Defining Energy Transmission Line Design

There a number of considerations that factor into transmission line design. Energy transmission lines have specific parameters that define them. These parameters have implications on the environmental effects. The basic parameters include: 

· Nominal Voltage

· Length of Line

· Altitude Range

· Design Loads 

   The nominal voltage is an approximation to what the actual line voltage would be. Actual voltage varies based on resistance, distance, connecting equipment, and the line’s electrical performance. Altitude range roughly means the expected weather and terrain encountered. Design load is also based on the weather factor. For example the design load that wind and ice put on the energy transmission lines and towers. This affects the tower dimensions, lengths, tower design, and conductor mechanical strength and wind dampening.

Tower Design Parameters

Transmission towers are designed to keep conductors separate from the local surroundings and each other. The higher the energy transmission voltages are the greater the separation distance needs to be. When an arc can jump from the transmission line to the ground causes a fault to ground scenario. This is when there is a transfer of electricity to the surroundings. This can also occur between the conductors. This is referred to a phase-to-phase fault.

        The first design consideration is the distance between the conductors, the tower, and other potential arcing structures. This provides a general idea for the physical dimensions of the tower. This includes the tower height, conductor spacing, and insulator length for mounting.

        Next design consideration is the structural strength of the tower frame to maintain the first design requirements. This takes into account the component, weather, and possible impact loads.

        The final design consideration is to provide the necessary foundation to support the tower and the predetermined design loads.

Clearance Design Parameters

The basic function of the tower is to isolate conductors from the surrounding, other conductors, and potential arcing structures. Clearances based on phase-to-tower, phase-to-phase, and phase-to-ground. Phase-to-tower clearances are typically maintained by insulator strings that must take into account of possible conductor motion. The phase-to-ground clearance is based on the tower height, to minimize line temperature and the potential for line sag, and controlling vegetation and potential arcing structures. Phase-to-phase separation is controlled through tower geometry and limiting line motion.

Designing for Lightning Protection

The taller the tower the higher the chance for a potential lightning strike. Lightning strikes can cause considerable damage to energy transmission and consumer equipment. To minimize lightning strike damage an extra set of cables are run from the top of the tower to the ground for the lightning to follow. These are commonly referred to as shield wires and help ensure that equipment failure is prevented.

Designing for Conductor Motion Suppression

Weathering effects producing conductor motion can potentially cause damage to energy transmission equipment. The most common type of energy transmission damper is the Stockbridge damper. These are installed below the conductors, adjacent from the attachment point on the conductors to the tower. Adequate prediction for weathering effects can help in determining the damper design required for the transmission tower. These prevent the vibrational effects of weathering to potentially cause damage to utility equipment.

E3.Cable for Physical Design Layout

E3.Cable allows for a versatile blend of electrical and mechanical CAD combined into a sophisticated platform. This will provide tools and features that will make designing energy transmission lines, substation interconnections, and transmission towers easy and simple. Provides you with the needed features to keep designs from clashing while maintaining geometric requirements for mechanical structures.

        Allows for the creation of interconnecting system panels and transmission lines with easy drag and drop snap in features. Create an easy error free design based on input parameters based on the user’s demand. Provides some of the following.

· Creates Physical Representation of Panel Controllers

· Design Rule Check

· Clash Detection

· Placement Error Prevention

E3.3D Routing Bridge

E3.3D routing bridge provides an easy transition between the most used MCAD softwares on the market to energy transmission line routing and configuration. Easily transfer MCAD files into the E3.3D routing bridge to determine energy transmission line length and diameter for design parameters. This provides an intermediate step between joining the mechanical and electrical engineering aspects in one easy to use software. E3.3D routing bridge provides a clearer image of interconnections between conductors, energy transmission lines, and insulators and the necessary clearance to achieve operational engineering parameters. It provides the follow features:

· Transferrable Component Information to MCAD

· Check for Component Clash in MCAD

· Accounting for Transmission Sag or Bends

· Calculate Length of Energy Transmission Lines and Segments in MCAD