T2 Carrier System: A North American digital communications link that is formed by multiplexing three T1 systems and operates at 6.312 Mb/s. The European version is E2.

T3 Carrier System: A North American digital communications link that is formed by multiplexing seven T2 systems and operates at 47.736 Mb/s. The European version is E3.

TCP: Transmission Control Protocol. A transport layer protocol for the Internet.

TCP/IP: Transmission Control Protocol/Internet Protocol. This is a common shorthand which refers to the suite of application and transport protocols which run over IP. These include FTP, Telnet, SMTP, and UDP (a transport layer protocol).

TDM: Time Division Multiplexing.

Telemetry: Transmission and collection of data obtained by sensing conditions in a realtime environment.

TELNET: The Internet standard protocol for remote terminal connection service. Telnet allows a user at one site to interact with a remote timesharing system at another site as if the user's terminal was connected directly to the remote computer.

TEMPCO: Abbreviation for "temperature coefficient": the error introduced by a change in temperature. Normally expressed in %/°C or ppm/°C.

Temperature Error: The maximum change in output, at any measurand value within the specified range, when the transducer temperature is changed from room temperature to specified temperature extremes.

Temperature, Compensated: The range of temperature over which a transducer can operate up to full scale and still meet all specifications.

Temperature Compensation: The utilization of supplementary devices, materials, or components within the bridge to minimize sources of error caused by changing temperature.

Temperature, Operating: The range of temperature over which a transducer may be safely operated up to full scale without causing failure, but specificationsmay not be met.

Temperature Effect On Span: The change in rated output due to a change in ambient temperature. Usually expressed as +/- a percentage change in rated output per degree F change in ambient temperature over the compensated temperature range.

Temperature Effect On Zero: The change in zero balance due to a change in ambient temperature. Usually expressed as +/- a percentage change in rated output per degree F change in ambient temperature over the compensated temperature range.

Terminal: An input/output device used to enter data into a computer and record the output.

Thermal Coefficient of Resistance: The change in resistance of a semiconductor per unit change in temperature over a specific range of temperature.

Thermal Conductivity: The property of a material to conduct heat in the form of thermal energy.

Thermal emf: See Seebeck emf

Thermal Expansion: An increase in size due to an increase in temperature expressed in units of an increase in length or increase in size per degree, i.e. inches/inch/degree C.

Thermal Gradient: The distribution of a differential temperature through a body or across a surface.

Thermal Sensitivity Shift: The sensitivity shift due to changes of the ambient temperature from room temperature to the specified limits of the compensated temperature range.

Thermal Zero Shift: An error due to changes in ambient temperature in which the zero pressure output shifts. Thus, the entire calibration curve moves in a parallel displacement.

Thermistor: A temperature-sensing element composed of sintered semiconductor material which exhibits a large change in resistance proportional to a small change in temperature. Thermistors usually have negative temperature coefficients.

Thermocouple: The junction of two dissimilar metals which has a voltage output proportional to the difference in temperature between the hot junction and the lead wires (cold junction) (refer to Seebeck emf).

Thermopile: An arrangement of thermocouples in series such that alternate junctions are at the measuring temperature and the reference temperature. This arrangement amplifies the thermoelectric voltage. Thermopiles are usually used as infrared detectors in radiation pyrometry.

Thermowell: A closed-end tube designed to protect temperature sensors from harsh environments, high pressure, and flows. They can be installed into a system by pipe thread or welded flange and are usually made of corrosion-resistant metal or ceramic material depending upon the application.

Thomson Effect: When current flows through a conductor within a thermal gradient, a reversible absorption or evolution of heat will occur in the conductor at the gradient boundaries.

Token Passing: A protocol that gives a terminal permission to transmit on a Token Ring LAN. A unique bit pattern, called a token, circulates around the ring from terminal to terminal. The terminal that possesses the token has permission to transmit.

Token Ring: A LAN standard, also known as IEE 802.5, that connects a ring topology. Token Ring LANs operate at 4 Mb/s or 16 Mb/s.

TQM: Total Quality Management.

Transducer Vibration: Generally, any device which converts movement, either shock or steady state vibration, into an electrical signal proportional to the movement; a sensor.

Transducer: A device (or medium) that converts energy from one form to another. The term is generally applied to devices that take physical phenomenon (pressure, temperature, humidity, flow, etc.) and convert it to an electrical signal.

Transient Vibration: A temporary vibration or movement of a mechanical system.

Transitional Flow: Flow between laminar and turbulent flow, usually between a pipe Reynolds number of 2000 and 4000.

Transmitter: A transducer that has a 4-20 mA two wire output.

Transverse Sensitivity: Signal output as a result of acceleration perpendicular to the sensitive axis. Specified as a percentage of sensitive axis output for equivalent right angle acceleration or as a decimal fraction.

Triac: A solid state switching device used to switch alternating current wave forms.

Triple Point (Water): The thermodynamic state where all three phases, solid, liquid, and gas may all be present in equilibrium. The triple point of water is .01°C.

Triple Point: The temperature and pressure at which solid, liquid, and gas phases of a given substance are all present simultaneously in varying amounts.

True RMS: The true root-mean-square value of an AC or AC-plus-DC signal, often used to determine power of a signal. For a perfect sine wave, the RMS value is 1.11072 times the rectified average value, which is utilized for low-cost metering. For significantly non-sinusoidal signals, a true RMS converter is required.

TTL Unit Load: A load with TTL voltage levels, which will draw 40 µA for a logic 1 and -1.6 mA for a logic 0.

TTL-Compatible: For digital input circuits, a logic 1 is obtained for inputs of 2.0 to 5.5 V which can source 40 µA, and a logic 0 is obtained for inputs of 0 to 0.8 V which can sink 1.6 mA. For digital output signals, a logic 1 is represented by 2.4 to 5.5 V with a current source capability of at least 400 µA; and a logic 0 is represented by 0 to 0.6 V with a current sink capability of at least 16 mA.

TTL: Transistor-to-transistor logic. A form of solid state logic which uses only transistors to form the logic gates.

Turbulent Flow: When forces due to inertia are more significant than forces due to viscosity. This typically occurs with a Reynolds number in excess of 4000.

Twisted Pair: Two insulated wires, usually made from copper, that are twisted in a regular, six turns per inch spiral pattern used to connect most telephones. Also used as a medium by several local area networks.

Typical: Error is within plus or minus one standard deviation (±1%) of the nominal specified value, as computed from the total population.