W A T L O W

mica A silicate material used primarilyas an electrical and heat insulator. micron A unit of length. One micron isequivalent to 10

Glossary

Monel MDR See “relay, mercurydisplacement.”
® An alloy made of nickel andcopper sensor sheath that is used tomake sensor sheaths. It exhibitsexcellent resistance to sea water; tohydrofluoric, sulfuric and hydrochloric acids; and to most alkalis. Monel measuring junction See “junction.” measuring junction Thethermocouple junction that is affixed toor inserted into the material being measured. Also called hot junction.
-6 meters. microvolt (µV) One 10
-6 of a volt (one millionth in the US).
® is aregistered trademark of the SpecialMetals Corporation (formally Inco). mega (M) A prefix that means one 10 mil One thousandth of an inch, or0.001 inches in decimal form.
6 Mylar (one million in the US). multilayer hybrid A hybrid circuitconstructed of alternating conductiveand insulating layers. The multilayer structure combines very dense packaging of electronics with good ability to remove generated heat. Multilayers are typically built through repeated firings as layers are addedand are typically constructed withgold, silver-palladium or copper conductors. milled groove A machined groovemilled into a part to accept a heatershaped to fit the groove. megawatt (MW) 1x10
6 watts or1,000,000 (one million) watts. melting point The temperature atwhich a substance changes from asolid to liquid state. This is the same as the freezing point of pure materials. milliampere (mA) One 10
-3( thousandth) of an ampere. menu A list of options from which theoperator can select the tasks to bedone. millivolt (mV) One 10
-3 (thousandth)of a volt. mineral insulated thermocouple Athermocouple probe constructed byloading a metal sheath withthermocouple conductors and a mineral-based dielectric material, thencompacting the entire assembly. mercury displacement relay (MDR) A power switching device in whichmercury, displaced by a plunger, completes the electric circuit acrosscontacts.
® Terephtalate (polyester) film. Aregistered trademark of the E.I. duPontde Nemours & Company. metal fatigue A breakdown in metalstrength caused by mechanical action.For example, when sheath and conductor materials have differentlinear expansion coefficients, heating and cooling cause mechanical movement that induces strain. Metalfatigue shortens the life of the heater and the thermocouple. minimum load current The smallestload current required to ensure properoperation of an output switching device. MGT Mica Glass Teflon minimum output impedance See“offstate impedance.”

N

MNPT informal; Male (external)National Pipe Thread.
Glossary National Bureau of Standards (NBS)Now called the National Institute ofStandards Technology (NIST). MO Magnesium Oxide. Thepowdered chemical compound usedin heater manufacturing to insulate theresistance wire from the metal sheath. This high grade material alsocontributes to the long life of Watlowheaters. National Electrical Code (NEC) A setof specifications devised for the safeapplication and use of electric power and devices in the United States. National Electrical ManufacturersAssociation MODBUS (NEMA) A United Statesassociation that establishesspecifications and ratings for electricalcomponents and apparatuses.Conformance by manufacturers isvoluntary.
® . An optionalheater lead wire covering, used withseveral Watlow heater lines, made withmica, fiberglass and a Teflon
® binder. MI leads Mineral Insulated leads. AWatlow LA (Lead Adaptor) terminationoption for cartridge heaters thathandles both high temperatures up to815°C (1,500°F) and contamination,such as moisture, gases, oils, plastic drool, solvents and water.
™ protocol driver Asoftware program subroutine thatconverts programming language- oroperating system-specific instructions to the MODBUS™ protocol for aMODBUS™ device. National Institute of Standards andTechnology (NIST) A United Statesgovernment agency responsible forestablishing scientific and technicalstandards. Formerly the National Bureau of Standards. National Pipe Thread (NPT) Thetaper pipe thread standard used inNorth America. MIB Management Information Base Adatabase of defined properties ofobjects that can be monitored or manipulated by a network administrator via an SNMP agent. moisture resistance The relativeability to resist permeation by water. 201