EG1 CH.4 Flashcards
The electrical system is comprised of four main elements, what are they?
Generation, Transmission, Distribution, and Substations
What key characteristic does all electrical systems have in common?
Methods of protection
What are some abnormal conditions that the electrical system checks for?
Excessive current, abnormal voltage (too high or low), deviations in frequency, and low power quality.
Where does the electrical system originate?
The generation station
What range is electricity generated at?
Between 13.8 & 24 kV
What does “the grid” refer to?
The interconnected transmission systems.
What is the common purpose of generation stations?
To generate power as efficiently as possible
What is another form of generation found in the distribution system?
Small-scale generation or dispersed micro-generation
What is the purpose of transmission systems?
The purpose of the Transmission system is to move large quantities of power over long distances.
What are the common transmission voltages?
765 kV, 500 kV, 345 kV, and 230 kV
What does NERC stand for?
The North American Electric Reliability Corporation
What does NERC do?
NERC oversees the nine reliability councils in North America. Eight in USA and one in Canada.
What are the common sub transmission voltages?
44 kV, 69 kV, 115 kV, and 138 kV
When does sub transmission become necessary?
Sub transmission becomes necessary when medium-sized blocks of power need to be delivered to distribution substations at the load center.
What is a load center?
An area where power is being consumed.
Where do sub transmission lines originate from?
Generating facilities or sub transmission substations fed by transmission lines.
What is the range of voltages for the distribution system?
2 - 34.5 kV
What are the common voltages for distribution?
7.2/12.5 kV, 7.6/13.2 kV, 12/20.8 kV, 14.4/24.5 kV, & 19.9/34.5 kV
What are the common service voltages?
120/240 V, 120/208 V, 240/480 V, 480 V, & 277/480 V
Substations have three primary functions what are they?
Change the voltage of circuits from one level to another, connect or disconnect lines or equipment from each other, and control the flow of power by adjusting the voltage and current.
Besides the primary functions, what are some other important functions of a substation?
Regulating current flows and voltage levels, controlling frequency, eliminating lightning and switching surges, metering power use, and connecting communications signals to the circuits.
What is the advantage of AC over DC?
Alternating current can be transformed and direct current cannot.
