MLT-1000'User'Manual'Overview'
Excel!Technology!Co!Page!3!
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The! Excel! Technology! Co!MLT-1000! is! a! portable! field! service! device! for! in-pavement! loop! analysis.! It! is!
capable! of! measuring! loop! inductance,! DC! series! resistance,! Q! performance! factor! and! loop! resonant!
frequency!for!a!group!of!up!to!eight!in-pavement!loops.!It!can!also!detect!open!and!short!circuit!conditions.!
The! MLT-1000! is! based! on! Excel! Technology! Co’s! LTM-100! basic! loop! tester.! The! MLT-1000! includes!
additional!switching!circuitry!that!allows!up!to!eight!in!pavement!loops!to!be!measured!simultaneously.!The!
device! is! also! capable! of! measuring! loops! while! traffic! is! flowing! by! filtering! out! vehicles! from! the!
measurements.!The!device!is!powered!and!controlled!by!accompanying!PC!software!via!a!USB!connection.!
The! software! allows! the! user! to! easily! log! and! save! loop! data!and! store! it! along! with! relevant! site!
information.!
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In-pavement! induction! loops! can! be! characterised! by! their! inductance! and! DC! resistance.! The! overall!
sensitivity!of!the!loop!is!measured!by!a!performance!factor!Q.!!
Inductance! is! a! property! of! a! conductor! that! opposes! a! change! in! current.! Inductance! is! measured! in!
Henries!(H),!but!is!commonly!displayed!in!Microhenries!(µH).!Inductance!depends!on!the!size,!number!of!
turns,! configuration! of! the! loop,! length! of! the! feeder! cable! and! environmental! factors! (e.g.! steel!
reinforcement!in!road,!temperature).!
DC! series! resistance! is! a! property! of! a! conductor! that! opposes! current! flow.! The! resistance! of! a! wire!
depends!on!its!material,!cross-sectional!area!and!length.!!Therefore,!an!inductive!loop!using!thin!cable!with!
a!large!number!of!turns!and!a!long!feeder!cable!is!likely!to!have!a!high!DC!series!resistance.!!
The!Q!performance!factor!of!a!loop!is!effectively!a!relationship!between!the!inductance!of!a!loop!and!the!
resistance/impedance!of!the!feeder!cable.!The!Q-factor!is!calculated!as:!
𝑄 = 2×𝜋×𝑓𝑟𝑒𝑞𝑢𝑒𝑛𝑐𝑦×𝐼𝑛𝑑𝑢𝑐𝑡𝑎𝑛𝑐𝑒
𝑟𝑒𝑠𝑖𝑠𝑡𝑎𝑛𝑐𝑒 !
The!higher!the!Q-factor,!the!more!sensitive!the!loop!is.!Therefore,!if!the!resistance!of!the!loop!and!feeder!
cable!is!large,!then!the!inductance!must!be!large!to!maintain!high!sensitivity.!For!vehicle!detection,!the!Q-
factor!of!a!loop!should!be!in!the!range!below!for!the!corresponding!frequency!ranges:!
Q-factor!=!5!to!50!for!Frequency!<!60!kHz!
Q-factor!=!3!to!50!for!Frequency!≥!60!kHz!
For!reliable!vehicle!classification!or!identification,!the!Q-factor!should!be!in!the!range!15!to!50.!
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