Electrical Engineering Basics

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Questions and Answers

Which of the following components is NOT part of a simple large-scale power system?

Generation source

Transmission system

Load or demand

Advanced monitoring equipment (correct)

What is the primary function of a transformer sub-station in a power system?

To distribute power directly to households

To increase voltage for long-distance transmission

To generate power at a high voltage

To reduce high voltages from transmission lines to intermediate voltages (correct)

How is power primarily defined in an electrical context?

The instantaneous rate of consumption of energy (correct)

The voltage level at which electricity is transmitted

The ability to store energy for future use

The total energy consumed over time

What unit is used to measure energy derived from power over time?

Kilowatt-hour Signup and view all the answers

Which factor contributes to complications in the transmission system?

Presence of inductance and capacitance Signup and view all the answers

In electrical formulas, how is power calculated for direct current (dc)?

Power = voltage x current Signup and view all the answers

What is a significant limitation of a simple power system?

It will fail if any single component malfunctions Signup and view all the answers

What is the main purpose of transformers in power systems?

To increase or decrease voltage levels Signup and view all the answers

What is one reason why high voltages are used in transmission lines?

To reduce energy loss through heating Signup and view all the answers

Which voltage levels are typically output from transformer sub-stations for local distribution?

66 kV or 33 kV Signup and view all the answers

What are the cooling mechanisms commonly used in transformers?

Cooling fins and fans Signup and view all the answers

What is the primary function of circuit breakers in a power system?

To stop current flow during faults Signup and view all the answers

What is the consequence of having low resistance in busses with large cross-sections?

Lower energy losses Signup and view all the answers

What is the purpose of capacitor banks in power systems?

To smooth out voltage fluctuations Signup and view all the answers

Why must transmission lines be kept away from the ground?

To prevent electrical arcing Signup and view all the answers

What was one of the primary functions of the transformer invented in 1885?

To step up or step down voltage levels. Signup and view all the answers

What happens when current is reduced in a transmission line at high voltage?

Power loss due to heating is reduced Signup and view all the answers

Which power generation method was first demonstrated by Tesla in the late 1880s?

AC induction motor operation. Signup and view all the answers

What was a major outcome of the Public Utilities Regulatory Policies Act (PURPA) enacted in 1978?

Utilities were required to purchase power from independent generators. Signup and view all the answers

Why were electric utilities regarded as 'natural monopolies' in the early 1900s?

Consolidation resulted in the cheapest production due to economies of scale. Signup and view all the answers

What did the National Energy Policy Act of 1992 aim to achieve in the electricity market?

Establish competitive access to transmission lines. Signup and view all the answers

What was a significant technological advancement for electricity transmission that occurred in 1893?

Establishment of the first three-phase transmission line. Signup and view all the answers

Which of the following is NOT a component of power generation systems?

Chemical reactors. Signup and view all the answers

What was a key challenge faced by the electricity sector in the 1970s?

High fossil fuel prices and inflation. Signup and view all the answers

Study Notes

Turbines

Difficult to replace
Often have a spare kept on hand

Busses

Uninsulated electrical conductors
Large cross-section allows for low resistance
Must be kept far from the ground and other components to avoid arcing

Switches & Switchyards

Used to redirect electrical power

Transformers

Change the voltage of electricity
Increasing voltage is called “stepping up”
Decreasing voltage is called “stepping down”
Often run hot and need to be cooled
Prone to exploding, due to the oil inside
Utilize cooling fins, fans, and blast walls

Circuit Breakers

Stop the flow of current if too much flows, preventing a short circuit or excess demand

Capacitor Banks

Smooth out spikes or “glitches” in the voltage of electrical lines

Transmission Lines & the “Grid”

High voltages reduce the energy wasted as heat in the wires, which reduces the power loss
Transformers cannot add energy, so increasing voltage reduces current, which reduces power loss

Transformer Substations

Reduce high transmission line voltages ( >100 kV ) to intermediate voltages needed for towns or sections of cities ( typically 66 kV or 33 kV)

Smaller Power Transformers

Reduce voltage further to the 240 V delivered to homes

Components of a Power System

Generation - Source of power, ideally with a specified voltage and frequency
Load - Consumes power, ideally with a constant resistive value
Transmission System - Transmits power, ideally as a perfect conductor
Distribution System - Local reticulation of power
Control equipment - Coordinates supply with load

Complications

No ideal voltage sources exist
Loads are seldom constant and are rarely only resistive
Transmission systems encounter resistance, inductance, capacitance, and flow limitations
Simple systems lack redundancy, meaning a failure in a single component can cause the entire system to fail

Power

The instantaneous rate of consumption of energy, or how hard something is working
Power = Voltage x Current (DC)
Power Units:
- Watts (W)
- Kilowatts (kW)
- Megawatts (MW)
- Gigawatts (GW)
U.S. installed generation capacity is around 1,000 GW
Maximum load in Austin is around 2,500 MW
Maximum load for UT campus is around 50 MW

Energy

The integration of power over time, or how much work is accomplished over time
Units used:
- Joule (J)
- Kilowatthour (kWh)
- British Thermal Unit (Btu)

Brief History of Electric Power

Early 1880s - Edison introduced the Pearl Street DC system in Manhattan
1884 - Sprague produced a practical DC motor
1885 - The transformer was invented
Mid 1880s - Westinghouse/Tesla introduced the AC system
Late 1880s - Tesla invented the AC induction motor
1893 - The first 3-phase transmission line operated at 2.3 kV
1896 - AC lines delivered electricity from hydroelectric generation at Niagara Falls to Buffalo
Early 1900s - Private utilities supplied all customers in an area, considered a “natural monopoly”

History, cont’d

By the 1920s - Large interstate holding companies controlled most electricity systems
1935 - Congress passed the Public Utility Holding Company Act
1935/6 - The Rural Electrification Act brought electricity to rural areas
1930s - Electric utilities were established as vertical monopolies
1970s - Inflation, stagnation of demand growth, rising fossil fuel prices, calls for conservation, and growing environmental concerns led to increased prices and calls for industry changes
1978 - The Public Utilities Regulatory Policies Act (PURPA) was passed, mandating utilities to purchase power from independent generators
1992 - The National Energy Policy Act opened the industry to competition, mandating “nondiscriminatory” access to the high voltage transmission, attempting to create true competition in generation

History, cont’d – 1990’s & 2000’s

1996 and 1999 - Texas followed suit with similar legislation

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Description

Test your knowledge on key concepts in electrical engineering, covering topics such as turbines, transformers, switches, and circuit breakers. This quiz will assess your understanding of how electrical systems function and the components involved in power transmission.