Electrical Power Systems in Home Businesses and Factories
For our homes, for our factories, for our businesses and office buildings, electrical power is the lifeblood that keeps our society going. Electrical power systems directly provide jobs for thousands of people and indirectly enable the rest of us to work and live in relative comfort. All modern factories depend on electricity for everything from lighting to manufacturing processes and communication.
In the United States electric power comes from several sources. One thing these sources have in common is that they change some form of energy into electricity. This might be a hydro-electric dam converting flowing water into electricity; a nuclear power generator; a wind farm or most likely a coal-fired or natural gas fired generator. There are some other methods such as solar but they are still a very small portion of the supply system.
The output of a power generating plant is not used directly. It goes out to the power grid through transformers that increase the voltage to as much as 500,000 volts for long distance transmission. High voltage allows the use of smaller wires because as the voltage increases, the current flow decreases; making long distance transmission more efficient.
Substations and Electrical Power Systems
Substations are the next part of electrical power systems. In substations, the high voltage is reduced to several lower voltages and distributed to local power companies. There are three types of substations commonly used. They can range in size from a small fenced enclosure with a transformer and a switch to several acres of equipment. The substations we frequently see in urban neighborhoods are distribution substations. Here is where the power is distributed to the customers. Substations often house the measuring devices to monitor usage so the supplier can charge the local power system for the power used. Transmission substations are connected directly to the power generation plants via the high voltage transmission lines. They take the power and reduce the voltage to be sent to local substations. They can also connect transmission lines via sets of special switches. They usually are large sites with transformers, capacitors to control power flow.
New Energy and Electrical Power Systems
As solar and wind power generation become more common we are seeing collector substations. These connect a number of individual generators (wind or solar) into one connection to the overall electrical power systems. The most common output voltage for collectors is 35kV.
From the local utility company’s substations the electricity is delivered to customers. This can be in voltages ranging from a few thousand (typically 2.4kV or 7.2kV) up to 33kV depending on the customers’ needs. At our homes, this voltage is reduced by pole-mounted or underground transformers to the 240V we’re familiar with. Industrial customers sometimes use the 33kV directly; using their own transformers to manage required voltages. Most commonly industrial and commercial customers use 480V three-phase power.
We take electrical power systems for granted until a power outage, then we blame the power company. In most cases the power company is not the culprit – nature is the biggest threat to our power.
