Underground Transmission Lines
Underground Transmission Lines
These transmission lines can be placed underground.
Transmission lines form the back bone of the electrical network, connecting the
bulk generation with the distribution system. Transmission lines are used to transport large quantities of electricity efficiently. They operate at very high voltages, in order to reduce transmission losses. Traditionally, the transmission lines are overhead. However, there is increasing need for underground transmission lines, particularly in areas where the availability of easements is limited such as urban areas.
The proper selection of the cables, design and installation of the cable system, is important for the secure and reliable operation of the power system. This is especially true for transmission lines, which need to be secure and reliable. Factors to consider are the application, a historical knowledge of the cable, types of cable systems, manufacturing practices and industry standards.
A cable installation system should be designed with knowledge of the cable that has been selected, the intended application and the proper installation techniques for that cable. A cable system designed without regard to the installation methods to be used may not be possible to install. This is particularly important for underground transmission lines.
For example, for underground cable installation, in some cases there can be large differences in pulling tension depending on the
direction of pull that is chosen. If the tension is too large in one direction, using the other direction may have significant impact on the installation sequence and scheduling.
BESST use ETAP software for power system studies and for cable sizing, in addition to in-house technical resources.
bulk generation with the distribution system. Transmission lines are used to transport large quantities of electricity efficiently. They operate at very high voltages, in order to reduce transmission losses. Traditionally, the transmission lines are overhead. However, there is increasing need for underground transmission lines, particularly in areas where the availability of easements is limited such as urban areas.
The proper selection of the cables, design and installation of the cable system, is important for the secure and reliable operation of the power system. This is especially true for transmission lines, which need to be secure and reliable. Factors to consider are the application, a historical knowledge of the cable, types of cable systems, manufacturing practices and industry standards.
A cable installation system should be designed with knowledge of the cable that has been selected, the intended application and the proper installation techniques for that cable. A cable system designed without regard to the installation methods to be used may not be possible to install. This is particularly important for underground transmission lines.
For example, for underground cable installation, in some cases there can be large differences in pulling tension depending on the
direction of pull that is chosen. If the tension is too large in one direction, using the other direction may have significant impact on the installation sequence and scheduling.
BESST use ETAP software for power system studies and for cable sizing, in addition to in-house technical resources.
Items to Consider in Cable Sizing and Installation may include:
- Cable Sizing - based on ampacity, voltage drop and prospective short circuit levels, thermal considerations
- Cable Type – insulation, sheath, jacket, protection
- Cable Accessories – required terminations and joints
- Installation Planning – route selection, construction methods, maintenance requirements, soil conditions, existing
utilities, environmental concerns, permits, licenses, traffic scheduling, cable drum management, off-cuts, copper
theft security
- Cable System Installation – cable support, protection, structures, conduit / duct sizing, raceways, cable tray, trenches,
tunnels, directional boring, type of fill, terminating structures, supervision, testing, typical installation diagrams
- Pulling Installation – pulling machines, power driven pay-out reels, pulling attachments, bend radius, prohibitions,
reels / drum
- Pulling Installation Calculations – pulling parameters / limitations, pulling tension, side wall pressure, jamming conditions
- Installation Accessories – bends, rollers, grips, pulling eyes, pull out sheaves, risers, junction boxes, manholes, vaults,
splicing tents
- Installation Plant & Machinery – low loader trailer, cranes, trenching machines, drum handling, cable cutting facility, GPS
locators
- Cable Type – insulation, sheath, jacket, protection
- Cable Accessories – required terminations and joints
- Installation Planning – route selection, construction methods, maintenance requirements, soil conditions, existing
utilities, environmental concerns, permits, licenses, traffic scheduling, cable drum management, off-cuts, copper
theft security
- Cable System Installation – cable support, protection, structures, conduit / duct sizing, raceways, cable tray, trenches,
tunnels, directional boring, type of fill, terminating structures, supervision, testing, typical installation diagrams
- Pulling Installation – pulling machines, power driven pay-out reels, pulling attachments, bend radius, prohibitions,
reels / drum
- Pulling Installation Calculations – pulling parameters / limitations, pulling tension, side wall pressure, jamming conditions
- Installation Accessories – bends, rollers, grips, pulling eyes, pull out sheaves, risers, junction boxes, manholes, vaults,
splicing tents
- Installation Plant & Machinery – low loader trailer, cranes, trenching machines, drum handling, cable cutting facility, GPS
locators