are also reduced.
This protection may be used for all system voltages where the stated abnormal conditions exist. Arresters with moderate energy capability are often enough. However, the high-current capability must be large and distribution-type arresters may not be suitable.
Increased line availability for switching events
For long EHV lines, station surge arresters are usually located at line-ends. By deploying PEXLINK at one or more points along the line e.g. at midpoint or 1/3 and 2/3 line length switching surge overvoltages and thus line insulation requirements could be limited without the use of pre-insertion resistors. The surge arresters used for this type of PEXLINK application should be designed for high energy capability. Usually an SL (PEXLIM R) or SM (PEXLIM Q) surge arrester will be enough out on the line but higher arrester classes may be necessary at the receiving end of the line

Non-Gapped Line Arresters (NGLA) for all system voltage levels

The NGLA by Hitachi ABB Power Grids can be used on all voltage levels and increases the availability of electricity networks by providing efficient and reliable protection against disruptions caused by lightning strike and switching overvoltage events.

Hitachi ABB Power Grids NGLA are built using well-proven and robust installation hardware, whilst keeping the installation time and effort to a minimum. The hardware is designed to allow for flexibility of installation

Hitachi ABB Power Grids NGLA design offers a number of benefits:

  • ·Full disconnection with integrated replacement indication – achieves full insulation withstand for the transmission line in case of a fault and provides a visual indication of the need to replace an overloaded NGLA
  • Flexibility of installation – allows for installation on different tower and line configurations
  • Quick and easy installation – outage time of critical transmission lines can be kept to a minimum as the installation process only requires standard tools and most of the build can be prepared in advance at ground level
  • Robust installation hardware – from our experience with PEXLINK NGLA and through extensive testing far beyond the standard requirements, the longevity of the solution with minimal risk of interruption and outages is assured
  • Easy asset replacement management – the universal design of the NGLA enables ease of managing spare stock and performing replacement of failed units
  • Switching control – provides switching control functionality

Externally Gapped Line Arrester (EGLA) 765 kV

The EGLA 765 kV increases the availability of Ultra-High Voltage (UHV) electricity networks by providing efficient and reliable protection against disruptions caused by lightning strike and switching overvoltage events.

Designed for applications at 765 kV, this line surge arrester provides efficient and reliable protection against overvoltages caused by both lightning strikes and switching overvoltages – a unique feature for an EGLA.

The EGLA for 765 kV is built on the vast experience of our PEXLINK concept using well-proven and robust installation hardware, whilst keeping the installation time and effort to a minimum.

Hitachi ABB Power Grids EGLA design for 765 kV offers a number of unique benefits:

  • Full disconnection with integrated replacement indication – achieves full insulation withstand for the transmission line in case of a fault and provides a visual indication of the need to replace an overloaded EGLA
  • No need for specific type testing – independently use of the EGLA on various tower configurations without the need to re-perform type testing
  • Short implementation time – implementation time can be minimized due to absence of specific type testing requirements
  • Quick and easy installation – outage time of critical transmission lines can be kept to a minimum as the installation process only requires standard tools and most of the build can be prepared in advance at ground level
  • Robust installation hardware – from our experience with PEXLINK NGLA and through extensive testing far beyond the standard requirements, the longevity of the solution with minimal risk of interruption and outages is assured
  • Easy asset replacement management – the universal design of the EGLA enables ease of managing spare stock and performing replacement of failed units
  • Switching control – provide switching control functionality in a similar way to NGLA, a unique feature for an EGLA

EXCOUNT-II is our remote wireless monitoring and diagnostics product with the most extensive and powerful features that enables users to keep track of overvoltages in the network as well as providing state-of-the art online condition monitoring of arresters.

The sensor enables advanced surge registration with date and time of surge events along the transmission line - enabling the user to assess the operation of the PEXLINK installation. In addition, the EXCOUNT-II can measure the essential resistive leakage current that gives a good indication of the arrester’s condition and fitness for continued service – an important feature for critical installations.

The measurements can be remotely read when convenient with the aid of a hand-held transceiver and an external antenna. Remote reading provides increased personnel safety compared with conventional counters.

The measured data can then be transferred to a computer for statistical analysis. Included with EXCOUNT-II is specially designed software which facilitates download of the measured data from the transceiver and permits quick analysis and report­ing of the collected information.

The sensor is housed in a sealed, weather-proof case, suitable for outdoor use and proven to match the short-circuit capability of the arrester to which it is connected. The sensor requires no external power supply or battery replacement.