B

Boiling Point: The equilibium temperature between a liquid and a gaseous state. For example, the boiling point of water is 100°C (212°F) at standard atmosphere pressure.

C

Celsius (C): Formerly known as Centigrade. A temperature scale in which water freezes at 0°C and boils at 100°C at standard atmospheric pressure. The formula for conversion to the Fahrenheit scale is: °F = (1.8 x °C) + 32.

Ceramic Insulation: Materials made of metal oxides that are capable of withstanding high temperatures and providing the desired dielectric strength. They are used to insulate heater elements.

Conduction: A term used to indicate a device whose contacts must close with rising temperatures.

Convection: A mode of heat transfer in a fluid (gas or liquid) in which heat is transferred through movement of masses of the fluid from a region of higher temperature to one of lower temperature.

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D

Dielectric: An insulating material with very low electrical conductivity.

Dielectric Breakdown : The point at which a dielectric substance becomes conductive. Usually a castastrophic insulation failure caused by excessive voltage.

Dielectric Strength : The potential gradient at which electric failure or breakdown occurs. Also known as breakdown potential.

E

Explosion-Proof Enclosure: An enclosure designed to withstand an explosion of gases inside, to isolate sparks inside from explosive or flammable substance outside, and to maintain an external temperature that will not ignite surrounding flammable gases or liquids.

F

Fahrenheit: The temperature scale that sets the freezing point of water at 32F and its boiling point at 212F at standard atmospheric pressure. The formula for conversion to Celsius is: °C = 5/9 (°F - 32°F).

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G

Ground: An electrical line with the same electrical potential as the surrounding earth. Electrical systems are usually grounded to protect people and equipment from shocks due to malfunctions. Also called "safety ground".

H

Heat: Energy transferred between material bodies as a result of a temperature difference between them.

Heat Transfer: The flow of heat energy from one body of higher temperature to one of lower temperature.

Hi-Pot Test: A test that applies a high voltage to a conductor to assure the integrity of the surrounding insulation. See "Dielectric Breakdown".

K

Kilowatt: (kW) Unit of electrical power equal to 1,000 watts or 3,412 BTUs per hour when the power factor equals1.0.

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M

Manual Reset: A feature on a limit control that requires human intervention to return the limit to normal operation aftera liimit condition has occurred.

Mica: A silicate material used primariily as an electric and heat insulator.

N

Neoprene: A synthetic rubber, also referred to as polychloroprene, that exhibits good resistance to oil, chemicals and flame.

NPT: American National Standard Taper Pipe Thread as defined by ANSI B1.20.1.

O

O.D.: Outside diameter.

Ohm: (Ω) The unit of electrical resistance. The resistance value through which one volt will maintain a current of one ampere.

On-Off: A method of control that turns the output full on until set point is reached, and then off until the process error exceeds the hysteresis.

On-Off Controller: A temperature controller that operates in either full-on or full-off state.

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P

Parallel Circuit: A circuit configuration in which the same voltage is applied to all components, with current divided among the components according to their respective resistances or impedances.

Phase: The time-based relationship between alternating current cycles and a fixed reference point. In electricity, it is usually expressed in angular degrees, with a complete cycle equal to 360°. It describes the relationships of voltage and current of two or more alternating waveforms.

Potting: The sealing of components and associated conductors with a compound to exclude moisture and contaminants.

R

Resistance: Opposition to the flow of electric current, measured in ohms.

S

Safety Limit: An automatic limit intended for use in applications where an over-temperature fault may cause a fire or pose other safety concerns.

Series Circuit: A circuit configuration in which a single current path is arranged among all components.

Swage: Uniform compaction process that decreases the diameter and increases the length of a cylinder.

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T

Temperature, Ambient: The temperature of the air or other medium that surrounds the components of a thermal system.

Thermowell: A tube with a closed end that is designed to protect temperature sensors from hostile environments.

V

Voltage: (V) The difference in electrical protential between two points in a circuit. It's the push or pressure behind current flow through a circuit. One volt (V) is the difference in potential required to move one coulomb of charg between two points in a circuit, consuming one joule of energy. In other words, one volt (V) is equal to one ampere of current (I) flowing through one ohm of resistance (R), or V = IR.

W

Watt: (W) A measurement of real power. The product of voltage and current in a resistive circuit. VI = P, where V is volts, I is current in amperes and P is power in watts.

Watt Density: The watts of power produced per unit of surface area of a heater. Watt density indicates the potential for a surface to transmit heat energy and is expressed in W/in² or W/cm².

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