More in­focen­ter top­ics: Ther­moacous­tics | Sig­nal pro­cessing | Visu­al­iz­a­tion

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.