power systems loss

IMAGES OF VOLTAGE TRANSFORMERS INCLUDING TYPES AN DEFINITIONS Images and Illustration of a typical voltage transformer for medium and high voltage level. A voltage transformer or potential transformer is an instrument transformer intended to have its primary winding connected in shunt with a power supply circuit, the voltage of which is to be measured or controlled. A cascade-type voltage transformer is a single high-voltage line terminal voltage transformer with the primary winding distributed on several cores with the cores electromagnetically coupled by coupling windings and the secondary winding on the core at the neutral end of the highvoltage winding. Each core of this type of transformer is insulated from the other cores and is maintained at a fixed potential with respect to ground and the line-to-ground voltage. A double-secondary voltage transformer is one that has two secondary windings on the same magnetic circuit insulated from each other and the primary. Either or

IMAGES OF CURRENT TRANSFORMERS INCLUDING TYPES AN DEFINITIONS Images and Illustration of a typical current transformer for medium and high voltage level. A current transformer is an instrument transformer intended to have its primary winding connected in series with the conductor carrying the current to be measured or controlled. The ratio of primary to secondary current is roughly inversely proportional to the ratio of primary to secondary turns and is usually arranged to produce either five amperes or one ampere (IEC Standard) in the full tap of the secondary winding when rated current is flowing in the primary. Bar: A bar-type current transformer is one that has a fixed, insulated straight conductor in the form of a bar, rod, or tube that is a single primary turn passing through the magnetic circuit and that is assembled to the secondary, core, and winding. Bushing: A bushing-type current transformer is one that has a round core and a secondary winding insulated from an

load losses: Those losses that are incident to the carrying of a specified load. Load losses include I 2 R loss in the current carrying parts (windings, leads, busbars, bushings), eddy losses in conductors due to eddy currents and circulating currents (if any) in parallel windings or in parallel winding strands, and stray lossinduced by leakage flux in the tank, core clamps, or other structural parts. In equation form:  PLL = I 2 R+PEC+PSL where PLL is the load loss (W) I 2 R is the loss due to current and resistance (W) PEC is the eddy current loss (W) PSL is the stray loss (W). See also: no-load (excitation) losses.

POWER AND DISTRIBUTION TRANSFORMER TERMS DEFINITION 1 accessories: Devices that perform a secondary or minor duty as an adjunct or refinement to the primary or major duty of a unit of equipment. alternating current: A periodic current the average value of which over a period is zero. ambient temperature: The temperature of the medium such as air, water, or earth into which the heat of the equipment is dissipated. ampacity: Current-carrying capacity expressed in amperes, of a wire or cable under stated thermal conditions. autotransformer: A transformer in which at least two windings have a common section.