Xav txog kev tiv thaiv kev phom sij li lub bouncer ntawm ib hmos. Nws tsuas yog tso qee tus neeg nyob hauv thiab nrawm cov neeg tsim txom sai. Tau txais ntau nthuav? Zoo, ib qho zoo tag nrho lub tsev tiv thaiv kev tiv thaiv hluav taws xob tiv thaiv tsis ua qhov qub. Nws tso cai rau hauv hluav taws xob uas koj lub tsev xav tau thiab tsis yog qhov tsis tsub hla dhau ntawm cov nqi hluav taws xob - tom qab ntawd nws tiv thaiv koj cov cuab yeej ntawm cov teeb meem uas yuav tshwm sim los ntawm kev npau taws nyob sab hauv tsev. Tag nrho cov khoom siv tiv thaiv hluav taws xob thaiv tsev (SPDs) feem ntau yog txuas rau lub thawv hluav taws xob thiab nyob ze kom tiv thaiv tag nrho cov khoom siv hluav taws xob thiab hluav taws xob hauv tsev.

80 feem pua ​​ntawm surges hauv tsev uas peb tsim peb tus kheej.

Zoo li ntau ntawm cov tshuaj tiv thaiv kev phom sij, peb tau siv rau, cov neeg tiv thaiv hluav taws xob thoob plaws tsev siv hlau oxide varistors (MOVs), kom tsis txhob muaj hluav taws xob surges. MOVs tau txais kev phom sij phem vim tias hauv kev txhawb nqa mob ib pob zuj zus tuaj yeem xaus qhov kev muaj txiaj ntsig ntawm MOV. Tab sis tsis zoo li cov uas siv nyob rau hauv feem ntau cov kab ke loj, cov hauv cov tsev kaw lus tag nrho tau tsim los ua qhov tsis txaus siab loj thiab tuaj yeem siv sijhawm ntau xyoo. Raws li cov kws tshaj lij, muaj cov neeg tsim kho vaj tsev ntau niaj hnub no muaj kev tiv thaiv thoob plaws lub tsev yog cov qauv ntxiv los pab cov tub ntxhais sib txawv thiab pab tiv thaiv cov tswv tsev kev nqis peev hauv cov hluav taws xob hluav taws xob - tshwj xeeb tshaj yog qee qhov ntawm cov rhiab no tuaj yeem muag los ntawm tus tsim tsev.

Nov yog 5 yam koj yuav tsum paub txog kev tiv thaiv tsev ib leeg:

1. Cov tsev xav tau ntau qhov kev pab tiv thaiv tsev thoob plaws hnub no dua li tam sim no.

Peb tus kws tshaj lij hais tias "Muaj ntau qhov hloov hauv tsev ob peb xyoos dhau los," tus kws tshaj lij hais tias. "Muaj ntau ntau cov khoom siv hluav taws xob, thiab txawm tias nyob rau hauv cov teeb pom kev zoo nrog LEDs, yog tias koj coj LED sib nrug nws muaj me ntsis Circuit Court board nyob ntawd. Cov tshuab ntxhua khaub ncaws, tshuab ziab khaub ncaws, khoom siv tseem muaj cov kab hluav taws xob niaj hnub no, yog li niaj hnub no muaj kev tiv thaiv ntau hauv tsev los ntawm kev siv hluav taws xob - txawm tias lub tsev teeb pom kev zoo. "Muaj ntau thev naus laus zis uas peb tab tom ntsaws rau peb lub tsev."

2. Xob laim tsis yog qhov txaus ntshai tshaj plaws rau cov khoom siv hluav taws xob thiab lwm lub tsev hauv tsev.

Tus kws tshaj lij hais "Feem ntau cov neeg xav txog surges li xob laim, tab sis 80 feem pua ​​ntawm surges yog qhov pib [luv, tawg heev], thiab peb tsim lawv tus kheej," tus kws tshaj lij hais. "Lawv nyob sab hauv tsev." Cov tshuab hluav taws xob thiab cov tshuab cua zoo li cov uas nyob hauv cov tshuab cua txias thiab cov cuab yeej siv coj los qhia me me rau cov tsev hluav taws xob. Pluemer piav qhia "Nws yog qhov tsis tshua muaj kev cuam tshuam loj uas yuav tshem tawm cov khoom siv thiab txhua yam nyob rau hauv ib zaug," tab sis cov kev tawm tswv yim me me nyob rau xyoo yuav ntxiv, txo qis kev ua haujlwm ntawm cov khoom siv hluav taws xob thiab txiav luv luv lawv cov kev siv lub neej.

3. Tag nrho kev tiv thaiv tsev kom tiv thaiv lwm cov khoom siv hluav taws xob.

Koj tuaj yeem nug, "Yog tias qhov teeb meem feem ntau nyob hauv tsev tau los ntawm cov tshuab xws li AC units thiab cov cuab yeej siv, vim li cas thiaj thab tag nrho kev tiv thaiv tsev thoob plaws ntawm lub vaj huam sib luag?” Cov lus teb yog tias cov khoom siv lossis lub zog ua haujlwm ntawm lub Circuit Court tshwj xeeb, zoo li lub tshuab cua txias, yuav xa cov suab nrov rov qab los ntawm lub vaj huam sib luag, qhov chaw nws tuaj yeem ua kom tiv thaiv txhua yam hauv tsev, tus kws tshaj lij hais tias.

4. Tag nrho cov txheej txheem kev tiv thaiv tsev yuav tsum muab txheej.

Yog tias cov khoom siv los yog cov khoom siv xa tawm ntawm cov hluav taws xob dhau ntawm lub xov hluav taws xob uas tau sib koom nrog lwm cov khoom siv thiab tsis mob siab, ces lwm qhov chaw tawm hluav taws xob tuaj yeem ua rau raug mob hnyav, uas yog vim li cas koj tsis xav tau nws tsuas yog ntawm hluav taws xob. Kev tiv thaiv kev nyab xeeb yuav tsum tau muab fawm kem hauv tsev kom muaj ob qho tib si ntawm qhov kev pabcuam hluav taws xob tiv thaiv tag nrho tsev thiab ntawm qhov siv los tiv thaiv cov khoom siv hluav taws xob. Lub tshuab hluav taws xob muaj lub zog ua kom muaj peev xwm, nrog rau kev muaj peev xwm los muab lub zog rau cov khoom siv suab / yees duab, pom zoo rau ntau yam kev ua yeeb yam hauv tsev thiab kev lom zem hauv tsev.

5. Dab tsi yuav tsum saib rau hauv tag nrho cov tsev tiv thaiv kab ke tiv thaiv.

Yuav luag txhua lub tsev nrog 120-volt pabcuam tuaj yeem tiv thaiv kev tiv thaiv zoo nrog 80kA-rated surge tiv thaiv. Txoj hauv kev yog ib lub tsev tsis yog mus rau pom loj loj ntawm 50kA rau 100kA. Txawm hais tias lub teeb hluav taws xob nyob ze ntawm kev hla mus los ntawm cov xaim hluav taws xob yuav ploj mus thaum lub tsev loj tsawv mus txog. Ib lub tsev yuav zoo li yuav tsis pom muaj qhov tshaj li 10kA. Txawm li cas los xij, 10kA ted rated ntaus ntawv tau txais 10kA kev txhawb nqa, piv txwv li, tuaj yeem siv nws qhov kev hloov pauv MOV ntawm lub peev xwm nrog qhov kev tshaj tawm ntawd, yog li ib yam dab tsi hauv 80kA kev txiav txim yuav ua kom nws siv sijhawm ntev dua. Cov tsev nrog subpanels yuav tsum tau ntxiv kev tiv thaiv ntawm kwv yees li ib nrab kA qhov ntsuas ntawm lub tsev loj. Yog tias muaj ntau qhov hluav taws xob nyob hauv ib cheeb tsam lossis yog tias muaj ib lub tsev siv cov tshuab loj nyob ze, nrhiav kev ntsuas 80kA.

Lub luag haujlwm tswj hwm kev tso cai tso cai rau kev tswj hwm kev lag luam thiab cov chaw tsim khoom hluav taws xob kom tswj tau thaum lub nra yog ntxiv lossis tso los ntawm lub zog, ua rau cov kab sib luag muaj zog dua thiab txhim kho lub zog kom ua haujlwm zoo rau cov haujlwm tseem ceeb ntawm ntau lub tshuab fais fab. Hauv daim foos yooj yim tshaj plaws, kev tswj hwm kev thauj khoom, tseem hu ua load ntxiv / tso lossis tswj kev tswj hwm, tso cai rau kev tshem tawm ntawm cov tsis tseem ceeb thaum lub peev xwm ntawm lub hwj huam mov txo lossis tsis tuaj yeem txhawb nqa tag nrho lub nra.

Nws tso cai rau koj los txiav txim siab thaum lub thauj khoom yuav tsum nqis los yog ntxiv dua

Yog tias qhov tsis yog qhov hnyav tau raug tshem tawm, cov teeb meem tseem ceeb tuaj yeem khaws lub zog nyob rau qhov xwm txheej uas lawv tsis tuaj yeem ua lub zog tsis zoo vim muaj kev ua haujlwm dhau lossis poob lub zog vim muaj kev tiv thaiv ntawm lub zog. Nws tso cai rau kev tshem tawm cov tsis hnyav los ntawm lub zog hluav taws xob tsim raws li qee yam kev mob xws li lub tshuab hluav taws xob ntau dhau qhov teeb meem.

Kev tswj cov khoom thauj khoom siv thauj khoom yuav tsum tau tsim kho ua ntej thiab tshem tawm lossis ntxiv, raws qee yam kev mob xws li lub tshuab hluav taws xob, cov zis hluav taws xob, lossis AC zaus. Ntawm lub tshuab hluav taws xob ntau, yog tias ib lub tshuab hluav taws xob kaw los yog tsis muaj, kev tswj kev thauj khoom txo qis cov khoom siv qis dua kom raug txiav tawm ntawm lub npav.

Nws txhim kho hluav taws xob zoo thiab kom ntseeg tau tias txhua qhov thauj khoom ua haujlwm

Qhov no ua kom ntseeg tau tias cov kev sib tw tseem ceeb tseem ua haujlwm txawm tias lub kaw lus uas muaj lub zog tag nrho qis dua qhov tau npaj tseg. Ib qho ntxiv, los ntawm kev tswj hwm seb muaj pes tsawg thiab uas tsis yog lub nra tsis hnyav, kev tswj hwm kev thauj khoom tuaj yeem ua kom muaj qhov ntau ntawm qhov tsis tseem ceeb rau kev xa khoom nrog lub zog raws li qhov tseeb ntawm lub peev xwm. Hauv ntau lub tshuab, thauj khoom siv kuj tseem tuaj yeem txhim kho lub zog.

Piv txwv li, hauv cov kab ke nrog cov motors loj, qhov pib ntawm lub cev muaj zog tuaj yeem raug tso cia kom tso cai rau kev ua haujlwm ruaj khov raws li txhua lub zog pib. Kev tswj hwm kev thauj khoom tuaj yeem siv ntxiv los tswj hwm lub txhab nyiaj yog li thaum cov khoom ntim qis dua qhov xav tau ntawm lub txhab nyiaj yuav tuaj yeem ua haujlwm, kom ntseeg tau tias kev ua haujlwm ntawm lub tshuab hluav taws xob.

Kev tswj hwm kev thauj khoom kuj tseem tuaj yeem muab cov kev pabcuam thauj khoom kom lub tshuab hluav taws xob nkaus xwb tuaj yeem txuas mus rau lub npav tsis thas thauj khoom sai. Kev thauj khoom tuaj yeem muab ntxiv maj mam, nrog lub sijhawm qeeb ntawm kev ntxiv txhua qhov yuav tsum tau ua dhau los, ua kom lub tshuab hluav taws xob rov qab qhov voltage thiab zaus ntawm cov kauj ruam.

Muaj ntau qhov xwm txheej uas kev tswj hwm load tuaj yeem txhim kho qhov kev cia siab ntawm lub zog hluav taws xob. Ob peb daim ntawv thov qhov twg siv thauj khoom tswj hwm yuav muab los siv raws li qhia hauv qab no.

• Cov kab ke sib txig sib luag
• Tuag-teb paralleling system
• Lub tshuab hluav taws xob ib leeg
• Cov tshuab nrog cov pa roj carbon tshwj xeeb

Cov kab ke sib txig sib luag

Yuav luag txhua qhov kev sib txig sib luag tau siv rau qee hom kev tswj hwm kev thauj khoom vim hais tias lub nra yuav tsum energized los ntawm ib lub tshuab hluav taws xob ua ntej lwm tus tuaj yeem synchronize rau nws thiab ntxiv rau lub zog tsim hluav taws xob muaj peev xwm. Ntxiv mus, lub tshuab hluav taws xob ib zaug no tuaj yeem tsis tuaj yeem xa lub zog hluav taws xob ntawm tag nrho cov ntsaws.

Cov kab ke sib txig sib luag yuav pib txhua lub tshuab hluav taws xob ib txhij, tab sis lawv tsis muaj peev xwm sib txuas ua ke rau ib leeg yam tsis muaj ib qho ntawm lawv lub zog siv lub tsheb npav uas tig mus. Ib lub tshuab hluav taws xob tau raug xaiv los ua lub zog caij tsheb npav kom lwm tus tuaj yeem synchronize rau nws. Txawm hais tias feem ntau lub tshuab hluav taws xob feem ntau sib xws thiab txuas nrog lub tsheb sib txuas hauv ob peb vib nas this ntawm thawj lub tshuab hluav taws xob kaw, nws tsis yooj yim rau cov txheej txheem synchronization yuav siv sijhawm ntev li ib feeb, ntev txaus rau ib qho dhau mus ua rau lub tshuab hluav taws xob kaw rau tiv thaiv nws tus kheej.

Lwm lub tshuab hluav taws xob tuaj yeem kaw rau lub tsheb npav tuag tom qab ntawd lub tshuab hluav taws xob kaw, tab sis lawv yuav muaj tib lub teeb meem uas ua rau lwm lub tshuab hluav taws xob dhau lawm, yog li lawv yuav coj cwj pwm zoo ib yam (tshwj tsis yog cov tshuab hluav taws xob sib txawv). Tsis tas li ntawd, nws yuav nyuaj rau cov tshuab hluav taws xob los sib txuas ua ke rau qhov chaw tos tsheb loj dhau los vim muaj qhov tsis xws luag voltage thiab ntau zaus lossis qhov hloov pauv thiab hloov mus hloov pauv hloov pauv, yog li kev koom ua ke ntawm cov kev tswj hwm yuav pab coj cov tshuab hluav taws xob ntxiv tau sai dua.

Muab lub zog zoo rau cov khoom hnyav

Kev tswj hwm txoj kev thauj khoom kom zoo yuav ib txwm muab lub zog zoo rau cov haujlwm tseem ceeb thaum kev sib koom tes los ntawm kev ua kom paub tseeb tias cov tshuab hluav taws xob online tsis dhau, txawm tias cov txheej txheem synchronizing siv sijhawm ntev dua li kev cia siab. Kev tswj hwm kev thauj khoom yuav raug ua tiav los ntawm ntau txoj kev. Cov kab ke tsis sib thooj feem ntau tswj tau los ntawm cov kab hluav taws xob hloov pauv mus txuas ntxiv, cov kab hluav taws xob txuas hloov pauv no feem ntau muaj qhov programmable logic tswj (PLC) lossis lwm cov khoom siv cav uas tswj cov kev ua haujlwm ntawm lub kaw lus. Cov cuab yeej siv cav hauv kev sib hloov switchgear kuj tseem tuaj yeem ua lub luag haujlwm tswj hwm.

Kev tswj hwm kev thauj khoom yuav ua tau los ntawm kev sib cais thauj khoom tswj hwm, uas yuav muab cov metering lossis yuav siv cov ntaub ntawv los ntawm cov khoom siv hloov mus sib xyaw kom txiav txim siab lub tshuab hluav taws xob thauj khoom thiab zaus. Ib lub tsev tswj kev ua haujlwm kuj tseem tuaj yeem ua cov kev tswj hwm ua haujlwm, tswj lub nra hnyav los ntawm kev tswj hwm kev tswj hwm thiab tshem tawm qhov xav tau ntawm cov pob hluav taws xob los cuam tshuam lub zog rau lawv.

Tuag-teb paralleling system

Tuag-teb thaum uas tig mus sib txawv los ntawm cov kab sib txig sib luag hauv txhua lub tshuab hluav taws xob tuaj yeem ua tiav ua ntej lawv lub tshuab hluav taws xob ntsuas hluav taws xob thiab lub tshuab ua teb tau zoo siab.

Yog tias txhua lub tshuab hluav taws xob hauv qhov chaw tua hluav taws xob sib xyaw pib ib txwm, lub zog tua hluav taws xob nce mus txog ntawm qhov ntsuas hluav taws xob thiab qhov zaus nrog lub zog hluav taws xob muaj peev xwm txaus los muab lub nra. Vim hais tias cov qub tuag-teb paralleling sib lawv liag tsis xav tau ib lub tshuab hluav taws xob ib leeg rau energize lub tsheb thauj mus paralleling, kev tswj hwm kev thauj khoom yuav tsum tsis tas yuav thauj khoom thaum lub zog qub.

Txawm li cas los xij, xws li cov qauv kev sib txig sib luag, qhov pib thiab nres ntawm ib tus neeg siv lub tshuab hluav taws xob yog tau nrog kev tuag-teb txoj kev sib txig. Yog tias lub tshuab hluav taws xob qis rau cov kev pabcuam lossis nres rau lwm qhov laj thawj, lwm lub tshuab hluav taws xob tseem yuav ua haujlwm dhau. Yog li, kev tswj hwm load kuj tseem yuav pab tau rau hauv cov ntawv thov no, zoo ib yam li cov qauv sib law liag.

Tuag-teb paralleling feem ntau yog ua los ntawm cov kab hluav taws xob uas muaj peev xwm sib law liag, tab sis kuj tuaj yeem ua tau los ntawm kev sib txig hloov sib npaug. Lub tshuab hluav taws xob sib xyaw ua ke feem ntau muab cov kev tswj xyuas hauv lub zog, tso cai rau cov kev thauj khoom yuav tsum tau tswj ncaj qha los ntawm cov tswj hwm thiab tshem tawm qhov xav tau ntawm cov khoom siv hloov mus sib ntxiv.

Ib Lub Cav Hluav Taws Xob

Ib lub tshuab hluav taws xob feem ntau tsis tshua muaj sib txawv dua li lawv cov kev sib tw. Cov tshuab hluav taws xob no yuav siv cov kev tswj hwm hauv lub tshuab hluav taws xob tswj kom tswj cov khoom thauj thaum raug cuam tshuam rau cov khoom thauj lossis cov kev hloov pauv hloov.

Ib qho sib dhos thauj khoom - xws li chillers, induction ncu thiab tshuab nqa - tsis kos lub zog txuas mus ntxiv, tab sis tuaj yeem sib txawv ntawm cov fais fab kev xav tau sai thiab tseem ceeb. Kev tswj hwm kev thauj khoom tuaj yeem muaj txiaj ntsig zoo nyob rau hauv cov xwm txheej uas lub tshuab hluav taws xob muaj peev xwm tuav tau ib qho kev ua haujlwm tsis tu ncua, tab sis nyob rau qee qhov xwm txheej tsis sib xws yuav ua rau kom tag nrho cov teeb tsa ntawm lub zog siab tshaj qhov siab tshaj qhov muaj peev xwm ntawm lub tshuab hluav taws xob, qhov uas ua rau lub zog tsis zoo ntawm lub tshuab hluav taws xob lossis ntxias ib qho kev tiv thaiv zoo. Kev tswj cov kev thauj khoom kuj tseem tuaj yeem siv los kaw daim ntawv thov ntawm cov nra rau lub tshuab hluav taws xob, txo qhov tsawg ntawm qhov voltage thiab zaus hloov los ntawm cov inrush mus rau lub cev muaj zog loj.

Kev tswj hwm kev thauj khoom kuj tseem yuav siv tau yog tias cov lis dej num hauv cheeb tsam xav tau chav tswj xyuas lub chaw rau cov tshuab uas cov tshuab ntsuas hluav taws xob tso tawm tam sim no tsawg dua cov kev pabcuam nkag nkag tam sim no.

Tshuab Nrog Cov Kev Xav Tau Tshwj Xeeb

Hauv qee thaj chaw, muaj qhov yuav tsum tau ua tsawg kawg rau lub tshuab hluav taws xob txhua lub sijhawm nws ua haujlwm. Hauv qhov xwm txheej no, kev tswj hwm kev thauj khoom yuav siv los ua kom lub nra ntawm lub tshuab hluav taws xob los pab ua kom tau raws li cov pa hluav taws xob. Rau daim ntawv thov no, lub tshuab hluav taws xob tsim hluav taws xob tau haum nrog lub ntsaws tswj kev tswj tau. Kev tswj hwm lub nruab zog tau teeb tsa lub zog ua ke rau ntau lub nra hauv lub txhab nyiaj kom tswj hwm lub tshuab hluav taws xob tso zis tawm hluav taws xob sab saud ib qho.

Qee lub tshuab hluav taws xob suav nrog Diesel Particulate Lim (DPF), uas yuav tsum tau tsim dua tshiab. Qee qhov xwm txheej, lub cav yuav ua kom 50% ntawm lub zog ntsuas thaum nres nres ntawm DPF, thiab tuaj yeem siv zog tswj hwm kev tswj hwm kom tshem tawm qee qhov thau khoom thaum muaj mob.

Txawm hais tias kev tswj hwm lub zog tuaj yeem txhim kho lub zog kom zoo rau cov haujlwm tseem ceeb hauv cov kab ke, nws yuav ntxiv qhov qeeb ua ntej qee lub ntim tau txais lub zog, ua kom muaj qhov nyuaj ntawm kev teeb tsa thiab ntxiv qhov tseem ceeb ntawm cov kev siv dag zog nrog rau cov nqi ntawm cov khoom, xws li cov neeg ua haujlwm lossis cov hluav taws xob. Cov. Qee cov ntawv thov uas qhov kev tswj hwm thauj khoom yuav tsis tsim nyog sau tseg hauv qab no.

Cov Khoom Siv Tsim Kho Kom Zoo Tshaj

Feem ntau tsis tas yuav muaj lub luag haujlwm thauj khoom siv rau ntawm lub tshuab hluav taws xob kom zoo, raws li kev ua haujlwm ntau dhau qhov tsis zoo, thiab lub tshuab hluav taws xob yuav ua rau tag nrho cov teeb meem poob hwj chim, tsis hais qhov muaj feem thib.

Paaj Txheeb Ze Cov Hluav Taws Xob rau Kev Ua Kom Rov Qab

Kev tswj cov load feem ntau tsis tsim nyog nyob rau hauv cov xwm txheej uas muaj cov hluav taws xob sib txig sib luag thiab qhov chaw ntawm lub zog yuav tsum tau txais kev txhawb nqa los ntawm ib qho ntawm lub tshuab hluav taws xob, vim tias lub tshuab hluav taws xob tsis ua haujlwm tsuas yog ua rau lwm lub tshuab hluav taws xob pib, nrog kev cuam tshuam ib ntus hauv lub luag haujlwm.

Txhua Qhov Kev Thauj Khoom yog sib npaug Qhov Kev Xav

Ntawm cov chaw uas txhua qhov teeb meem yog sib npaug, nws nyuaj rau qhov tseem ceeb ua ntej, tshem tawm qee qhov tseem ceeb rau kev txhawm rau txuas ntxiv muab lub zog rau lwm cov nra hnyav. Nyob rau hauv daim ntawv thov no, lub tshuab hluav taws xob (lossis txhua lub tshuab hluav taws xob hauv qhov rov qhib dua) yuav tsum tsim nyog kom loj los txhawb tag nrho lub nra tseem ceeb.

Kev puas tsuaj los ntawm cov khoom siv hluav taws xob hloov, lossis surges, yog ib qho ua rau cov khoom siv hluav taws xob tsis ua haujlwm. Kev hloov pauv hluav taws xob yog lub sijhawm luv luv, lub zog hluav taws xob siab uas muab rau ntawm cov hluav taws xob hluav taws xob li qub thaum twg muaj kev hloov pauv tam sim ntawd ntawm lub tshuab hluav taws xob. Lawv tuaj yeem pib los ntawm ntau yam khoom siv, ob sab hauv thiab sab nraud mus rau qhov chaw.

Tsis yog xob laim xwb

Qhov pom tseeb tshaj plaws yog los ntawm xob laim, tab sis surges tseem tuaj yeem los ntawm cov khoom siv hluav taws xob hloov mus ua haujlwm lossis cov teeb meem hluav taws xob tsis ceev faj (xws li thaum lub tshuab hluav taws xob sab saum toj poob rau hauv av). Cov kev nce siab yuav tuaj yeem yog los ntawm ib lub tsev lossis qhov chaw los ntawm cov khoom xws li fax machine, tshuab luam ntawv, tshuab ntsuas cua txias, tshuab nqa lub tshuab, lub cav tsheb / lub twj tso kua mis, lossis arc welders, rau npe ob peb tug. Hauv txhua kis, hluav taws xob hluav taws xob ib txwm pom tam sim ntawd rau lub zog ntau ntawm lub zog uas tuaj yeem cuam tshuam rau cov cuab yeej siv hluav taws xob.

Cov hauv qab no yog cov txheej txheem tiv thaiv hluav taws xob txog kev tiv thaiv cov cuab yeej hluav taws xob los ntawm kev puas tsuaj ntawm kev cuam tshuam hluav taws xob siab. Kev tiv thaiv zoo uas yog qhov loj me thiab teeb tsa tau zoo heev hauv kev tiv thaiv cov khoom ua kom puas, tshwj xeeb tshaj yog rau cov khoom siv hluav taws xob uas pom muaj nyob hauv cov cuab yeej siv niaj hnub no.

Av yog qhov pib

Lub tshuab tiv thaiv hluav taws xob tiv thaiv (SPD), tseem hu ua cov khoom siv hluav taws xob tsis hloov pauv (TVSS), yog tsim los hloov cov kev siv hluav taws xob ntxiv rau hauv av thiab dhau ntawm koj cov cuab yeej, thiaj li txwv cov hluav taws xob tsis zoo rau cov khoom siv. Vim li no, nws tseem ceeb tias koj lub tsev muaj qhov ua tau zoo, muaj kev tiv thaiv qis, nrog rau ib qho chaw hais txog ntawm thaj chaw ntawm txhua lub tsev txuas nrog.

Yog tias tsis muaj qhov kev tiv thaiv zoo, tsis muaj txoj hauv kev los tiv thaiv kev surges. Sab laj nrog cov tsim hluav taws xob muaj ntawv tso cai kom ntseeg tau tias koj cov hluav taws xob faib hluav taws xob tau ua tiav raws li Lub Tebchaws Txoj Cai Hluav Taws Xob (NFPA 70).

Cov chaw ntawm kev tiv thaiv

Qhov kev txhais tau zoo tshaj plaws ntawm kev tiv thaiv koj cov cuab yeej hluav taws xob los ntawm kev siv hluav taws xob ntau yog los tsim SPDs cov tswv yim thoob plaws koj qhov chaw. Xav tias kev cia siab tuaj yeem yog los ntawm ob qhov los sab hauv thiab sab nraud, SPDs yuav tsum muab ntsia kom muaj kev tiv thaiv siab tshaj plaws tsis hais lub hauv paus ntawm chaw. Vim li no, txoj haujlwm "Thaj Chaw Tiv Thaiv" feem ntau yog ua haujlwm.

Thawj theem ntawm kev tiv thaiv yog ua tiav los ntawm kev txhim kho SPD rau ntawm cov kev pabcuam nkag loj (piv txwv li, qhov chaw siv hluav taws xob los rau hauv lub chaw). Qhov no yuav muab kev tiv thaiv tawm tsam kev siv zog los ntawm sab nraud, xws li xob laim lossis hluav taws xob hloov chaw.

Txawm li cas los xij, SPD nruab rau ntawm cov kev pabcuam nkag yuav tsis tiv thaiv kev tiv thaiv sab hauv. Tsis tas li ntawd, tsis yog txhua lub zog los ntawm sab nraud surges yog dissipated mus rau hauv av los ntawm kev pabcuam nkag khoom. Vim li no, SPDs yuav tsum tau nruab rau txhua lub tshuab faib khoom siv hauv chaw ua haujlwm uas muab lub zog rau cov khoom siv tseem ceeb.

Ib yam li ntawd, peb ntu kev tiv thaiv yuav ua tiav los ntawm kev txhim kho SPD nyob rau hauv zos rau txhua daim ntawm cov khoom siv tiv thaiv, xws li khoos phis tawj lossis lub koos pij tawj tswj hwm. Txhua cheeb tsam ntawm kev tiv thaiv ntxiv rau tag nrho kev tiv thaiv ntawm lub chaw vim txhua qhov pab ntxiv qhov txo cov hluav taws xob raug rau cov cuab yeej tiv thaiv.

Kev Saib Xyuas ntawm SPDs

Qhov kev pabcuam nkag nkag mus SPD muab thawj kab kev tiv thaiv tiv thaiv hluav taws xob hloov chaw rau qhov chaw kho mob los ntawm diverting siab zog, sab nraud surges rau hauv av. Nws tseem txo qis zog ntawm lub zog nce ntawm qhov chaw mus rau qhov chaw mus rau theem uas tuaj yeem kho los ntawm cov cuab yeej hauv nruab nrog qis dua los ntawm lub nra. Yog li, kev sib koom tes tsim nyog ntawm SPDs yog yuav tsum tau zam kom tsis txhob ua kom cov SPDs raug teeb tsa rau ntawm cov chaw faib khoom lossis hauv thaj chaw ntawm cov khoom siv tsis zoo.

Yog tias kev sib koom tes tsis tiav, lub zog ntau dhau los ntawm kev nthuav dav yuav ua rau thaj tsam 2 thiab Thaj Chaw 3 SPD ua kom puas thiab ua kom puas cov khoom siv uas koj xav ua los tiv thaiv.

Xaiv cov khoom phim rau Kev Tiv Thaiv Sab Nraud (SPD) tuaj yeem zoo li ua haujlwm tsis txaus ntseeg nrog txhua yam sib txawv ntawm cov khw muag khoom niaj hnub no. Qhov kev ntsuas neeg nce siab lossis kA qhov ntsuas ntawm SPD yog ib qho ntawm cov neeg tsis to taub txog. Cov neeg yuav khoom ib txwm thov rau SPD tiv thaiv lawv 200 Amp pawg vaj huam sib luag thiab muaj lub siab xav tias lub vaj huam sib luag loj dua, qhov loj dua ntawm kA ntaus ntawv xav tau yuav tsum muaj kev tiv thaiv tab sis qhov no yog qhov kev nkag siab yuam kev.

Thaum tus kws khomob nkag mus hauv lub vaj huam sib luag, nws tsis quav ntsej lossis paub qhov loj me ntawm lub vaj huam sib luag. Yog li koj yuav paub tau li cas yog tias koj yuav tsum siv 50kA, 100kA lossis 200kA SPD? Tiag tiag, qhov kev phais loj tshaj plaws uas tuaj yeem nkag mus rau hauv lub tsev cov hlua hlau yog 10kA, raws li tau piav qhia hauv IEEE C62.41 tus qauv. Yog li vim li cas koj thiaj li yuav xav tau SPD ntsuas rau 200kA? Cias teev - rau kev thiav.

Yog li ib tug yuav xav: yog tias 200kA zoo, ces 600kA yuav tsum yog peb zaug zoo dua, txoj cai? Tsis tsim nyog. Ntawm qee kis, qhov kev ntaus nqi ploj zuj zus rov qab, tsuas yog ntxiv cov nqi ntxiv thiab tsis muaj txiaj ntsig zoo. Txij li feem ntau SPDs ntawm kev ua lag luam siv cov hlau oxide varistor (MOV) ua lub cuab yeej tseem ceeb, peb tuaj yeem tshawb xyuas seb vim li cas / vim li cas kA kev tshaj tawm tau tiav. Yog tias MOV yog nyob rau 10kA thiab pom qhov ua tau li 10kA, nws yuav siv 100% ntawm nws lub peev xwm. Qhov no tuaj yeem saib me ntsis zoo li lub taub roj av, qhov twg cov phais yuav thuam cov MOV ntau dua me ntsis (tsis ntev nws yog 100% tag nrho). Tam sim no yog tias SPD muaj ob lub 10kA MOVs hauv lub mus tib seem, nws yuav raug ntsuas rau 20kA.

Raws li txoj kev xav, cov MOVs yuav muab faib kom sib txawv li 10kA kev nce, yog li txhua tus yuav siv sij hawm 5kA. Hauv qhov xwm txheej no, txhua MOV tsuas tau siv 50% ntawm lawv lub peev xwm uas ua rau MOV hloov tsawg dua (tso ntau rau hauv lub taub dej pov tseg rau yav tom ntej).

Thaum xaiv SPD rau cov ntawv thov, muaj ob peb cov kev txiav txim siab uas yuav tsum tau ua:

daim ntawv thov:

Ua kom ntseeg tau tias SPD tau tsim rau cheeb tsam ntawm kev tiv thaiv uas nws yuav siv. Piv txwv li, SPD ntawm qhov kev pabcuam nkag yuav tsum tsim los daws cov kev loj dua uas tshwm sim los ntawm xob laim lossis hluav taws xob hloov.

System voltage thiab teeb tsa

SPDs tau tsim los rau cov qib hluav taws xob tshwj xeeb thiab cov teeb tsa hauv Circuit Court. Piv txwv li, koj cov kev pabcuam nkag khoom siv tuaj yeem nkag mus rau peb-theem lub zog ntawm 480/277 V hauv plaub-hlau xov txuas txuas, tab sis lub tshuab computer hauv cheeb tsam tau nruab rau ib-theem, 120 V muab lus.

Cia-dhau ntawm qhov voltage

Qhov no yog qhov hluav taws xob uas SPD yuav tso cai rau cov khoom tiv thaiv kom raug tiv thaiv. Txawm li cas los xij, muaj kev puas tsuaj rau cov khoom siv yog nyob ntawm seb cov khoom siv tau ntev npaum li cas raug rau qhov no cia-dhau ntawm voltage hauv kev sib piv nrog cov khoom tsim qauv. Hauv lwm cov lus, cov khoom siv feem ntau tsim los tiv qhov ntsuas qhov hluav taws xob siab rau lub sijhawm luv luv thiab txo qis hluav taws xob rau lub sijhawm ntev dua.

Tsoom Fwv Cov Ntaub Ntawv Qhia Txog Kev Ua Haujlwm (FIPS) kev tshaj tawm "Cov Lus Qhia rau Lub Hluav Taws Xob Hluav Taws Xob rau Kev Siv Ntaub Ntawv Nruab Nrab Tsis Siv Hluav Taws Xob" (FIPS Pub. DU294) qhia cov ntsiab lus ntawm kev sib txuas ntawm clamping voltage, system voltage, thiab lub sijhawm ntev.

Raws li qhov ua piv txwv, qhov hloov ntawm kab xaum 480 V uas kav txog 20 microseconds tuaj yeem nce mus txog yuav luag 3400V yam tsis muaj cov khoom siv tsis zoo uas tsim los rau cov lus qhia no. Tab sis ib qho kev thauj ntawm ib puag ncig 2300 V tuaj yeem ua tiav rau 100 microseconds tsis tas yuav ua kev puas tsuaj. Feem ntau hais lus, qis qis clamp voltage, qhov kev tiv thaiv zoo dua.

Surge tam sim no

SPDs raug ntsuas kom muaj kev nyab xeeb pauj ib qho ntawm cov txiaj ntsig tam sim no yam tsis poob. Qhov kev ntsuas no muaj nqis txij li ob peb txhiab amps txog 400 kiloamperes (kA) lossis ntau dua. Txawm li cas los xij, qhov tam sim no qhov nruab nrab ntawm kev tiv thaiv xob laim tsuas yog kwv yees li 20 kA., Nrog qhov ntsuas ntau tshaj tam sim no tsuas yog tshaj 200 kA. Xob laim uas ntaus hluav taws xob tua yuav ua rau ob sab, yog li ib nrab tam sim no mus rau koj lub chaw haujlwm. Raws txoj kev, qee qhov tam sim no yuav ploj mus rau hauv av los ntawm cov cuab yeej hluav taws xob.

Yog li ntawd, muaj peev xwm tam sim no ntawm qhov kev pabcuam nkag los ntawm kev tawm tsam hluav taws xob sab nraud yog qhov chaw ze 10 kA. Ntxiv rau, qee qhov chaw ntawm lub tebchaws yog cov nquag muaj xob laim dua li lwm tus. Tag nrho cov xwm txheej no yuav tsum raug txiav txim siab thaum txiav txim siab seb qhov luaj li cas SPD tsim nyog rau koj daim ntawv thov.

Txawm li cas los xij, nws yog ib qho tseem ceeb uas yuav tau txiav txim siab hais tias ib qho SPD ntsuas ntawm 20 kA yuav muaj peev xwm tiv thaiv tau zoo los ntawm qhov nruab nrab ntawm xob laim ntaus tawm thiab feem ntau sab hauv tsim tawm sab nraud ib zaug, tab sis ib qho SPD uas tau ntsuas 100 kA yuav tuaj yeem kho ntxiv surges tsis tas yuav hloov tus raug ntes lossis fuses.

Standards

Txhua SPD yuav tsum raug kuaj raws li ANSI / IEEE C62.41 thiab tau teev rau UL 1449 (Thib 2) kom muaj kev nyab xeeb.

Underwriters Laboratories (UL) yuav tsum muaj qee qhov cim yuav tsum muaj nyob rau ntawm UL cov ntawv teev tseg lossis raug lees paub SPD. Qee qhov ntsuas uas tseem ceeb thiab yuav tsum raug txiav txim siab thaum xaiv SPD suav nrog:

SPD Hom

siv los piav qhia cov chaw thov SPD, ib qho dej ntws tawm sab saud los yog nqes dej ntawm cov twj thaiv kev tiv thaiv ntawm lub chaw ua haujlwm. Hom SPD muaj xws li:

ntaus 1

Chaw txuas nrog tas mus li SPD npaj rau nruab nruab nrab ntawm cov theem nrab ntawm cov kev pabcuam hloov pauv thiab cov kab sab ntawm cov kev pabcuam cov khoom siv ua haujlwm tshaj dhau cov khoom siv, nrog rau cov thauj khoom sab, suav nrog lub vauj vais vais-xaim txuas nrog lub qhov rooj thiab Moulded Case SPDs, npaj los ntsia tsis muaj cov khoom siv tiv thaiv sab nraud sab nraud.

ntaus 2

SPD txuas nrog mus tas li npaj rau nruab ntawm cov chaw thau khoom ntawm cov kev pabcuam cov khoom siv thauj khoom siv, suav nrog SPDs nyob rau ntawm cov ceg ntoo thiab Moulded Case SPDs.

ntaus 3

Taw tes ntawm kev siv SPDs, ntsia ntawm qhov tsawg kawg yog tus kav ntev ntev 10 metres (30 ko taw) los ntawm lub rooj tsav xwm kev pabcuam hluav taws xob mus rau qhov kev siv, piv txwv li, txuas nrog, txuas ntsaws ncaj qha, hom kev tiv thaiv SPDs ntsia ntawm cov cuab yeej siv hluav taws xob tiv thaiv. Cov. Qhov deb (10 meters) tsuas yog tshwj xeeb ntawm cov neeg xyuas pib muab nrog lossis siv los txuas cov SPDs.

ntaus 4

Lub Rooj Sib Tham Sib Tham -, Cov Txheej Txheem Lub Rooj Sib Tham uas muaj ib lossis ntau hom 5 yam ua ke nrog qhov tsis sib txuas (sab hauv lossis sab nraud) lossis txhais tau tias ua tau raws li cov kev ntsuas tam sim no.

Hom 1, 2, 3 Txheej Txheem Sib Tham

Muaj hom 4 cov khoom sib dhos ua ke nrog kev tiv thaiv sab hauv lossis sab nraud luv luv.

ntaus 5

Kev faib tawm cov khoom pov tseg kom zoo ntxiv, xws li MOVs uas yuav raug teeb tsa ntawm PWB, txuas nrog los ntawm nws cov coj lossis muab nyob rau hauv ib qho chaw thaiv nrog cov txhais tau tias tso zis thiab cov lus xov txuas.

Nominal system qhov hluav taws xob

Yuav tsum sib phim cov nqi hluav taws xob system qhov twg los ntawm cov khoom siv

MCOV

Qhov Kev Ua Haujlwm Ntau Nrho Cov Hluav Taws Xob, qhov no yog qhov ntsuas hluav taws xob ntau tshaj plaws uas lub cuab yeej tuaj yeem tiv thaiv ua ntej pib sib dhos (clamping) pib. Nws yog feem ntau 15-25% siab dua li ntawm qhov system nominal voltage.

Lub Neej Tsis Txaus tam sim no (I_n)

Yog tus nqi siab kawg ntawm tam sim no, dhau ntawm SPD muaj ib nthwv dej tam sim no ntawm 8/20 qhov chaw uas SPD tseem ua haujlwm tom qab 15 surges. Tus nqi siab tshaj yog xaiv los ntawm cov chaw tsim khoom los ntawm qib qhia UL tau teev tseg. Kuv (n) theem suav nrog 3kA, 5kA, 10kA thiab 20kA thiab kuj tseem yuav txwv los ntawm Hom SPD raws li ntsuas.

VPR

Kev Ntsuas Kev tiv thaiv tus ntsuas hluav taws xob. Kev ntsuas ib qhov ntsuas ntawm qhov hloov kho tshiab ntawm ANSI / UL 1449, taw qhia qhov "sib npaug" nruab nrab ntsuas qhov ntsuas ntawm qhov hluav taws xob ntawm SPD thaum SPD raug rau cov khoom tsim hluav taws xob tsim los ntawm 6 kV, 3 kA 8/20 combinations sib xyaw waveform tshuab hluav taws xob. VPR yog clamping voltage ntsuas uas tau sib npaug li ib ntawm cov txheej txheem ntawm cov lus. Cov kev ntsuas tus qauv VPR suav nrog 330, 400, 500, 600, 700, thiab lwm yam Raws li cov txheej txheem kev ntsuas, VPR tso cai sib piv ncaj qha ntawm SPDs (piv txwv li tib hom thiab Voltage).

SCCR

Luv Circuit Court Kev Ntsuas Tam Sim No. Qhov tsim nyog ntawm SPD rau siv rau ntawm AC hluav taws xob Circuit Court uas muaj peev xwm xa tsis tshaj li ib qho kev tshaj tawm RMS tam sim no ntawm kev tshaj tawm voltage thaum lub sijhawm luv Circuit Court. SCCR tsis zoo ib yam li AIC (Amp Kev Muaj Peev Xwm Cuam Tshuam). SCCR yog tus nqi ntawm "muaj" tam sim no uas SPD tuaj yeem raug thiab muaj kev nyab xeeb nyob rau ntawm lub zog hluav taws xob hauv cov hluav taws xob luv. Qhov tam sim no "cuam tshuam" los ntawm SPD yog feem ntau tsawg dua li "muaj" tam sim no.

Daim ntawv ntsuas kev ntaus nqi

Ua kom ntseeg tau tias NEMA kev ntsuas qhov ntsuas ntawm qhov ntim ntaws phim cov teeb meem ib puag ncig ntawm qhov chaw ntawm cov cuab yeej yuav raug teeb tsa.

Txawm hais tias feem ntau siv los ua cov lus sib cais nyob rau hauv kev lag luam surge, Hloov thiab surges yog qhov tshwm sim zoo ib yam. Cov neeg hloov pauv thiab kub siab tuaj yeem yog qhov tam sim no, voltage, lossis ob qho tib si thiab tuaj yeem muaj cov txiaj ntsig siab kawg hauv kev dhau 10kA lossis 10kV. Lawv feem ntau yog lub sijhawm luv heev (feem ntau> 10 µs & <1 ms), nrog nthwv dej uas muaj qhov nrawm nrawm mus rau qhov kawg thiab tom qab ntawd ntog tawm ntawm ntau qeeb qeeb.

Cov neeg sawv cev thiab maj nrawm tuaj yeem tshwm sim los ntawm cov khoom siv sab nraud xws li xob laim lossis luv Circuit Court, lossis los ntawm qhov chaw sab hauv xws li Tus Tawm Hloov Txuas, Tus Cuam Tshuam Ceev, Capacitor hloov, thiab lwm yam.

Kev rho tawm ib ntus (TOV) yog kev oscillatory

Ntu-rau-av lossis theem-rau-theem overvoltages uas tuaj yeem siv sijhawm me me li ob peb feeb lossis ntev li ntev li ob peb feeb. Cov khoom siv ntawm TOV's suav nrog kev ua txhaum, suav hloov chaw, thawb hauv av, cuam tshuam rau ib leeg, cov kev ua txhaum thiab cov nyom ua kom muaj npe.

Vim tias lawv qhov teeb meem loj thiab lub sijhawm ntev, TOV's tuaj yeem cuam tshuam heev rau MOV-raws li SPD's. Qhov txuas ntxiv ntawm TOV tuaj yeem ua kev puas tsuaj mus rau SPD mus tas li thiab ua kom lub tsev tsis nyob ntev. Nco ntsoov tias thaum ANSI / UL 1449 ua kom ntseeg tau tias SPD yuav tsis tsim kom muaj kev phom sij nyob rau hauv cov xwm txheej no; SPDs feem ntau tsis yog tsim los tiv thaiv cov cuab yeej qis hauv qis los ntawm TOV xwm txheej.

cov cuab yeej siv tau yooj yim rau cov hloov pauv hauv qee hom qauv dua li lwm tus

Cov khoom siv feem ntau muab cov kab-rau-nruab nrab (LN), kab-rau-hauv av (LG), thiab kev tiv thaiv nruab nrab-rau-hauv av (NG) tiv thaiv nyob rau hauv lawv cov SPDs. Thiab qee qhov tam sim no muaj kev tiv thaiv kab-rau-kab (LL). Qhov kev sib cav yog vim tias koj tsis paub tias qhov twg yuav tshwm sim nyob hauv kev hloov pauv, muaj txhua hom qauv tiv thaiv yuav ua kom tsis muaj kev puas tsuaj tshwm sim. Txawm li cas los xij, cov cuab yeej siv yog rhiab rau cov hloov hauv qee hom qauv dua li lwm tus.

LN thiab NG hom kev tiv thaiv yog qhov pom zoo yam tsawg kawg, thaum LG hom tuaj yeem ua rau SPD ntau dua rau qhov ua tsis tau zoo. Hauv ntau kab hluav taws xob tshuab, LN txuas nrog SPD hom qauv tseem muaj kev tiv thaiv rau cov hloov hloov LL. Li no, muaj kev ntseeg siab dua, tsis tshua muaj "hom txo" SPD tiv thaiv txhua hom qauv.

Ntau hom kev tiv thaiv kab mob tiv thaiv (SPDs) yog cov khoom siv uas muaj cov lej SPD ntau nyob rau hauv ib pob. Cov "hom" kev tiv thaiv no tuaj yeem txuas LN, LL, LG, thiab NG thoob plaws peb ntu. Muaj kev tiv thaiv nyob rau hauv txhua hom muab kev tiv thaiv rau cov nra hnyav tshwj xeeb rau cov kev hloov pauv sab hauv sab hauv qhov chaw hauv av tsis yog txoj kev xav rov qab.

Hauv qee qhov kev thov xws li thov SPD ntawm qhov kev pabcuam nkag uas ob qhov nruab nrab thiab cov ntsiab lus hauv nruab nrab yog tsis muaj txiaj ntsig ntawm kev cais LN thiab LG hom, txawm li cas los xij koj mus txuas ntxiv mus rau hauv kev faib tawm thiab muaj kev sib cais los ntawm qhov sib xws NG sib luag, hom SPD NG tiv thaiv yuav muaj txiaj ntsig zoo.

Thaum lub tswv yim tsim cov khoom siv tiv thaiv hluav taws xob (SPD) nrog qhov ntsuas qhov ntsuas hluav taws xob loj dua yuav zoo dua, muab piv rau SPD zog (Joule) kev ntsuas tau yuam kev. Ntau lub suab npe khoom lag luam tsis muab cov kev ntsuas hluav taws xob ntxiv lawm. Lub zog ntsuas yog qhov tawm ntawm cov kab tam sim no, kev nce siab, thiab SPD clamping voltage.

Hauv kev sib piv ob yam khoom, qhov qis ntaus nqi yuav zoo dua yog tias qhov no ua rau cov hluav taws xob tsawg tsawg clamping, thaum lub zog hluav taws xob loj dua yuav zoo dua yog tias qhov no yog qhov txiaj ntsig loj dua tam sim no siv. Yog tsis muaj cov qauv meej rau SPD lub zog ntsuas, thiab cov tuam ntxhab tau paub kom siv cov raj ntev ntev kom muab cov txiaj ntsig loj dua kom yuam kev rau cov neeg siv kawg.

Vim tias kev tshaj tawm Joule tuaj yeem yooj yim kho tau ntau yam ntawm cov qauv kev lag luam (UL) thiab cov txheej txheem (IEEE) tsis pom zoo sib piv ntawm joules. Hloov chaw, lawv muab tso rau kev tsom mus rau qhov tseeb kev ua tau zoo ntawm SPDs nrog rau kev sim xws li Cov Nominal Kev Kho Mob Tam Sim No, uas sim SPDs kev tiv thaiv nrog rau VPR kuaj uas qhia txog qhov cia-dhau ntawm voltage. Nrog rau cov ntaub ntawv no, kev sib piv zoo dua los ntawm SPD mus rau lwm tus tuaj yeem ua tau.