July 4, 2011

Electrical Engineering Terms - T

  • T&D - Transmission and Distribution.
  • T-Body - A device used to terminate main feeder cables operating at medium voltages (4-35KV nominal). T-Bodies are molded from synthetic rubber and are electrically shielded. They are frequently stacked for multiple terminations and are rated at 600 Amps and are
  • T101 - Term used for IEC 60870-5-101 protocol.
  • Tag Line - A rope used to control the position of equipment being lifted. This is not to be confused with the rope used to actually lift the equipment.
  • Tap Changer - A mechanism usually fitted to the primary winding of a transformer, to alter the turns ratio of the transformer by small discrete amounts over a defined range.
  • TC57 - Technical Committee 57 working for the IEC and responsible for producing standards in the field of protection (e.g. IEC 61850)
  • TCP/IP - Transmission Control Protocol/Internet Protocol. TCP/IP is the method by which data is sent across the internet. These two protocols were developed by the U.S. military to allow computers to talk to each other over long distance networks
  • Temper - The softness of a metal; terms such as soft-drawn, dead soft, annealed, and semi-annealed are used to describe tempers used for conductor metals.
  • Temperature Rise - The increase in temperature that results when electrical load is carried by electrical equipment.
  • Tensile Strength - The greatest longitudinal force that a substance can bear without tearing apart or rupturing; also called ultimate tensile strength.
  • Tension - The force in pounds of kilograms on a conductor installed overhead. Too much tension on an overhead line can contribute to mechanical failure.
  • Termination - 1) The act of preparing the connection or transition of an insulating cable. 2) The device that transitions an underground cable to an overhead cable or wire.
  • Terminator - A device used to transition between overhead and underground, medium and high voltage conductors.
  • TF - The Transfer Function of a device usually an element of a control system.
  • TFE - A Heat-resistant insulation compound made with tetrafluoroethylene (Teflon).
  • Thermal Expansion - The expansion of a material when subjected to heat.
  • Thermoplastic - A plastic compound that will soften and melt with sufficient heat. Thermoplastic insulation compounds are used to manufacture certain types of electrical cables.
  • Thermoset - A plastic compound that will not remelt. Thermoset insulation compounds are used to manufacture certain types of cables.
  • THHN - A thermoplastic-insulated, nylon-jacketed conductor designed for use in dry locations and an operating temperature of up to 90 degrees Celsius
  • Thin Film - See "Amorphous Semiconductor"
  • Thin Film (Photovoltaic) - A layer of semiconductor material, such as copper indium diselenide, cadmium telluride, gallium arsenide, or amorphous silicon, a few microns or less in thickness, used to make photovoltaic cells.
  • Three Phase - Three-phase refers to one circuit consisting of three conductors where the current and voltage in each conductor (phase) is 120° out of phase with each other phase.
  • Three Wire - See Delta.
  • Three-Phase - Multiple phase power supply or load that uses at least three wires where a different voltage phase from a common generator is carried between each pair of wires. The voltage level may be identical but the voltages will vary in phase relationship to each o
  • Through Fault Current - The current flowing through a protected zone to a fault beyond that zone.
  • Throughput - A general term used when defining the rate of data transfer over a particular medium, such as a wireless network or a phone line.
  • Thumper - A high voltage device used to locate an underground cable fault. The device applies a high voltage to the faulted cable with a resulting discharge to ground at the location of the fault.
  • THW - A thermoplastic insulated, moisture resistant conductor designed for use in wet or dry locations and an operating temperature of up to 75 degrees Celsius.
  • THWN-2 - A thermoplastic insulated, nylon-jacketed, moisture resistant conductor designed for use in wet or dry locations and an operating temperature of up to 75 degrees Celsius.
  • Tie - A wire device that connects a conductor to an insulator. Factory formed ties are manufactured by Preformed Line Products Company.
  • Time Delay - A delay intentionally introduced into the operation of a relay system.
  • Time Delay Relay - A relay having an intentional delaying device.
  • Tow Axis Tracking (Photovoltaic) - A photovoltaic system capable rotating on two axes (vertical and horizontal) to track the sun for maximum efficiency of the solar array.
  • TPI - Tap Position Indicator for transformers.
  • Tracking Array (Photovoltaic) - A photovoltaic array that follows the path of the sun to maximize the solar incident on the photovoltaic surface. The two most common orientations are (1) One axis tracking where the array tracks the sun east to west and (2) Two axis tracking where the a
  • Transco - A for profit Power Transmission Company.
  • Transducer - A device for converting an electrical signal into a usable direct current or voltage for measurement purposes.
  • Transducer Error - The actual value of the output minus the intended value of the output expressed algebraically.
  • Transducer Factor - The product of the current transformer ratio (CTR) and the voltage transformer ratio (VTR). Also called the power ratio.
  • Transducer with Live Zero - A transducer which gives a predetermined output other than zero when the measurand is zero.
  • Transducer with Suppressed Zero - A transducer whose output is zero when the measurand is less than a certain value.
  • Transformer - An electro-magnetic device used to change the voltage in an alternating current electrical circuit.
  • Transformer Bank - See "Bank".
  • Transformer Insulation - This is the material that is used to provide electrical insulation between transformer windings at different voltage levels and also between the energized parts and the metal tank of the transformer. Generally, for large transformers used in power applica
  • Transformer Ratio - When used in reference to Instrument Transformers, this is simply the ratio of transformation of one or more transformers used in the circuit. If both Cts and VTs are included, the transformer ratio is the product of the CT and the VT. For example, assume
  • Transformer Voltage Regulators - Mechanisms that use multiple voltage taps on a transformer-like device to adjust voltage on a power line. As the voltage increases or decreases on the circuit, sensors in the voltage regulator call for the input or output of the regulator to connect to di
  • Transient - See "Voltage Transient"
  • Transmission System - Normally, the highest voltage network of an electric utility system. This is the portion of the system that carries high power over the longest distances. Typically operating at voltages in excess of 100 kV, and most usually at 200 kV and above.
  • Traveler - See "Stringing Block".
  • Tree Wire - A type of Overhead Distribution Wire that is insulated for momentary contact with tree branches and used as a primary voltage conductor.
  • Treeing - Water treeing is a form of cable insulation degradation where micochannels, that often appear as a tree-like structure in the insulation, develop due to a complex interaction of water, electrical stress, impurities and imperfections. The tree-like channe
  • Trickle Charge (Battery) - A continuous low rate charge that compensates for the self discharge rate of a battery. Also known as Float Charge.
  • True RMS Amps - 1) The effective value of an AC signal. For an amp signal, true RMS is a precise method of stating the amp value regardless of waveform distortion. 2) An AC measurement which is equal in power transfer capability to a corresponding DC current.
  • True RMS volts - 1) The effective value of an AC voltage value regardless of the waveform distortion. 2) An AC measurement which is equal power transfer capability to a corresponding DC voltage.
  • TRXLP - Tree Retardant Cross Linked Polyethylene. A thermoset plastic compound that is used for insulation of wire and cable containing an anti-treeing compound.
  • Tubular Plate (Battery) - A positive plate which is composed of assembly of porous tubes of perforated metal or tissure with or without a central current collector spine. The active material is placed within the tube.
  • Tungsten Halogen Lamp - A gas-filled tungsten halogen lamp containing a certain proportion of halogens.
  • TW - 1) A thermoplastic insulated, moisture resistant conductor designed for use in wet or dry locations and an operating temperature of up to 60 degrees Celsius. 2) Trapezoidal Wire. Built as ACSR-TW or ACSS-TW, Trapezoidal Wire uses trapezoidal formed stran
  • Twenty A - See 20A.
  • Twenty B - See 20B.
  • Twenty C - See 20C.
  • Twisted Pair - Telephone companies commonly run twisted pairs of cooper wires to each customer household. The pairs consist of two insulated cooper wires twisted into a spiral pattern. These wires are capable of transferring both voice as well as data.



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