Kutheni 4-20mA?

Yintoni i-4-20mA?

Umgangatho wesignali we-4-20mA DC (1-5V DC) uchazwa yi-International Electrotechnical Commission (IEC) kwaye isetyenziselwa iimpawu ze-analog kwiinkqubo zolawulo lwenkqubo.

Ngokubanzi, i-signal current yezixhobo kunye neemitha imiselwe kwi-4-20mA, kunye ne-4mA emele ubuncinci obukhoyo kunye ne-20mA emele ubuninzi bangoku.

Kutheni imveliso yangoku?

Kuseto lwemizi-mveliso, ukusebenzisa iamplifier yomqondiso ukuya kwimeko kunye nokuhambisa imiqondiso kumgama omde usebenzisa imiqondiso yombane kunokukhokelela kwimiba emininzi. Okokuqala, iisignali zombane ezigqithiselwa phezu kweentambo zinokuba sesichengeni sokuphazamiseka kwengxolo. Okwesibini, ukuchasana okusasazwa kwemigca yokuhambisa kunokubangela ukuhla kwamandla ombane. Okwesithathu, ukunika amandla kwi-amplifier yomqondiso kwintsimi kunokuba ngumngeni.

Ukujongana nale miba kunye nokunciphisa impembelelo yengxolo, i-current isetyenziselwa ukuhambisa imiqondiso kuba ayibonakali kancinci kwingxolo. I-4-20mA loop yangoku isebenzisa i-4mA ukumela i-zero signal kunye ne-20mA ukumela isignali egcweleyo, kunye neempawu ezingaphantsi kwe-4mA nangaphezulu kwe-20mA esetyenziselwa i-alamu ehlukeneyo.

Kutheni sisebenzisa i-4-20mA DC (1-5V DC)?

Izixhobo zentsimi zinokusebenzisa inkqubo yeentambo ezimbini, apho ukunikezelwa kwamandla kunye nomthwalo zidibaniswe ngokulandelelana kunye nenqaku eliqhelekileyo, kwaye iingcingo ezimbini kuphela zisetyenziselwa ukunxibelelana komqondiso kunye nokunikezelwa kwamandla phakathi komthumeli wentsimi kunye nesixhobo sokulawula igumbi. Ukusebenzisa isignali ye-4mA ye-DC njengesiqalo sangoku sinika i-static yokusebenza ngoku kwi-transmitter, kunye nokuseta indawo ye-zero yombane kwi-4mA DC, engahambelani nendawo ye-zero yomatshini, ivumela ukufunyanwa kweempazamo ezifana nokulahlekelwa kwamandla kunye nokuqhawula intambo. . Ukongezelela, inkqubo yeentambo ezimbini ifanelekile ekusebenziseni izithintelo zokhuseleko, inceda ekukhuseleni ukuqhuma.

Izixhobo zegumbi lokulawula zisebenzisa i-voltage-parallel signal transmission, apho izixhobo zenkqubo yolawulo efanayo zabelana nge-terminal efanayo, okwenza kube lula ukuvavanywa kwesixhobo, uhlengahlengiso, ujongano lwekhompyuter kunye nezixhobo ze-alam.

Isizathu sokusebenzisa i-4-20mA DC yokunxibelelana komqondiso phakathi kwezixhobo zentsimi kunye nezixhobo zegumbi lokulawula kukuba umgama phakathi kwentsimi kunye negumbi lokulawula unokubaluleka, okukhokelela ekuchaseni ikhebula eliphezulu. Ukuhanjiswa kweempawu zombane kwimigama emide kunokubangela iimpazamo ezibalulekileyo ngenxa yokuhla kwamandla ombane okubangelwa ukuchasana kwentambo kunye nokumelana nokufakwa kwesixhobo esifumanayo. Ukusebenzisa isignali yomthombo wangoku ngokuqhubekayo kwi-remote transmission iqinisekisa ukuba i-current in loop ihlala ingatshintshi kungakhathaliseki ukuba ubude bentambo, iqinisekisa ukuchaneka kokuhanjiswa.

Isizathu sokusebenzisa isignali ye-DC ye-1-5V yokudibanisa phakathi kwezixhobo zegumbi lokulawula kukuququzelela izixhobo ezininzi ezifumana umqondiso ofanayo kunye nokunceda kwi-wiring kunye nokwenza iinkqubo ezahlukeneyo zokulawula eziyinkimbinkimbi. Ukuba umthombo wangoku usetyenziswa njengomqondiso woqhagamshelo, xa izixhobo ezininzi zifumana umqondiso ofanayo ngaxeshanye, ukuchasana kwegalelo labo kufuneka kuqhagamshelwe kuthotho. Oku kuya kugqithisa umthamo womthwalo wesixhobo sokudlulisa, kwaye amandla omhlaba wesignali wezixhobo ezifumanayo aya kwahluka, ukwazisa ukuphazamiseka kunye nokuthintela unikezelo lwamandla oluphakathi.

Ukusebenzisa isignali yomthombo wombane wonxibelelwano kufuna ukuguqula isignali yangoku esetyenziselwa unxibelelwano kunye nezixhobo zentsimi ibe ngumqondiso wombane. Eyona ndlela ilula kukudibanisa i-standard 250-ohm resistor kuthotho kwisekethe yokuhambisa yangoku, ukuguqula i-4-20mA DC ukuya kwi-1-5V DC. Ngokuqhelekileyo, lo msebenzi ufezwa ngumthumeli.

Lo mzobo usebenzisa i-250-ohm resistor ukuguqula i-4-20mA isignali yangoku kwi-signal voltage ye-1-5V, kwaye emva koko isebenzisa i-RC filter kunye ne-diode exhunywe kwi-pin yokuguqula i-AD ye-microcontroller.

“Apha kuqhotyoshelwe umzobo wesekethe olula wokuguqula isiginali yangoku eyi-4-20mA ibe ngumqondiso wombane:

Kutheni le nto i-transmitter ikhethwa ukuba isebenzise i-4-20mA DC isignali yosasazo?

1. Iingqwalasela zokhuseleko lweendawo ezinobungozi: Ukhuseleko kwiindawo ezinobungozi, ngokukodwa kwizixhobo ezinokuthi ziqhume, zifuna ukunciphisa ukusetyenziswa kwamandla angatshintshi kunye nokutshintsha okuyimfuneko ukugcina isixhobo sisebenza. Iitransmitha ezikhupha isiginali ye-4-20mA ye-DC eqhelekileyo zisebenzisa umbane we-24V DC. Ukusetyenziswa kwamandla ombane e-DC ubukhulu becala kuba kuphelisa imfuneko yee-capacitors ezinkulu kunye ne-inductors kwaye igxile kwi-capacitance esasazwayo kunye ne-inductance yeentambo zokudibanisa phakathi komthumeli kunye nesixhobo sokulawula igumbi, elingaphantsi kakhulu kunomlilo wegesi ye-hydrogen.

2. Ukuhanjiswa komthombo wangoku kukhethwa ngaphezu komthombo wamandla ombane: Kwiimeko apho umgama phakathi kwebala kunye negumbi lokulawula ukhulu, ukusetyenziswa kweempawu zomthombo wamandla ombane ukuhambisa kunokwazisa iimpazamo ezibalulekileyo ngenxa yokuhla kwamandla ombane okubangelwa ukuxhathisa kwentambo kunye negalelo. ukuchasana kwesixhobo esifumanayo. Ukusebenzisa isignali yomthombo yangoku yokuhanjiswa okude iqinisekisa ukuba i-current in the loop ihlala ihleli, kungakhathaliseki ubude bekhebula, ngaloo ndlela igcina ukuchaneka kokuhanjiswa.

3. Ukukhethwa kwe-20mA njengobona bukhulu bangoku: Ukukhethwa kowona mgangatho uphezulu wangoku we-20mA kusekelwe kwingqwalasela yokhuseleko, ukusetyenziswa kombane, kunye neendleko. Izixhobo ezinobungqina bokudubula zingasebenzisa kuphela i-voltage ephantsi kunye nephantsi yangoku. I-4-20mA yangoku kunye ne-24V DC ikhuselekile ekusebenziseni phambi kweegesi ezinokutsha. Irhasi yehydrogen ene-24V DC yi-200mA, iphezulu kakhulu kune-20mA. Ukongeza, izinto ezinjengomgama phakathi kwezixhobo zesiza sokuvelisa, umthwalo, ukusetyenziswa kwamandla, iimfuno zecandelo lombane, kunye neemfuno zobonelelo lwamandla zithathelwa ingqalelo.

4. Ukukhethwa kwe-4mA njengesiqalo sangoku: Uninzi lwabathumeli abaphuma kwi-4-20mA basebenza kwi-system ye-wire-wire, apho ukunikezelwa kwamandla kunye nomthwalo zidibaniswe ngokulandelelana kunye nenqaku eliqhelekileyo, kwaye iingcingo ezimbini kuphela zisetyenziselwa ukunxibelelana ngomqondiso. kunye nokunikezelwa kwamandla phakathi komthumeli wentsimi kunye nesixhobo sokulawula igumbi. Ukukhetha i-4mA yokuqala yangoku ibalulekile ukuze isekethe yothumelo isebenze. I-4mA yokuqala yangoku, engahambelani nendawo ye-zero yomatshini, inika "indawo ye-zero esebenzayo" enceda ukuchonga iimpazamo ezifana nokulahlekelwa kwamandla kunye nokuqhawulwa kwentambo.

Ukusetyenziswa kweempawu ze-4-20mA kuqinisekisa ukuphazamiseka okuncinci, ukhuseleko, kunye nokuthembeka, okwenza kube ngumgangatho owamkelwe ngokubanzi kwizicelo zoshishino. Nangona kunjalo, ezinye iifomati zesignali zemveliso, ezifana ne-3.33mV / V, 2mV / V, 0-5V, kunye ne-0-10V, nazo zisetyenziselwa ukuphatha kakuhle iimpawu zenzwa kunye nokuxhasa iinkqubo ezahlukeneyo zokulawula.