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Power = Voltage x Current
Current: The flow of electricity. Standard unit of current is Ampere.
Voltage: Force that pushes electrons through the wire. Standard unit of voltage is Volt.
Amplitude: Size or magnitude of the current.

The electromagnetic current which flows through wires is made up of real and reactive powers.

Real Power: Power created through the synchronized alignment of Amps and Volts within a Current. Real Power is used by computers, lightbulbs and batteries.

Reactive Power: Power created through the asynchronized alignment of Amps and Volts within a Current. Reactive Power is used by washing machines, refrigerators and air conditioning units. This power is important in keeping Voltage levels up to operate transmission lines.

Reactive Power (KVAr) is the difference between Active Power (KW) and Total Power (KVA) consumed by the machine. Reactive power is responsible for generating magnetic fields.

The above diagram illustrates two scenarios with different power factors:
a) represents a larger power factor angle, with more reactive power needed to operate machinery (to push active power through).
b) represents a smaller power factor angle, where less reactive power is needed to operate machinery. The less reactive power needed, the more ideal.

1. Generator
Electricity is generated by power plants. Total electric output has to rise and fall in order to meet the total demands on the electric system.

2. Transmission Station
These act as way stations that link power lines for increased reliability and step up voltage for long distance transmission.

3. Transmission Lines
High-voltage lines are more efficient for transmitting power. Raising the voltage reduces power loss, but much electricity is still lost over long-distance lines.

4. Distribution Substation
Voltage is reduced for distribution to customers, usually to between 12 kilovolts and 35 kilovolts.

5. Distribution Lines
Field transformers step down the power to 120-240 volts (voltage that comes out of the plug in a wall).

6. Housing Units
Electricity reaches and powers units.

When a transmission line disconnects, it puts more load onto the other functioning power lines. This means a need for more reactive power is necessary to keep voltage up across transmission lines. This is made possible by the Protective Relay System.

When there is insufficient reactive power due to an increase in its demand and inadequate reactive power supply, the voltages of the transmission lines drop. The electric system is designed to shut off the lines if any condition threatens the safe operation of these lines, such as extreme highs and lows in voltage. When a fault occurs on the line, the protective relay system is designed to break the circuit. This is known as a line trip.

what is
read moreBLACKOUT 2003

Around 4pm on August 14, 2003, America faced the largest power outage in the nation’s history

How should power flow around the Great Lakes?

A large amount of low-cost electricity flows from transmission lines connecting the Midwest region and the Mid-Atlantic region. Transmission lines carry electricity through long distances, allowing power to flow between these regions.

Power flow in the Ohio region

The blackout began in Ohio. Under normal conditions, power enters Cleveland through transmission lines running through the area, carried from other regions of the United States south of Ohio and around the Great Lakes, particularly from the Midwest.

How did the blackout cascade?

Transmission line in Ohio failed due to brush fire; contact between line conductor and a tree caused damage.

Another transmission line in Ohio failed due to contact with a tree and as the load on other lines increased, subsequent transmission lines in Ohio began .

Transmission lines in Northwestern Ohio tripped, cutting off the transmission paths between Southern and Western Ohio from Northern Ohio and Eastern Michigan.

As more transmission lines disconnected across Michigan and Ohio, power flow between Western and Eastern Michigan was cut off. Cleveland was also cut off from Pennsylvania. There was a large power surge needed to serve loads in Eastern Michigan and Northern Ohio due to increasing disconnected lines.

Further lines tripped as voltages and frequencies on lines changed, causing a blackout cascade. Western Pennsylvania got cut off from New York. Paths were cut off between New Jersey and Northern Ontario due to the system and relay reactions to protect the equipment. This isolated the Northeast. These events left most of the Midwest and Northeast, as well as parts of Ontario without electricity.

Deficiencies in corporate policy on how to react to system failures played a large role in the blackout cascade.

Corporations involved:

FirstEnergy (FE)
Operates a control area in northern Ohio.

American Electric Power (AEP)
Operates a control area in Ohio just south of FE.

Midwest Independent System Operator (MISO)
An ISO. Reliability coordinator for FirstEnergy.

Pennsylvania, Jersey, Maryland (PJM)
An ISO. Reliability coordinator for PJM.

1 Inadequate Awareness of System

FE did not identify and resolve issues in the system. When power lines went out at the beginning stages, they had inadequate information and understanding of the conditions. While more phone calls were being made between electrical groups, FE still struggled to understand earlier problems.

2 Inadequate Diagnostic Support and Equipment

The interconnected grid’s reliability organizations were not able to provide real-time diagnostic support. FE did not have adequate equipment to act upon deviations in the system.

3 Lack of Procedures Between ISOs

Although PJM and MISO share a common boundary, they lacked procedures between themselves and guidelines to coordinate operations. The fragmentation of electricity management requires clear communication between reliability coordinators.

The blackout created a domino-like reaction that left 50 million people across the Northeast and Midwest, and Ontario, Canada, in the dark.

The final blackout area

The populations affected

Power was not restored for 4 days in some parts of the United States and for more than a week in parts of Ontario, Canada.


There is a calculated loss of approximately $6.4 billion.

Consumer and Industry

Spoilage of food products and waste products created.


Traffic lights turned off, pedestrian accidents increased, people were evacuated out of subways.


Airplanes were rerouted to other airports, some flights were canceled.

Electronic Devices

Cell phones stalled by circuit overloads, computers shut down in business and home environments.

Illegal Incidents

Looting occurred, although not to the extent of looting during blackouts in the past.