We take content rights seriously. If you suspect this is your content, claim it here.
Available Formats
Download as PDF or read online on Scribd
You are on page 1/ 1
“The dasign ofthe WayCon capaciive sensors is based onthe fact hat the reactance of an ideal plats capector is proportona tothe distance between the pats,
‘The measurement sensor s a guard ing canactor ose quad ng iseaonected to he inne held ofthe dou sheked masurng cable Arnegabvefeecsack amplter
ep tis peotatve shel tne exact fo the polenta es the sans cantar slactrade.Th's ansures nthe ane meesurng range 29 sist homageneous fle Between
the capacitor plates and nearly complete independence of changes i cable capac Ian atrnaing cuTent of constant amplitude and Frequency passes though the sensor
‘capactor, the ampituge ofthe alerting voltage between the capac tor pales (elecuede of sensor and obec to be measured) is proporbonl fo he distance between the
th A 20 hz oscar of nghy constant amide and fequancy provses the sanecr current ms wel as 2 Compensating ottage uh can be selected ty means of
Precision patentometer. Through a lou pass filer and an ample the votage diference s conducted towards the ouput termina
‘As descrivedin the above section ofthe operaton ofthe distance meter, the measurement is affected by the properbes ofthe dielectne. General the sensor willbe used for
measurements im. The afea between te sensor aa te target shouldbe completely fee of dust, olor water If nocessaty t's an be achieved by blowing sorte ar
{through te gap between sensor and target
Measurements in liquids
‘When cary out measurements in iquds, which should only be done in special cases, one should consider thatthe measurements ae not only fected by dust ee. but
also by gas bubbles, The real distance i found by ruling the distance rovded by ine meter) wi the dielecine constant (epson ofthe ad Please also consider bat
‘gener the hslecic constants of ics ave temperate Gapendent and fat the dtecne losses of he ae sad must be negebe,'= theca must be naan,
“Targets with rough surfaces
|When targets have rough surfaces the cstance = measured rom the average profes long a the depth of the roushnass is small compared tothe distance mansured. The
_average distance i alse mesauredin casee where te target has s cured sue,
Influence of temperature
‘The main reason for this isthe longtudial elongation of the sensor material. Customised versions made of INVAR are avalable on request,
‘The maxumum operating temperature is Ifed j the maling temperature of the slcering matanaliside the conmecior Measurements at tremely low temperatures,
close tothe abcohde zero were successfull conducted with cu standard probes (Fa, Domi, FZ Karsrue, ETH Zurich).
Magnetic elds
Can benealected, as long as there is no exerion of force tothe measurement system. On request the sensor heads can be made of non-magnetic material, ike Titanium.
Radioactive radiation
has no inlusnce on messurements performed by capaciive censors, Approprts insulation matoras guarantee long tm operaten without fare,
Specific resistance
The relatively low carer fequency ofthe system allows measurement al materials in the micro ohm te kl chm range (uOhm cm up fo > 1000 Ohm cm) wiht spacial
recaltraton. Therefore tho whole rango of meacunng on siicon cemconduclee i also covered
“This fact as great felovanco wen meakunng on easchardaned ehafts in tie mocharvcal sngineaing socio. because an inhomogeneous miro stuctue has no nfuonce
contre measurement resuls. Tere is aost no Oe mod to crtrcl Uwe displacement of shalt running nol 2 sing bearing than by a eapactve sensor
Moasuroments on insulation material
The eapacive sensors can 9 be Used to measure the thickness of non conducive materials euch as lass, fal, quartz las, ceramics.
ec
‘heeds ach aes messes te average distance othe objec. The raginecs fan jects wee adomaicaly reaped by th eyo. This etre may bo of
‘advantage when smell smal rogues shoul nt be observed.
‘Customised probes (sensor heads)
Nig other messurementprinepie slows such chasp and simple adaptations of the probe housing or the active area accorcing ta the customer needs. The reason fr this
isthe pure mechanical constuction consisting of conducting slectaces and insulating barir sheets (plastics, ceramic, glass). Some examples ae shewn an page 3.
