More in­fo­cen­ter top­ics: Ther­moa­cous­tics | Sig­nal pro­cess­ing | Visu­al­iza­tion

Über die Tordierung eines Wel­lenseg­ments kann das aufgelegte Drehmo­ment gemessen wer­den. Dazu wird der Ver­drehwinkel zwis­chen den Enden des Seg­ments mit der Tor­sion­ssteifigkeit des Seg­ments mul­ti­pliziert. Während dem Betrieb kann der Ver­drehwinkel mit der Ein­gangskarte IFTA AT2, in Kom­bi­na­tion mit Inkre­men­tal­ge­bern oder Trig­gersen­soren, aus­ge­le­sen wer­den.

Wie das Drehmo­ment ro­bust und akku­rat bes­timmt wird, beschreiben wir in un­serem Whitepa­per.



ATEX cer­ti­fied prod­ucts must meet strict qual­i­ty and safe­ty re­quire­ments for use in po­ten­tial­ly ex­plo­sive en­vi­ron­ments.

The term ATEX stands for the ab­bre­vi­a­tion of the French term "at­mo­sphères ex­plosi­bles" and is also an ab­bre­vi­a­tion for the Euro­pean Direc­tive 2014/34/EU, which aims to guar­an­tee a uni­form level of safe­ty in the field of ex­plo­sion pro­tec­tion.

The IFTA ChargeAm­pli­fi­er is also avail­able in an ATEX ver­sion for use in po­ten­tial­ly ex­plo­sive at­mos­pheres.

Dif­fer­en­tial mea­sure­ment is a method that is as tol­er­ant as pos­si­ble to in­ter­fer­ence ra­di­a­tion. The sig­nal is trans­mit­ted on two con­duc­tors with dif­fer­ent po­lar­i­ty in­stead of on one con­duc­tor, e.g. with nor­mal BNC con­nec­tions. It is also called sym­met­ri­cal or dif­fer­en­tial sig­nal trans­mis­sion. The re­ceiv­er de­ter­mines the use­ful sig­nal by dif­fer­ence for­ma­tion be­tween the two sig­nal con­duc­tors where­by ra­di­at­ed in­ter­fer­ences can­cel each other out. Thus it is a trans­mis­sion which is ro­bust against in­ter­fer­ences. Espe­cial­ly in charge mea­sure­ment this is ad­van­ta­geous as the sig­nal is very small in re­la­tion to pos­si­ble in­ter­fer­ences. It is there­fore used, for ex­am­ple, in high-tem­per­a­ture sen­sors.

In mea­sure­ment tech­nol­o­gy, gal­van­ic iso­la­tion refers to the po­ten­tial-free iso­la­tion be­tween the mea­sure­ment chain and the mea­sure­ment sys­tem. It pro­tects the mea­sur­ing in­puts and pre­vents hum loops. Par­tic­u­lar­ly in the case of large ma­chines, a dif­fer­ent po­ten­tial can exist at dif­fer­ent mea­sur­ing points of the ma­chine. Without sep­a­ra­tion, a com­pen­sat­ing cur­rent would flow through the mea­sur­ing de­vice to which the mea­sure­ment chains are con­nect­ed.

The sep­a­ra­tion can be ana­log or dig­i­tal. Ana­log iso­la­tion am­pli­fiers can eas­i­ly be con­nect­ed be­tween the input of the mea­sur­ing in­stru­ment and the mea­sure­ment chain, but lead to in­creased noise. It is bet­ter to sep­a­rate the input sig­nals after they have been con­vert­ed from ana­log to dig­i­tal. A sep­a­rate sep­a­ra­tion for each input chan­nel is ideal. In the case of low-cost mea­sure­ment tech­nol­o­gy, the gal­van­ic iso­la­tion is usu­al­ly miss­ing or not im­ple­ment­ed in­di­vid­u­al­ly for each chan­nel.

The IFTA input and out­put mod­ules all have a gal­van­ic iso­la­tion, for the AD4 mod­ules even per chan­nel.

In­te­grat­ed Elec­tron­ic Piezo Elec­tric (IEPE) rep­re­sents an in­dus­try stan­dard for high­ly sen­si­tive piezo­elec­tric sen­sors with in­te­grat­ed im­ped­ance con­vert­er elec­tron­ics. By means of an in­te­grat­ed charge am­pli­fi­er, high-im­ped­ance sig­nals of the sen­sor are con­vert­ed into low-im­ped­ance volt­age sig­nals and can be trans­mit­ted al­most loss- and in­ter­fer­ence-free over long lines. The abil­i­ty to in­te­grate sup­ply cur­rent and sen­sor sig­nal in a sin­gle coax­i­al cable is par­tic­u­lar­ly note­wor­thy. This is achieved by a sim­ple su­per­po­si­tion of di­rect cur­rent as sup­ply cur­rent and al­ter­nat­ing cur­rent as sen­sor sig­nal.

This stan­dard is ap­plied to sen­sors such as ac­cel­er­a­tion, force and pres­sure sen­sors or mi­cro­phones and dif­fers in its des­ig­na­tion de­pend­ing on the man­u­fac­tur­er.

ICP© (in­te­grat­ed cir­cuit piezo­elec­tric), CCLD© (con­stant-cur­rent line-drive), IsoTron© or DeltaTron© are some ex­am­ples.

The IFTA AD4-IEPE and AD4Pro mod­ules offer the op­tion­al soft­ware switch­able IEPE power sup­ply and can be used to power cor­re­spond­ing sen­sors or charge am­pli­fiers such as the IFTA ChargeAm­pli­fi­er.

In elec­tri­cal mea­sure­ment tech­nol­o­gy, a charge am­pli­fi­er or charge-volt­age chang­er serves the pur­pose of con­vert­ing most­ly small charges into a pro­por­tion­al volt­age. For this rea­son, charge am­pli­fi­ca­tion is par­tic­u­lar­ly used in areas where ex­treme­ly low charge quan­ti­ties have to be mea­sured, such as in piezo­elec­tric sen­sors.

The IFTA ChargeAm­pli­fi­er al­lows the am­pli­fi­ca­tion of dif­fer­en­tial charge sig­nals.

Sen­sor crack­­ers ("pop­­corn ef­­fect") pose a par­tic­u­lar chal­lenge for the charge am­p­li­­fic­a­­tion of high-tem­per­at­ure sen­sors. They occur when such a sen­sor is heat­ed so quick­ly that ther­mal stress­es build up in the piezo ele­­ment. If the ma­ter­i­al sud­­den­ly re­lax­es, large amounts of charge are sud­­den­ly re­leased. In sim­ple charge am­p­li­­fi­ers, the so-called py­ro­­elec­tric ef­­fect can also over­­drive the elec­tron­ics for sec­onds and thus ef­­fec­t­ive­ly blind them.

The shield­ing of elec­tron­ic de­vices means the sep­a­ra­tion of elec­tri­cal and mag­net­ic fields from or to these de­vices in order to en­sure in­ter­fer­ence-free sig­nal trans­mis­sion and pro­cess­ing.

The input and out­put mod­ules of the IFTA allow a shield to be con­nect­ed and thus en­able the ap­pro­pri­ate ground­ing con­cept to be im­ple­ment­ed.

The ap­plied torque can be mea­sured via the tor­sion of a shaft seg­ment. For this pur­pose, the tor­sion angle be­tween the ends of the seg­ment is mul­ti­plied by the tor­sion­al stiff­ness of the seg­ment. Dur­ing op­er­a­tion, the tor­sion angle can be read out with the input mod­ule IFTA AT2 in com­bi­na­tion with in­cre­men­tal en­coders or trig­ger sen­sors.