EG1 CH.8 Flashcards
What is the transmission system similar too?
The interconnected highways
T or F: Transmission lines can be local or travel cross country
True
What is a tell tale sign you are looking at a transmission line?
Large tall structures
On average how far apart are transmission towers?
1000 feet
What metal is used for transmission lines?
Aluminum
What is the main objective of transmission lines?
deliver power with a minimal loss
How often is power bought and/or sold?
daily
What determines the amount of power on transmission lines?
Depends on scheduled and emergency deliveries.
What types of current can transmission lines be?
AC or DC
What type of current is most transmission lines?
AC
When would DC be used instead of AC for transmission lines?
When large amounts of power is needed far away and is profitable for the utility.
What are some considerations when determining transmission structures?
Voltage of line, right of way size, geographical terrain, weather, and size of conductor
What is the max voltage for wooden transmission structures?
345 kV
Why do wooden structures have a max voltage?
Limited by pole sizes available
What are some advantages of tubular steel poles compared to wooden poles?
aesthetically pleasing and longer life span
What is the preferred structure type for voltages over 345 kV?
Lattice type towers
What must the insulators do?
They must insulate the line and support the weight of the conductors
What so suspension insulators do?
They are used to support the full line tension in a dead end or to support the span weight
T of F: A dead end insulator would typically have a lower rating then an insulator in a suspension setup.
False, the rating would be higher
T or F: Transmission lines use steel lines for support.
True
When would you see bundled conductors?
When transmission lines deliver extra high voltages
What is a bundle conductor?
A bundle conductor is when there are more than one conductor in one phase
Why bundle a conductor?
reduce radio noise and corona loss
What is corona loss?
refers to the phenomena in which the air ionizes around high voltage lines. Corona loss is audible and visible at night.
What is used to protect transmission lines from lightnin?
Shielding or static wire
What is shielding and static wire?
Lightning protection in the form of small conductors, attached to the top of transmission structures. Either one or two.
Besides lightning protection what other purpose do shielding wires do?
Communication, as they are also built with fiber optics inside them
T or F: A company needs to obtain legal rights to construct and maintain lines.
True
How long can it take to secure right-of-ways to build major transmission lines?
3-5 years
Why are right-of-ways difficult to obtain?
Objections of property owners
The use of the land underneath transmission lines is very restricted. What is usually not allowed?
Buildings
Transmission right-of-ways has to be wider than what?
The entire transmission structure
Transmission insulators can be constructed from several different materials but generally have only two different shapes. What are they?
Suspension and line post
What is the max specs of a transmission conductor?
1-3/4” dia and weight 2.5 lbs per foot
