RDI67 series VFD (Variable-frequency Drive) – Ulawulo lweFan/Impompo yamanzi

I-converter frequency iqulunqwe kakhulu yi-rectifier (i-AC ukuya kwi-DC), i-filter, i-inverter (i-DC ukuya kwi-AC), iyunithi ye-braking, iyunithi yokuqhuba, iyunithi yokufumanisa, iyunithi yokucubungula i-micro, njl. ngokwaphula i-IGBT yangaphakathi, kwaye ibonelela ngamandla ombane afunekayo ngokweemfuno zangempela zemoto ukufezekisa injongo yokonga amandla kunye nokulawulwa kwesantya.Ukongeza, i-inverter inemisebenzi emininzi yokukhusela, efana ne-overcurrent, overvoltage, ukhuseleko lomthwalo, njl.


  • RDI67 series VFD (Variable-frequency Drive) – Ulawulo lweFan/Impompo yamanzi
  • RDI67 series VFD (Variable-frequency Drive) – Ulawulo lweFan/Impompo yamanzi
  • RDI67 series VFD (Variable-frequency Drive) – Ulawulo lweFan/Impompo yamanzi
  • RDI67 series VFD (Variable-frequency Drive) – Ulawulo lweFan/Impompo yamanzi
  • RDI67 series VFD (Variable-frequency Drive) – Ulawulo lweFan/Impompo yamanzi

Iinkcukacha zeMveliso

Isicelo

Iiparamitha

Iisampulu kunye neZakhiwo

Imilinganiselo

Intshayelelo yeMveliso

I-converter frequency iqulunqwe kakhulu yi-rectifier (i-AC ukuya kwi-DC), i-filter, i-inverter (i-DC ukuya kwi-AC), iyunithi ye-braking, iyunithi yokuqhuba, iyunithi yokufumanisa, iyunithi yokucubungula i-micro, njl. ngokwaphula i-IGBT yangaphakathi, kwaye ibonelela ngamandla ombane afunekayo ngokweemfuno zangempela zemoto ukufezekisa injongo yokonga amandla kunye nokulawulwa kwesantya.Ukongeza, i-inverter inemisebenzi emininzi yokukhusela, efana ne-overcurrent, overvoltage, ukhuseleko lomthwalo, njl.

Iimbonakalo

1. Ugcino lwamandla okutshintsha rhoqo

2. Ukugcinwa kwamandla okuhlawulela imbuyekezo yamandla - ngenxa yendima ye-capacitor yangaphakathi yokucoca i-inverter, ilahleko yamandla esebenzayo iyancitshiswa kwaye amandla asebenzayo egridi ayanda.

3. Ukonga amandla okuqalisa okuthambileyo - usebenzisa umsebenzi wokuqalisa othambileyo woguqulelo olujikelezayo uya kwenza isiqalo sangoku sangoku ukusuka kwi-zero, kwaye ixabiso eliphezulu aliyi kudlula umlinganiselo wangoku, ukunciphisa impembelelo kwigridi yamandla kunye neemfuno zokunikezelwa kwamandla ombane. , kunye nokwandisa ubomi benkonzo yezixhobo kunye neevalvu.Iindleko zokulondolozwa kwesixhobo zigciniwe.

Umzekelo No.

5

Imeko yokusebenza eqhelekileyo kunye nemeko yokufakela

2.1 Ukufuma: Ukufuma okunxulumeneyo akufunekanga kudlule kwi-50% kubushushu obuphezulu obungama-40°C, kwaye ukufuma okuphezulu kunokwamkelwa kwiqondo lobushushu elisezantsi.Ukujiya kufuneka kuthathelwe ingqalelo okubangelwa kukutshintsha kobushushu.
Xa iqondo lobushushu lingaphezulu kwe +40°C, i-action kufuneka ingene kakuhle.Xa okusingqongileyo kungafanelekanga, nceda usebenzise i-telecontrol okanye ikhabhathi yombane.Ubomi bokusebenza be-inverter buchatshazelwa yindawo yokufaka.Ixesha elide eliqhubekayo lisebenzisa, ubomi be-electrolytic capacitor kwi-inverter abuyi kudlula iminyaka emi-5, ubomi befeni yokupholisa abuyi kudlula iminyaka emi-3, ukutshintshiselana kunye nokugcinwa kufuneka kwenziwe ngaphambili.

1.Ugcino lwamandla oguqulo rhoqo

Ukonga amandla okuguqula amaza kuboniswa ikakhulu ekusetyenzisweni kwefeni kunye nempompo yamanzi.Emva kokulawulwa kwesantya sokujikeleza okuguquguqukayo samkelwe kwimithwalo yefeni kunye nempompo, izinga lokonga amandla li-20% ~ 60%, kuba olona setyenziso lwamandla ombane kunye nemithwalo yempompo lulingana nesithathu samandla esantya.Xa i-avareji yokuhamba efunwa ngabasebenzisi incinci, iifeni kunye neepompo zisebenzisa umgaqo wesantya sokuguqulwa kwesantya ukunciphisa isantya sabo, kwaye umphumo wokonga amandla ubonakala kakhulu.Ngelixa abalandeli bemveli kunye neepompo zisebenzisa ii-baffles kunye neevalvu kulawulo lokuhamba, isantya semoto asitshintshanga, kwaye ukusetyenziswa kwamandla kuyatshintsha kancinci.Ngokwezibalo, ukusetyenziswa kwamandla e-fan kunye ne-pump motors kubalelwa kwi-31% yokusetyenziswa kwamandla esizwe kunye ne-50% yokusetyenziswa kwamandla kwimizi-mveliso.Kubaluleke kakhulu ukusebenzisa isixhobo solawulo lwesantya soguqulo kumthwalo onjalo.Okwangoku, ezona zicelo zibe nempumelelo ngakumbi zibandakanya unikezelo lwamanzi olucinezelekileyo, ulawulo oluguquguqukayo lwesantya seefeni ezahlukeneyo, izifudumezi zomoya ezisembindini kunye neempompo zehydraulic.

2.Ugcino lwamandla olonga rhoqo

Ukonga amandla okuguqula amaza kuboniswa ikakhulu ekusetyenzisweni kwefeni kunye nempompo yamanzi.Emva kokulawulwa kwesantya sokujikeleza okuguquguqukayo samkelwe kwimithwalo yefeni kunye nempompo, izinga lokonga amandla li-20% ~ 60%, kuba olona setyenziso lwamandla ombane kunye nemithwalo yempompo lulingana nesithathu samandla esantya.Xa i-avareji yokuhamba efunwa ngabasebenzisi incinci, iifeni kunye neepompo zisebenzisa umgaqo wesantya sokuguqulwa kwesantya ukunciphisa isantya sabo, kwaye umphumo wokonga amandla ubonakala kakhulu.Ngelixa abalandeli bemveli kunye neepompo zisebenzisa ii-baffles kunye neevalvu kulawulo lokuhamba, isantya semoto asitshintshanga, kwaye ukusetyenziswa kwamandla kuyatshintsha kancinci.Ngokwezibalo, ukusetyenziswa kwamandla e-fan kunye ne-pump motors kubalelwa kwi-31% yokusetyenziswa kwamandla esizwe kunye ne-50% yokusetyenziswa kwamandla kwimizi-mveliso.Kubaluleke kakhulu ukusebenzisa isixhobo solawulo lwesantya soguqulo kumthwalo onjalo.Okwangoku, ezona zicelo zibe nempumelelo ngakumbi zibandakanya unikezelo lwamanzi olucinezelekileyo, ulawulo oluguquguqukayo lwesantya seefeni ezahlukeneyo, izifudumezi zomoya ezisembindini kunye neempompo zehydraulic.

3.Isicelo ekuphuculeni umgangatho wenkqubo kunye nomgangatho wemveliso

Isiguquli sefrikhwensi sinokusetyenziswa ngokubanzi kwiindawo ezahlukeneyo zolawulo lwezixhobo zoomatshini ezinjengokuhambisa, ukuphakamisa, ukukhupha kunye nezixhobo zoomatshini.Inokuphucula umgangatho wenkqubo kunye nomgangatho wemveliso, ukunciphisa impembelelo kunye nengxolo yezixhobo, kunye nokwandisa ubomi benkonzo yezixhobo.Emva kokwamkela ulawulo lwesantya sokuguqulwa kwesantya, inkqubo yoomatshini yenziwa lula, kwaye ukusebenza kunye nokulawula kulula ngakumbi.Abanye banokude batshintshe iinkcukacha zenkqubo yokuqala, ngaloo ndlela bephucula umsebenzi wesixhobo sonke.Umzekelo, kumatshini welaphu kunye nokulinganisa osetyenziswa kumashishini amaninzi, iqondo lobushushu ngaphakathi kumatshini lihlengahlengiswa ngokutshintsha ubungakanani bomoya oshushu.I-fan ejikelezayo idla ngokusetyenziselwa ukuhambisa umoya oshushu.Ekubeni isantya se-fan sihlala sihlala, isixa somoya oshushu otyiswayo sinokuhlengahlengiswa kuphela yi-damper.Ukuba i-damper ihluleka ukulungelelanisa okanye ukulungiswa ngokungafanelekanga, umatshini wokubumba uya kulahlekelwa ukulawula, ngaloo ndlela uchaphazela umgangatho weemveliso ezigqityiweyo.I-fan ejikelezayo iqala ngesantya esiphezulu, kwaye ukunxiba phakathi kwebhanti yokuqhuba kunye nokuthwala kunzima kakhulu, okwenza ibhanti yokuqhuba ibe yinto esetyenziswayo.Emva kokuba umgaqo wesantya sokuguqulwa kwamaza wamkelwe, ummiselo wobushushu unokuqondwa sisiguquli esijikelezayo ukulungelelanisa ngokuzenzekelayo isantya sefeni, esisombulula ingxaki yomgangatho wemveliso.Ukongeza, i-frequency converter inokuqalisa ngokulula i-fan kwi-frequency ephantsi kunye nesantya esisezantsi, ukunciphisa ukunxiba phakathi kwebhanti yokuqhuba kunye nokuthwala, ukwandisa ubomi benkonzo yesixhobo, kwaye ugcine amandla ngama-40%.

4.Ukuphunyezwa kwesiqalo esithambileyo semoto

Ukuqala kanzima kwemoto akuyi kubangela impembelelo enzulu kuphela kwigridi yamandla, kodwa kuya kufuna umthamo omkhulu wegridi yamandla.Umsinga omkhulu kunye nokungcangcazela okuveliswe ngexesha lokuqalisa kuya kubangela umonakalo omkhulu kwii-baffles kunye neevalvu, kwaye kuya kuba yingozi kakhulu kubomi benkonzo yezixhobo kunye nemibhobho.Emva kokusebenzisa i-inverter, umsebenzi wokuqalisa othambileyo we-inverter uya kwenza utshintsho lwangoku oluqalayo ukusuka kwi-zero, kwaye ixabiso eliphezulu aliyi kudlula umlinganiselo wangoku, ukunciphisa impembelelo kwigridi yamandla kunye neemfuno zokunikezelwa kwamandla, ukwandisa inkonzo. ubomi bezixhobo kunye neevalvu, kunye nokugcina iindleko zokugcinwa kwezixhobo

Inkcazo

Uhlobo lombane: 380V kunye ne220V
Umthamo weMotor esebenzayo: 0.75kW ukuya kuma-315kW
Iinkcukacha jonga kwiThebhile1

I-Voltage Umzekelo No. Umthamo olinganisiweyo (kVA) Isiphumo esikalisiweyo sangoku (A) Injini esebenzayo (kW)
380V
isigaba sesithathu
I-RDI67-0.75G-A3 1.5 2.3 0.75
I-RDI67-1.5G-A3 3.7 3.7 1.5
I-RDI67-2.2G-A3 4.7 5.0 2.2
I-RDI67-4G-A3 6.1 8.5 4.0
RDI67-5.5G/7.5P-A3 11 13 5.5
I-RDI67-7.5G/11P-A3 14 17 7.5
I-RDI67-11G/15P-A3 21 25 11
RDI67-15G/18.5P-A3 26 33 15
I-RDI67-18.5G/22P-A3 31 39 18.5
I-RDI67-22G/30P-A3 37 45 22
I-RDI67-30G/37P-A3 50 60 30
RDI67-37G/45P-A3 61 75 37
RDI67-45G/55P-A3 73 90 45
RDI67-55G/75P-A3 98 110 55
RDI67-75G/90P-A3 130 150 75
RDI67-93G/110P-A3 170 176 90
I-RDI67-110G/132P-A3 138 210 110
I-RDI67-132G/160P-A3 167 250 132
I-RDI67-160G/185P-A3 230 310 160
RDI67-200G/220P-A3 250 380 200
I-RDI67-220G-A3 258 415 220
I-RDI67-250G-A3 340 475 245
I-RDI67-280G-A3 450 510 280
I-RDI67-315G-A3 460 605 315
220V
isigaba esinye
I-RDI67-0.75G-A3 1.4 4.0 0.75
I-RDI67-1.5G-A3 2.6 7.0 1.2
I-RDI67-2.2G-A3 3.8 10.0 2.2

Isigaba esisodwa se-220V series

Injini esebenzayo (kW) Umzekelo No. Umzobo Ubungakanani: (mm)
220 uthotho A B C G H ibholithi yokufaka
0.75~2.2 0.75 kW ~ 2.2kW Isazobe 2 125 171 165 112 160 M4

Izigaba ezithathu380V series

Injini esebenzayo (kW) Umzekelo No. Umzobo Ubungakanani: (mm)
220 uthotho A B C G H ibholithi yokufaka
0.75~2.2 0.75kW ~ 2.2kW Isazobe 2 125 171 165 112 160 M4
4 4kW 150 220 175 138 208 M5
5.5~7.5 5.5kW ~ 7.5kW 217 300 215 205 288 M6
11 11kW Isazobe sesi-3 230 370 215 140 360 M8
15–22 15kW ~ 22kW 255 440 240 200 420 M10
30–37 30kW ~ 37kW 315 570 260 230 550
45~55 45kW ~ 55kW 320 580 310 240 555
75~93 75kW~93kW 430 685 365 260 655
110-132 110kW ~ 132kW 490 810 360 325 785
160-200 160kW ~ 200kW 600 900 355 435 870
220 200kW ~ 250kW Fig4 710 1700 410 Ukufakwa kwekhabhathi yokufika
250
280 280kW ~ 400kW 800 1900 420
315

2 3 4

Inkangeleko kunye nokunyuka komlinganiselo

Ubungakanani bemilo bona iFig2, Fig3, Fig4, ubume bemeko yokusebenza bona Fig1

3 4

1.Ugcino lwamandla oguqulo rhoqo

Ukonga amandla okuguqula amaza kuboniswa ikakhulu ekusetyenzisweni kwefeni kunye nempompo yamanzi.Emva kokulawulwa kwesantya sokujikeleza okuguquguqukayo samkelwe kwimithwalo yefeni kunye nempompo, izinga lokonga amandla li-20% ~ 60%, kuba olona setyenziso lwamandla ombane kunye nemithwalo yempompo lulingana nesithathu samandla esantya.Xa i-avareji yokuhamba efunwa ngabasebenzisi incinci, iifeni kunye neepompo zisebenzisa umgaqo wesantya sokuguqulwa kwesantya ukunciphisa isantya sabo, kwaye umphumo wokonga amandla ubonakala kakhulu.Ngelixa abalandeli bemveli kunye neepompo zisebenzisa ii-baffles kunye neevalvu kulawulo lokuhamba, isantya semoto asitshintshanga, kwaye ukusetyenziswa kwamandla kuyatshintsha kancinci.Ngokwezibalo, ukusetyenziswa kwamandla e-fan kunye ne-pump motors kubalelwa kwi-31% yokusetyenziswa kwamandla esizwe kunye ne-50% yokusetyenziswa kwamandla kwimizi-mveliso.Kubaluleke kakhulu ukusebenzisa isixhobo solawulo lwesantya soguqulo kumthwalo onjalo.Okwangoku, ezona zicelo zibe nempumelelo ngakumbi zibandakanya unikezelo lwamanzi olucinezelekileyo, ulawulo oluguquguqukayo lwesantya seefeni ezahlukeneyo, izifudumezi zomoya ezisembindini kunye neempompo zehydraulic.

2.Ugcino lwamandla olonga rhoqo

Ukonga amandla okuguqula amaza kuboniswa ikakhulu ekusetyenzisweni kwefeni kunye nempompo yamanzi.Emva kokulawulwa kwesantya sokujikeleza okuguquguqukayo samkelwe kwimithwalo yefeni kunye nempompo, izinga lokonga amandla li-20% ~ 60%, kuba olona setyenziso lwamandla ombane kunye nemithwalo yempompo lulingana nesithathu samandla esantya.Xa i-avareji yokuhamba efunwa ngabasebenzisi incinci, iifeni kunye neepompo zisebenzisa umgaqo wesantya sokuguqulwa kwesantya ukunciphisa isantya sabo, kwaye umphumo wokonga amandla ubonakala kakhulu.Ngelixa abalandeli bemveli kunye neepompo zisebenzisa ii-baffles kunye neevalvu kulawulo lokuhamba, isantya semoto asitshintshanga, kwaye ukusetyenziswa kwamandla kuyatshintsha kancinci.Ngokwezibalo, ukusetyenziswa kwamandla e-fan kunye ne-pump motors kubalelwa kwi-31% yokusetyenziswa kwamandla esizwe kunye ne-50% yokusetyenziswa kwamandla kwimizi-mveliso.Kubaluleke kakhulu ukusebenzisa isixhobo solawulo lwesantya soguqulo kumthwalo onjalo.Okwangoku, ezona zicelo zibe nempumelelo ngakumbi zibandakanya unikezelo lwamanzi olucinezelekileyo, ulawulo oluguquguqukayo lwesantya seefeni ezahlukeneyo, izifudumezi zomoya ezisembindini kunye neempompo zehydraulic.

3.Isicelo ekuphuculeni umgangatho wenkqubo kunye nomgangatho wemveliso

Isiguquli sefrikhwensi sinokusetyenziswa ngokubanzi kwiindawo ezahlukeneyo zolawulo lwezixhobo zoomatshini ezinjengokuhambisa, ukuphakamisa, ukukhupha kunye nezixhobo zoomatshini.Inokuphucula umgangatho wenkqubo kunye nomgangatho wemveliso, ukunciphisa impembelelo kunye nengxolo yezixhobo, kunye nokwandisa ubomi benkonzo yezixhobo.Emva kokwamkela ulawulo lwesantya sokuguqulwa kwesantya, inkqubo yoomatshini yenziwa lula, kwaye ukusebenza kunye nokulawula kulula ngakumbi.Abanye banokude batshintshe iinkcukacha zenkqubo yokuqala, ngaloo ndlela bephucula umsebenzi wesixhobo sonke.Umzekelo, kumatshini welaphu kunye nokulinganisa osetyenziswa kumashishini amaninzi, iqondo lobushushu ngaphakathi kumatshini lihlengahlengiswa ngokutshintsha ubungakanani bomoya oshushu.I-fan ejikelezayo idla ngokusetyenziselwa ukuhambisa umoya oshushu.Ekubeni isantya se-fan sihlala sihlala, isixa somoya oshushu otyiswayo sinokuhlengahlengiswa kuphela yi-damper.Ukuba i-damper ihluleka ukulungelelanisa okanye ukulungiswa ngokungafanelekanga, umatshini wokubumba uya kulahlekelwa ukulawula, ngaloo ndlela uchaphazela umgangatho weemveliso ezigqityiweyo.I-fan ejikelezayo iqala ngesantya esiphezulu, kwaye ukunxiba phakathi kwebhanti yokuqhuba kunye nokuthwala kunzima kakhulu, okwenza ibhanti yokuqhuba ibe yinto esetyenziswayo.Emva kokuba umgaqo wesantya sokuguqulwa kwamaza wamkelwe, ummiselo wobushushu unokuqondwa sisiguquli esijikelezayo ukulungelelanisa ngokuzenzekelayo isantya sefeni, esisombulula ingxaki yomgangatho wemveliso.Ukongeza, i-frequency converter inokuqalisa ngokulula i-fan kwi-frequency ephantsi kunye nesantya esisezantsi, ukunciphisa ukunxiba phakathi kwebhanti yokuqhuba kunye nokuthwala, ukwandisa ubomi benkonzo yesixhobo, kwaye ugcine amandla ngama-40%.

4.Ukuphunyezwa kwesiqalo esithambileyo semoto

Ukuqala kanzima kwemoto akuyi kubangela impembelelo enzulu kuphela kwigridi yamandla, kodwa kuya kufuna umthamo omkhulu wegridi yamandla.Umsinga omkhulu kunye nokungcangcazela okuveliswe ngexesha lokuqalisa kuya kubangela umonakalo omkhulu kwii-baffles kunye neevalvu, kwaye kuya kuba yingozi kakhulu kubomi benkonzo yezixhobo kunye nemibhobho.Emva kokusebenzisa i-inverter, umsebenzi wokuqalisa othambileyo we-inverter uya kwenza utshintsho lwangoku oluqalayo ukusuka kwi-zero, kwaye ixabiso eliphezulu aliyi kudlula umlinganiselo wangoku, ukunciphisa impembelelo kwigridi yamandla kunye neemfuno zokunikezelwa kwamandla, ukwandisa inkonzo. ubomi bezixhobo kunye neevalvu, kunye nokugcina iindleko zokugcinwa kwezixhobo

Inkcazo

Uhlobo lombane: 380V kunye ne220V
Umthamo weMotor esebenzayo: 0.75kW ukuya kuma-315kW
Iinkcukacha jonga kwiThebhile1

I-Voltage Umzekelo No. Umthamo olinganisiweyo (kVA) Isiphumo esikalisiweyo sangoku (A) Injini esebenzayo (kW)
380V
isigaba sesithathu
I-RDI67-0.75G-A3 1.5 2.3 0.75
I-RDI67-1.5G-A3 3.7 3.7 1.5
I-RDI67-2.2G-A3 4.7 5.0 2.2
I-RDI67-4G-A3 6.1 8.5 4.0
RDI67-5.5G/7.5P-A3 11 13 5.5
I-RDI67-7.5G/11P-A3 14 17 7.5
I-RDI67-11G/15P-A3 21 25 11
RDI67-15G/18.5P-A3 26 33 15
I-RDI67-18.5G/22P-A3 31 39 18.5
I-RDI67-22G/30P-A3 37 45 22
I-RDI67-30G/37P-A3 50 60 30
RDI67-37G/45P-A3 61 75 37
RDI67-45G/55P-A3 73 90 45
RDI67-55G/75P-A3 98 110 55
RDI67-75G/90P-A3 130 150 75
RDI67-93G/110P-A3 170 176 90
I-RDI67-110G/132P-A3 138 210 110
I-RDI67-132G/160P-A3 167 250 132
I-RDI67-160G/185P-A3 230 310 160
RDI67-200G/220P-A3 250 380 200
I-RDI67-220G-A3 258 415 220
I-RDI67-250G-A3 340 475 245
I-RDI67-280G-A3 450 510 280
I-RDI67-315G-A3 460 605 315
220V
isigaba esinye
I-RDI67-0.75G-A3 1.4 4.0 0.75
I-RDI67-1.5G-A3 2.6 7.0 1.2
I-RDI67-2.2G-A3 3.8 10.0 2.2

Isigaba esisodwa se-220V series

Injini esebenzayo (kW) Umzekelo No. Umzobo Ubungakanani: (mm)
220 uthotho A B C G H ibholithi yokufaka
0.75~2.2 0.75 kW ~ 2.2kW Isazobe 2 125 171 165 112 160 M4

Izigaba ezithathu380V series

Injini esebenzayo (kW) Umzekelo No. Umzobo Ubungakanani: (mm)
220 uthotho A B C G H ibholithi yokufaka
0.75~2.2 0.75kW ~ 2.2kW Isazobe 2 125 171 165 112 160 M4
4 4kW 150 220 175 138 208 M5
5.5~7.5 5.5kW ~ 7.5kW 217 300 215 205 288 M6
11 11kW Isazobe sesi-3 230 370 215 140 360 M8
15–22 15kW ~ 22kW 255 440 240 200 420 M10
30–37 30kW ~ 37kW 315 570 260 230 550
45~55 45kW ~ 55kW 320 580 310 240 555
75~93 75kW~93kW 430 685 365 260 655
110-132 110kW ~ 132kW 490 810 360 325 785
160-200 160kW ~ 200kW 600 900 355 435 870
220 200kW ~ 250kW Fig4 710 1700 410 Ukufakwa kwekhabhathi yokufika
250
280 280kW ~ 400kW 800 1900 420
315

2 3 4

Inkangeleko kunye nokunyuka komlinganiselo

Ubungakanani bemilo bona iFig2, Fig3, Fig4, ubume bemeko yokusebenza bona Fig1

3 4

Iindidi zeemveliso

Bhala umyalezo wakho apha kwaye uwuthumele kuthi