Magnetics Business & Technology - March/April 2020 - 16

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Capacitive effects are integrated around the full circumference of
the ring-shaped components, so that measurements are largely
insensitive to dust, moisture of minor misalignments.
$WWKHKHDUWRIWKHPXOWLWXUQV\VWHPLV:LHJDQGHQHUJ\KDUYHVWing technology. To accommodate the open-center layout, a new
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H[WHQVLYH PDJQHWLF ¿HOG VLPXODWLRQ D UHOLDEOH VROXWLRQ ZDV GHveloped that included four diametrical-oriented magnets placed
evenly around the rotor. These four magnets provide a stable
PDJQHWLF¿HOGWKDWWULJJHUVSRODULW\UHYHUVDOVLQWKH:LHJDQGVHQsor installed in the stator.
:LWKHDFKGHJUHHURWDWLRQRIWKHURWRUWKH:LHJDQGDVVHPbly generates a current pulse that energizes the counting electronics. This counter has a 43-bit memory for a measurement
range of almost nine trillion revolutions. "These are values that
put us right on trend for our target market," says Leeser.
tŝĞŐĂŶĚīĞĐƚdĞĐŚŶŽůŽŐǇ
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the unique magnetic property of specially processed, small ferURPDJQHWLFZLUH-RKQ:LHJDQGGLVFRYHUHGDZD\WRFDXVHWKH
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used as a power source.

A-to-B Applying a reYHUVH ¿HOG VZLWFKHV WKH
core's polarity, producing a
large voltage spike.
B-to-C As the reverse
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the shell eventually switches polarity, giving rise to a
smaller pulse in the same
direction.

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Vicalloy, a ferromagnetic alloy of cobalt, iron, and vanadium. Initially, the wire is fully annealed. In this state the alloy is "soft"
in the magnetic sense; that is, it is attracted to magnets and so
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During manufacture, to give the wire its unique magnetic properties, it is subjected to a series of twisting and untwisting operations to cold-work the outside shell of the wire while retaining a
soft core within the wire, and then the wire is aged. The result is
that the magnetic coercivity of the outside shell is much larger
than that of the inner core. This high coercivity outer shell will
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source is removed.
7KHZLUHQRZH[KLELWVDYHU\ODUJHPDJQHWLFK\VWHUHVLV,IDPDJQHW LV EURXJKW QHDU WKH ZLUH WKH KLJK FRHUFLYLW\ RXWHU VKHOO H[FOXGHVWKHPDJQHWLF¿HOGIURPWKHLQQHUVRIWFRUHXQWLOWKHPDJnetic threshold is reached, whereupon the entire wire - both the
outer shell and inner core - rapidly switches magnetisation polarity. This switchover occurs in a few microseconds, and is called
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XVLQJ D :LHJDQGZLUH FRUH %HFDXVH WKH YROWDJH LQGXFHG E\ D
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WKH¿HOGD:LHJDQGZLUHFRUHFDQLQFUHDVHWKHRXWSXWYROWDJHRI
DPDJQHWLF¿HOGVHQVRUE\VHYHUDORUGHUVRIPDJQLWXGHDVFRPSDUHGWRDVLPLODUFRLOZLWKDQRQ:LHJDQGFRUH7KLVKLJKHUYROWage can easily be detected electronically, and when combined
ZLWKWKHKLJKUHSHDWDELOLW\WKUHVKROGRIWKHPDJQHWLF¿HOGVZLWFKLQJPDNLQJWKH:LHJDQGHIIHFWXVHIXOIRUSRVLWLRQDOVHQVRUV
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into account.
For more info, see www.posital.com and www.wikipedia.org.

C-to-D After saturating
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D-to-E Applying a magQHWLF ¿HOG ZLWK WKH RULJLQDO
polarity of the wire switches the core once again
generating a large pulse in
the opposite direction.

E-to-F Increase of the
HWHUQDO¿HOGZLOODOVRVZLWFK
shell polarity.
The wire is back in the
original state A and a full
cycle completed.

Magnetics Business & Technology *

March/April 2020

Blog Contributors Needed
0DJQHWLFV%XVLQHVV 7HFKQRORJ\LVORRNLQJIRUNQRZOedgeable professionals in the magnetics industry who'd
like to contribute to our guest blog to be featured on the
website. Your blog will be featured in the month it's published on the website.
For more info email scottw@webcomcommunications.com.

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Magnetics Business & Technology - March/April 2020

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