Volts - The practical unit of electromotive force or potential difference. One volt will cause one ampere to flow when impressed across a one ohm resistor. A simple analogy can compare voltage to the pressure of water in a pipe.
Ampere (Amp) - The practical unit of electric current. One ampere is the current caused to flow through a resistance of 1 ohm by 1 volt. Amperage or current can be compared to the amount of water flowing through a pipe (conductor) per unit of time.
Watts - An amount of power, specifically electric power, expressed in watts or kilowatts. The electric power required by an appliance or device.
Watts = Volts X Amps
A simple analogy could equate voltage to the pressure of water in a pipe. Current is similar to the amount of water (charge) flowing per unit time.
Kilowatt - hour (kWh) - The most common unit of measure used to bill for electricity. The kWh measures the total work done. To calculate the energy used, multiply the rate of doing work (watts) by the total time during which the work was done. For example: a 100 watt light bulb operating for 10 hours equals 1 Kilowatt - hour.
One kWh = 1000 Watt hours
Energy - measured in kilowatt hours (kWh).
Demand - measured in kilowatts (kW). The rate at which energy is used, for NPPD retail customers this means the average over a 30 minute time period. If demand is used in the calculation of the bill, the highest demand registered during any 30 minute interval included in the billing period will be used in the calculations.
Utilities must provide electrical power when their customers need it. Electricity cannot be stored as natural gas, propane or coal can be, so the generating plants must be controlled to match the fluctuating demands of the customers being served. At the same time, the transmission and distribution systems must be built to meet each customer's peak demand. This means that the generating capability must be able to match the peak use of the utilities customers, plus regulatory reserves. If the utility cannot generate enough energy at peak time periods, it must buy power on the open market to serve it's customers at a time when the price is at its highest.
Load Factor - The ratio of the average demand to the peak demand over a given time period (daily, monthly, annually). The higher the load factor, the more consistently the customer utilizes energy in the facility.
Load Factor = _______________kWh_________________
Peak demand (kW) x hours in time period
Power Factor - expressed as the ratio of demand to kilovolt amperes or
Power Factor = useful current (the current used to do work )
total current (the total current needed to operate the machine)
Examples: A burner on an electric range or an incandescent light bulb are said to be at 100% power factor because they cause no useless current in the electrical system, where an electric induction motor requires some power to generate the motor's magnetic field, yet does no useful work.
Power Quality - NPPD's goal is to provide a steady source of electrical power, with a predictable, stable voltage; a stable frequency; and a dependable, steady source of maximum current. When variations deviate from these standards it can be referred to as a "power quality" problem. These variations are typically caused by reactive or harmonic currents within a facility.
Examples:
Reactive Current - Induction motors use power to establish and sustain the magnetic field needed for the motor to operate, which is power that is not used to do useful work, but must still be considered in the capacity of the electrical system.
Harmonic Current - Computers, UPS systems, office equipment, PLC's, variable frequency AC drives, DC motor drives, are all examples of contributors to harmonic distortion. These devices draw current at frequencies well above the normal power delivered by the utility (60 hz).
Power Quality is a complex and frequently misunderstood concept that requires the application of sound engineering concepts, by a well trained Power Quality Engineer. For further assistance with your Power Quality issues please contact your Account Manager or call 1-877-ASK-NPPD (275-6773).
Rates - Your rate, or the price you pay for the electricity you use is determined through a cost of service study and approved by the Board of Directors that has been elected by the public. The rates of a public power utility are established to recover the costs of providing electrical service, without building in the profit margin or share holder dividends that must be considered in a private utility. The lower rates and local control are two of the major benefits of public power. Nebraska is the only state in the union that is wholly served by public power.
Summer / Winter Rates - Summer rates apply for use between June 1 and September 30, and reflect the higher costs associated with the increased demands for electricity during this time of the year in Nebraska.
Winter rates apply from October 1 - May 31, and reflect the cost of serving your electrical needs during those months when the peak demand is typically lower than the levels registered during the summer rate period.
Industrial Rates - These rates apply to customers with very large electrical loads and are typically manufacturing facilities. Unlike other categories, the demand is a critial piece of the information used to calculate the monthly bill.
The General Service Demand Rate is designed for large commercial and some industrial customers. A meter that registers electrical demand has been installed on these facilities and the demand is used as a part of the calculation of the monthly bill.
The High Tension Service Rate is designed for large industrial customers. These customers are typically served from a substation dedicated to that customers service requirements. A meter that registers electrical demand has been installed on these facilities and the demand is used as a part of the calculation of the monthly bill.
For more information on the factors that make up your billing, view NPPD's Standard Electric Rates Brochure.
For more information, contact an NPPD representative at 1-877-ASK-NPPD (275-6773).
