How Power Is Delivered To You
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| Electrical power has become almost as much of a necessity as water in our everyday lives. No one really thinks much about it until an outage occurs and it isn't there. It is used
24 hours a day, seven days a week, 52 weeks a year. We use it for heating, cooling, cooking, refrigeration, light, sound, motion, computation and entertainment. Electrical power is a dynamic commodity and must be produced as it is being used. Production of electrical power we use occurs in many power plants across the United States. The majority of these plants burn coal to produce electrical power; however, some are powered by water (hydroelectric), natural gas, oil, nuclear, wind and geothermal. In all cases energy from the fuel source is used to spin an electrical generator producing three-phase AC electrical power. |
| Menard Electric Cooperative has no generation capacity of its own. Electrical power used on the Menard Electric distribution system is purchased from Prairie Power, Inc. (PPI). PPI provides this power from its coal fired generation at the Pearl power plant and natural gas fired combustion turbines at the Alsey generation facility. The remainder
of Cooperative's power needs are purchased from Ameren CIPS. |
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| Prairie Power's Pearl power plant |
Combustion turbine at Prairie Power's
Alsey site |
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| At most power plants electrical power is generated at 12,000 to 15,000 volts. From the generator it is taken to a transmission substation on the plant site where a power transformer is used to step the voltage up to a transmission voltage level somewhere between 69,000 and 765,000 volts. This high voltage electrical power is then transported from the power plant substation to other transmission and distribution substations through the transmission system. These extremely high voltages used on the transmission system allow for a greater amount of power to be transported across the system with less electrical line losses and greater efficiency. These transmission lines are supported by either steel towers or wood poles, primarily dependent upon the level of voltage of the transmission line. |
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| A typical
electrical power grid |
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| A transmission substation |
Steel transmission towers |
| The electrical power is carried by the transmission system to a number of power or distribution substations where the electrical power is stepped down by means of a power transformer to primary distribution voltage levels between 5,000 and 35,000 volts for distribution to individual customers. Menard Electric Cooperative receives its electrical power at a transmission voltage of 69,000 volts at
18 distribution substations located throughout its eight county service area. Menard then distributes the power from the distribution substations across its distribution grid to its members at a three phase primary voltage level of 12,470 volts and a single phase primary voltage level of 7,200 volts. |
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A typical power distribution system
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| A distribution (power) substation |
A three phase distribution line
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| Menard Electric's distribution grid consists of 1,800 miles of single phase, 7,200 volt line and 750 miles of three phase, 12,470 volt line. In order to provide members electrical power at their required service voltages, distribution transformers are installed along the line at each business, residence and farm. Residential services and most farms require 120/240 volt single phase service, which is provided by a single distribution transformer located on the pole or on a concrete pad at the member location. Some farms, larger businesses and the many irrigation services served by the cooperative require three phase services. These three phase services may be 120/240 volts, 120/208 volts or 480 volts. These services are provided by three single phase distribution transformers wired together to form a three phase bank located on the pole adjacent to the service, or by a single three phase transformer located on a concrete pad at the member location. |
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| Single phase
distribution transformer |
Three phase distribution
transformer bank |
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| From the distribution transformer or transformer bank, secondary and/or service conductors are installed to the electrical meter, located either on a metering pole or on the member's house or building. The meter measures all energy used by the member in kilowatt hours (KWH). In the case of three phase services the meter also measures kilowatt (KW) demand which reflects the highest
15 minute requirement for power. This meter is used by the cooperative to determine the member's electrical requirements as well as for billing purposes. From the meter the member or his electrician installs the service entrance conductors which provide power to the main electrical panel within the house or building from which the member's lighting and power loads are served. |
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| A meter pole |
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