Electrical Terms

Know Your Electricity, Save Money on Energy Costs

Brush up on your electrical terminology, because the more you know about electricity, the more money you can save on energy costs.

• Ampere (Amp) - This is the term given to measure the rate at which an electric current flows through the wire at a resistance of 1 ohm when a potential of 1 volt is applied across the resistance.



• Volt - This is the unit of electrical pressure, that potential which will cause a current of 1 ampere to flow through a resistance of 1 ohm.



• Watt - This is a term used to represent a unit of power. It is used to rate appliances, etc. that usually use a relatively small amount of electricity. A watt is equal to 1/1,000 of a kilowatt, or it takes 1,000 watts to equal 1 kilowatt. A light bulb rated at 100 watts is the equivalent to 100/1,000 kilowatts or 1/10 of a kilowatt, meaning this bulb will use electric energy at the rate of 1/10 of a kilowatt-hour per hour. If this bulb is burned steadily for 60 hours, it will have used 6 KWHrs or (60 x 1/10) or (100 x 60) / 1000.



• Ohm - This is a unit of resistance, representing the amount of resistance which will permit 1 ampere to flow at a potential difference of 1 volt.



• KV (Kilovolts) - This term is usually used as opposed to expressing the number of Volts in the thousands. A 138,000 volt line is usually referred to as a "138KV" line as kilovolt is the equivalent of 1,000 Volts.



• KVA (Kilovolt-Amperes) - KVA is the result of the kilovolts being multiplied by the amperes,which is also equal to the kilowatts, i.e., kilowatts = kilovolts x amperes at "Unity" (see Power Factor below). Most line transformers are rated in "kva", such as a "10 kva" transformer.



• KW (Kilowatt) - This term is used to measure the ordinary unit of electric power - it is the rate at which "kilowatt-hours" are delivered or used per hour. If an electric generator has the power capacity of 25,000 kilowatts, this means the generator has the capacity to deliver energy at the maximum rate of "25,000 kilowatt-hours per hour". As "kilo" means 1,000, the kilowatt is the equivalent of 1,000 Watts. It should also be noted that 1 KW is the equivalent of 1.34 horsepower.



• KWHr (Kilowatt-hours) - This term should not be confused with KW above as KWHr is merely a unit of measurement of electric energy transmitted through the electric wires. The KWHr is often compared to the "gallon of water" measurement for measuring your water usage. Although "hour" is included in its name, KWHr is a unit of quantity that really involves no time element, which tends to be misleading.



• Direct Current (DC) - This is the type of current generally found in batteries and is no longer common for home use. As opposed to AC, DC flows continuously in one direction.



• Alternating Current (AC) - This is the type of current found in homes, businesses, etc. AC means the electricity can flow back and forth, reversing in direction. The speed or number of times per second it changes its direction is known as its "frequency". If the change is made at the rate of 60 times a second, it is said to have 60 "cycles" per second.



• House Current - This refers to the common voltage level found in our member's homes. Nearly all houses and buildings are wired for 220/240 Volt service. This voltage is delivered to the member's home after it goes through our transformer. Once in the member's fuse box, the load will be distributed over the individual circuits within the home. Most of those circuits will be at 110/120 Volts, such as for lighting, receptacles, etc.. Some loads, such as electric stoves, window air conditioners, electric furnaces, electric water heaters, etc. require 240 Volt service.



• Horsepower (Hp) - Like the term "kilowatt" defined below, the term "horsepower" also denotes a unit of power. Horsepower indicates the rate at which energy is used or delivered - one horsepower is the equivalent of .746 kilowatts, i.e., a 10 horsepower rating has an equivalent rating of 7.46 kilowatts (10 x .746), meaning that this motor will use 7.46 kilowatt-hours per hour at full load.



• Demand - In electricity, this refers to the amount of kilowatts a particular member or "load" requires. There are several types of demands, such as peak, coincident, non-coincident, off-peak, etc.



• Coincident Demand - refers to the combined demand or load upon the system when it peaks,often referred to as "System Peak". When the system peaks out, everyone's load at that time makes up its coincident demand.



• Non-coincident Demand - is the demand on the system at times other than coincidence or "peak". A customers non-coincidence demand is their demand at a time other than coincidence.



• Peak Demand - is the load a customer puts upon the system at his highest usage or demand for electricity. Peak demand is often used in conjunction with "Coincident" demand, but may also be referred to as his "peak" during any given period. Off-peak Demand is the term used to describe a load's demand on the system at times other than "peak."



• Breaker or Circuit Breaker - This term implies an electrical device located on an electric circuit that can "break" the circuit or open it at that particular location. Breakers are found on the Co-op's lines as well as in the member home, only a substantial difference in sizing and construction differs. The Co-op's breakers are found along the lines or in the substations, and the members' are generally found in the main fuse box or occasionally in sub-fuse boxes that are in-line somewhere along a given circuit. Breakers have the ability to be "reset" and used again. Breakers come in all sizes, depending upon the load and equipment.



• Fuses - are the devices installed on the Co-ops lines when there is a need to be able to isolate a line in the event a fault should appear on the line - we want to be able to isolate it but still keep the rest of the customers not on that particular line in service. The Co-op often uses "fuses" on taps across private right of way or up a long lane to a few customers. Fuses in the home are found in many older homes, usually in the "fuse box" itself, and are activated when a fault appears on a circuit in the home. All fuses are good for one time only. Once blown, they must be replaced with a new fuse. Fuses come in all different sizes, depending upon the rating of the load and the equipment.



• Load Factor (LF) - the month's load on a system as compared to its maximum or peak load for that same period. When a customer creates his maximum demand on the system, he will probably not continue to use electricity at that same level for the whole month, but will use it at different levels throughout the month. The extent of his use for the month as compared to his maximum use for that same month is called his "load factor". Load Factor is computed by dividing his KWHr usage for the month by the product of the month's "peak" or maximum demand for him times the hours for the same period (730 for a month and 8,760 for a year). Shown more algebraically: Load Factor = Month's KWHr Usage / (Peak Demand or KW x 730 or 8,760).



• Power Factor (PF) - used to express the relationship between "useless current" and "useful power". Some devices, especially induction motors as commonly used today, are not being used at capacity and result in a demand on the system greater than that actually being used or put to good use. The actual work being done by the motor results in a certain kilowatt (kw) demand that is measured by the ordinary meters for measuring such demands. This motor, however, when "partially" loaded, makes an additional demand on the electrical system which is not measured by the ordinary meter, but such additional demand requires capacity in the electrical system just the same as the useful demand requires capacity. When there is no useless current in evidence, the power factor is said to be in "Unity".
  
  Power Factor is normally used in calculating kilowatts by the expression KW = KVA x PF. To compute power factor, the expression would be: PF = KW/KVA or (W/(E x I)). If an electric motor requires 100 kilowatts of useful power and is operating at 50% power factor, the above formula would yield as follows: 100 kw = kva x .50 pf. To solve for KVA, kva =100 / .5 = 200.
  
  In other words, this motor requires 200 kilovolt-amperes (kva) of capacity in the electric system although it only uses 100 kw of useful power. The electrical system is still having to provide 200 units of capacity in transformers, lines, etc. to serve that motor. If power factor for that motor could be increased to "unity", the motor would do no more useful work, it would take no more energy to perform this work, but would make a demand of 100 kw on the electrical system, and only 100 kw in capacity in the electric system would be required to serve the motor. If that same 100 kw motor is now working at 70% power factor, the KVA required would be 143, or 100 / .7. An improvement over the 200 previously required. The higher the power factor of a load, the better it is to serve.



• Power Factor Optimization - Depending upon the rate structure of your electric utility, you may be able to save a substantial amount of money on your electric bill. Pay-back period for an equipment purchase including installation cost may be six months up to three years. Utility rate structures that account for reactive power consumption, by either a KVA or var demand usage, or a power factor penalty are the ones that can provide this pay-back. Other ancillary benefits to be gained by optimizing power factor are: lower energy losses, better voltage regulation and released system capacity.



• Electromagnetic Induction - is the basis of operation for electrical generators, induction motors, and transformers. Inductive motors create electromagnetic electricity which creates an electromagnetic field (EMF).