Your Heating Specialist since 1949
Glossary of Terms
GLOSSARY
Ampere – Unit of current ( flow ) ( I )= E / R AC – Alternating current .
Ampacity – The current-carrying capacity of the conductor under stated thermal conditions .*
Conductor – A conductor is the current-carrying , non-heat producing component of a heating element .*
Conduction – The transfer of energy within or between two bodies in physical contact .
Convection – The movement of a mass with its associated energy ( liquid or gas ) from one location to another .
DC – Direct Current .
Dielectric Strength – The ability of the electrical insulation to withstand an applied voltage .
Dielectric Breakdown – Dielectric breakdown is the voltage at which the dielectric strength of the insulating material falls below an acceptable level .*
Differential – For an on / off controller , it refers to the temperature difference between the temperature at which the heat is turned back on . It is expressed in degrees .
Element – An element is a resistor encased in an acceptable insulating material covered with a protective sheath .
Ground – A conducting connection between an electrical circuit or equipment and the earth or some conducting body that serves in place of the earth .*
Hazardous Location – Locations are classified depending on the properties of the flammable vapors , or gases , or combustible dusts , or fibers which may be present and the likelihood that a flammable or combustible concentration or quantity is present .*
Heat – Heat is energy in transition , or transfer , from one body to another by virtue of temperature difference existing between the bodies .
Heater – A heater is a completed , usable assembly containing one or more elements .
Heat of Fusion – Heat necessary to change solid to liquid .
Insulation – Any material that retards the transfer of heat to the environment or other components .
Insulation Resistance – Insulation resistance is the ability of the insulation to resist the percentage of current .*
Leakage – The undesirable passage of current flow through or over the surface of an insulator .
Leakage Current – the total electrical current flow from the resistor through or around the insulation to a point external to the resistor when the element is energized .*
OHM – The electrical unit of resistance ( R ) R = E / I
Parallel Circuit – A circuit in which the identical voltage is presented to all components and the current divides among the components according to the resistance or the impedance of components .
Radiation – The transfer of energy from one body to another through space by electromagnetic wave phenomena .
Rating – rating is the performance characteristic of an element or heater and is normally expressed in power output ( watts ) for a specific input voltage .
Resistor – A resistor is the heat-producing component of an element .*
Series Circuit – A circuit in which the components are arranged end to end to form a single path for current .
Single Phase – A system energized from a single alternating voltage .
Specific Heat – The heat energy in Btu ’ s required to change the temperature of one pound of a substance by 1 ° F .
Specific Gravity ( Gas ) – The ratio of the density of a gas to the density of air at 60 ° F and 14.7 PSIA .
Specific Gravity ( Liquid ) – The ratio of the density of a liquid to the density of water at 60 ° F and 14.7 PSIA .
Thermal Resistance – The property that opposes the flow of heat ( energy ) through the material .
Terminal – A terminal is the device or point at which external power is connected .*
Heat of vaporization – Heat necessary to change solid to gas .
Hertz – Unit of frequency of charge reversal for alternating current .
Hi-Pot – A high voltage quality assurance test performed on electrical components and systems .
Hysteresis – The temperature sensitivity designed into the on / off control action between the on and off switching points . Expressed in percentage of control range . Also known as dead band .
Impedance Heat – A system in which heat is generated in a pipeline or vessel wall by causing current to flow through the pipeline or vessel wall by direct connection to an AC voltage source from a dual-winding transformer .
Three Phase – A system energized from three substantially equal voltages that differ in phase by one-third cycle or 120 °.
Volt – Unit of electrical pressure . 1 volt is the amount of pressure that will cause one ampere of current in one OHM of resistance ( E ) E = IR
Watt – Unit of electrical power . One watt is equivalent to the power represented by one ampere of current under a pressure of one volt . ( W ) W = EI
Watt Density – Watt density is the output of the element or the resistor in watts per square inch of surface . On heating cable elements , watt density is expressed in watts per foot of cable .*
* NEMA Standard
APPENDIX
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