Kev faib hluav taws xob: chaw nres tsheb, khoom siv tsim nyog, kev faib khoom, daim ntawv thov, accounting thiab tswj cov cai

2024 Tus sau: Howard Calhoun | [email protected]. Kawg hloov kho: 2023-12-17 10:28

Kev faib hluav taws xob thiab nws txoj kev xa tawm ntawm lub zog loj rau cov neeg siv khoom li cas? Qhov teeb meem no yog qhov nyuaj heev, txij li lub hauv paus yog substation, uas tuaj yeem nyob ntawm qhov deb ntawm lub nroog, tab sis lub zog yuav tsum tau xa nrog kev ua haujlwm siab tshaj plaws. Qhov teeb meem no yuav tsum tau txiav txim siab ntxiv.

piav qhia dav dav ntawm txheej txheem

Raws li tau hais ua ntej, thawj qhov khoom, los ntawm qhov chaw faib hluav taws xob pib, hnub no yog lub tshuab hluav taws xob. Niaj hnub no, muaj peb hom chaw nres tsheb loj uas tuaj yeem muab cov neeg siv khoom siv hluav taws xob. Nws tuaj yeem yog lub tshuab hluav taws xob thermal (TPP), lub chaw tsim hluav taws xob hluav taws xob (HPP) thiab lub chaw tsim hluav taws xob nuclear (NPP). Ntxiv rau cov hom yooj yim no, kuj tseem muaj hnub ci lossis cua noj, txawm li cas los xij cov no yog siv rau ntau lub hom phiaj hauv zos.

Peb hom chaw nres tsheb no yog qhov chaw thiab thawj qhov chaw faib hluav taws xob. RauTxhawm rau kom ua tiav cov txheej txheem xws li kev sib kis ntawm hluav taws xob hluav taws xob, nws yog ib qho tsim nyog yuav tsum tau ua kom muaj zog ntxiv. Qhov deb ntawm cov neeg siv khoom yog, qhov siab dua qhov voltage yuav tsum yog. Yog li, qhov nce tuaj yeem ncav cuag 1150 kV. Qhov kev nce ntawm qhov voltage yog qhov tsim nyog txhawm rau txhawm rau txo lub zog tam sim no. Nyob rau hauv cov ntaub ntawv no, cov kuj nyob rau hauv cov xov hlau kuj poob. Cov nyhuv no tso cai rau koj hloov tam sim no nrog lub zog tsawg kawg nkaus. Yuav kom nce qhov voltage mus rau qhov xav tau, txhua qhov chaw nres tsheb muaj ib kauj ruam-up transformer. Tom qab dhau los ntawm ntu nrog lub tshuab hloov pauv, cov hluav taws xob tam sim no raug xa mus rau qhov chaw faib khoom nruab nrab siv cov kab hluav taws xob. PIU yog lub chaw faib khoom nruab nrab uas muaj hluav taws xob faib ncaj qha.

piav qhia dav dav ntawm txoj kev tam sim no

Cov chaw xws li cov chaw faib khoom nruab nrab twb nyob ze rau cov nroog, cov zos, thiab lwm yam. Ntawm no, tsis yog tsuas yog kev faib tawm xwb, tab sis kuj muaj qhov hluav taws xob poob rau 220 lossis 110 kV. Tom qab ntawd, hluav taws xob tau xa mus rau cov chaw nres tsheb uas nyob hauv lub nroog lawm.

Thaum dhau los ntawm cov chaw me me no, qhov hluav taws xob poob dua, tab sis mus rau 6-10 kV. Tom qab ntawd, kev sib kis thiab kev faib hluav taws xob yog nqa tawm los ntawm cov ntsiab lus transformer nyob rau hauv ntau qhov chaw ntawm lub nroog. Nws tseem tsim nyog sau cia ntawm no tias kev xa tawm ntawm lub zog hauv nroog mus rau qhov chaw hloov pauv hloov pauv tsis tau ua nrog kev pab ntawm cov kab hluav taws xob, tab sis nrog kev pab los ntawm cov kab hauv av. Qhov no yog qhov tsim nyog ntau dua li kev siv cov kab hluav taws xob. Qhov taw tes transformer yog qhov chaw kawg ntawmnyob rau hauv uas qhov kev faib tawm thiab xa hluav taws xob, nrog rau kev txo qis rau lub sijhawm kawg, yuav siv qhov chaw. Nyob rau hauv xws li cov cheeb tsam, qhov voltage yog txo mus rau qhov twb paub lawm 0.4 kV, uas yog, 380 V. Ces nws yog pauv mus rau private, multi-storey tsev, garage cooperatives, thiab lwm yam.

Yog tias peb luv luv xav txog txoj kev sib kis, nws yog kwv yees li hauv qab no: lub zog qhov chaw (10 kV fais fab nroj tsuag) - kauj ruam-up transformer mus txog 110-1150 kV - fais fab kis kab - substation nrog step-down transformer - transformer point nrog voltage poob mus rau 10- 0.4 kV - cov neeg siv khoom (private sector, tsev nyob, thiab lwm yam).

txheej txheem nta

Kev tsim khoom thiab xa tawm hluav taws xob, nrog rau cov txheej txheem ntawm nws txoj kev sib kis, muaj qhov tseem ceeb - tag nrho cov txheej txheem no txuas mus ntxiv. Hauv lwm lo lus, kev tsim hluav taws xob hluav taws xob coincides nyob rau hauv lub sij hawm nrog cov txheej txheem ntawm nws noj, uas yog vim li cas lub hwj chim chaw nres tsheb, networks thiab receivers yog interconnected los ntawm xws li ib tug tswvyim raws li ib tug ntau yam hom. Cov cuab yeej no ua rau nws tsim nyog los npaj cov tshuab hluav taws xob kom ua tau zoo dua hauv kev tsim thiab xa hluav taws xob.

Ntawm no nws tseem ceeb heev kom nkag siab tias lub zog zoo li cas. Qhov no yog cov txheej txheem ntawm txhua qhov chaw nres tsheb, cov kab hluav taws xob, cov chaw nres tsheb thiab lwm cov khoom siv cua sov, uas muaj kev sib cuam tshuam los ntawm cov cuab yeej xws li ib hom kev sib txuas, nrog rau ib qho txheej txheem rau kev tsim hluav taws xob hluav taws xob. Tsis tas li ntawd, cov txheej txheem kev hloov pauv thiab kev faib tawm hauv cov cheeb tsam no tau ua raws li qhov dav davkhiav tag nrho qhov system.

Lub chaw ua haujlwm tseem ceeb hauv cov tshuab no yog kev teeb tsa hluav taws xob. Cov khoom siv no yog tsim los rau kev tsim khoom, kev hloov pauv, kev sib kis thiab kev faib hluav taws xob. Lub zog no tau txais los ntawm hluav taws xob txais. Raws li rau kev teeb tsa lawv tus kheej, nyob ntawm qhov ua haujlwm voltage, lawv tau muab faib ua ob chav kawm. Thawj qeb ua haujlwm nrog voltages txog 1000 V, thiab qhov thib ob, ntawm qhov tsis sib xws, nrog voltages ntawm 1000 V thiab siab dua.

Ntxiv rau, kuj tseem muaj cov cuab yeej tshwj xeeb rau kev txais, xa tawm thiab xa hluav taws xob - lub tshuab hloov hluav taws xob (RU). Qhov no yog ib qho hluav taws xob installation, uas muaj xws li cov yam ntxwv xws li prefabricated thiab txuas busbars, cov khoom siv rau kev hloov thiab kev tiv thaiv, automation, telemechanics, ntsuas ntsuas thiab cov cuab yeej pabcuam. Cov chav no kuj tau muab faib ua ob pawg. Thawj yog qhib cov cuab yeej uas tuaj yeem ua haujlwm sab nraum zoov, thiab kaw, uas tsuas yog siv thaum nyob hauv ib lub tsev. Raws li kev ua haujlwm ntawm cov khoom siv hauv nroog, feem ntau nws yog qhov kev xaiv thib ob uas siv.

Ib qho ntawm qhov kawg ntawm txoj kev xa hluav taws xob thiab kev faib hluav taws xob yog lub chaw nres tsheb. Qhov no yog ib yam khoom uas muaj xws li ib tug switchgear mus txog 1000 V thiab los ntawm 1000 V, nrog rau lub hwj chim transformers thiab lwm yam auxiliary units.

Kev txiav txim siab ntawm txoj kev faib hluav taws xob

Yuav ua tib zoo saib cov txheej txheem ntawm kev tsim khoom, xa tawm thiab xa tawmhluav taws xob, koj tuaj yeem ua piv txwv daim duab thaiv ntawm kev muab hluav taws xob rau lub nroog.

Nyob rau hauv cov ntaub ntawv no, cov txheej txheem pib nrog qhov tseeb hais tias cov generators ntawm lub xeev koog tsev kawm ntawv fais fab chaw nres tsheb (lub xeev regional fais fab nroj tsuag) tsim voltage ntawm 6, 10 los yog 20 kV. Nyob rau hauv lub xub ntiag ntawm xws li ib tug voltage, nws tsis yog economical xa mus rau ib tug deb ntawm ntau tshaj li 4-6 km, vim hais tias yuav muaj kev poob loj. Txhawm rau kom txo qis hluav taws xob poob, lub zog hloov hluav taws xob tau suav nrog hauv cov kab sib kis, uas yog tsim los ua kom muaj qhov hluav taws xob ntau ntxiv rau cov txiaj ntsig xws li 35, 110, 150, 220, 330, 500, 750 kV. Tus nqi raug xaiv nyob ntawm seb tus neeg siv khoom nyob deb npaum li cas. Qhov no yog ua raws li qhov taw tes rau kev txo qis hluav taws xob, uas tau nthuav tawm nyob rau hauv daim ntawv ntawm cov kauj ruam-down substation nyob rau hauv lub nroog. Qhov hluav taws xob raug txo mus rau 6-10 kV. Nws yog tsim nyog ntxiv ntawm no hais tias xws li ib tug substation muaj ob feem. Thawj feem ntawm hom qhib yog tsim los rau qhov hluav taws xob ntawm 110-220 kV. Qhov thib ob yog kaw, suav nrog cov khoom siv hluav taws xob faib hluav taws xob (RU), tsim rau qhov hluav taws xob ntawm 6-10 kV.

Txoj kev npaj hluav taws xob

Ntxiv rau cov khoom siv uas tau teev tseg ua ntej, cov khoom siv hluav taws xob kuj suav nrog cov khoom siv xws li cov khoom siv hluav taws xob xaim hluav taws xob - PKL, cov kab hluav taws xob xaim hluav taws xob - RKL, cov kab hluav taws xob muaj hluav taws xob ntawm 0.4 kV - KL, Ib hom kev hloov pauv hloov pauv hauv lub tsev nyob - ASU, lub ntsiab kauj ruam-down substation ntawm cov nroj tsuag - GPP, lub hwj chim faib txee los yog switchboardtswj vaj huam sib luag ntaus ntawv, nyob rau hauv lub khw cog, thiab tsim rau 0.4 kV.

Kuj nyob rau hauv Circuit Court tej zaum yuav muaj xws li ib feem xws li lub hwj chim center - CPU. Nws yog ib qho tseem ceeb uas yuav tsum nco ntsoov ntawm no tias cov khoom no tuaj yeem sawv cev los ntawm ob qho khoom siv sib txawv. Qhov no tej zaum yuav yog ib qho hluav taws xob hloov hluav taws xob theem nrab ntawm lub chaw ua haujlwm qis. Tsis tas li ntawd, nws tseem yuav suav nrog cov khoom siv uas yuav ua haujlwm ntawm kev tswj hwm qhov hluav taws xob thiab nws cov khoom xa tuaj tom qab rau cov neeg siv khoom. Qhov thib ob version yog transformer rau kev sib kis thiab xa hluav taws xob, lossis lub tshuab hluav taws xob hluav taws xob hloov hluav taws xob ncaj qha ntawm lub tshuab fais fab.

Nws yog ib qho tsim nyog sau cia tias CPU txuas nrog txhua lub sijhawm rau RP faib. Txoj kab uas txuas rau ob yam khoom no tsis muaj kev faib hluav taws xob raws nws qhov ntev. Cov kab no feem ntau hu ua kab kab.

Hnub no, xws li cov cuab yeej xws li KTP - lub chaw hloov pauv hloov pauv tiav - tuaj yeem siv rau hauv daim phiaj hluav taws xob. Nws muaj ob peb transformers, ib tug faib los yog input ntaus ntawv, tsim los ua hauj lwm nrog ib tug voltage ntawm 6-10 kV. Cov khoom siv kuj muaj xws li switchgear rau 0.4 kV. Tag nrho cov khoom siv no yog sib cuam tshuam los ntawm cov neeg ua haujlwm tam sim no, thiab cov khoom siv tau xa los yog npaj txhij rau kev sib dhos. Kev txais tos thiab kev faib hluav taws xob kuj tuaj yeem tshwm sim ntawm cov qauv siab lossis ntawm cov hluav taws xob xa hluav taws xob. Cov qauv no yog hu ua ncej lossis mast transformer substations.(IB).

thawj qeb hluav taws xob txais

Hnub no, muaj peb pawg ntawm cov khoom siv hluav taws xob, uas txawv ntawm qhov kev ntseeg siab.

thawj qeb ntawm cov khoom siv hluav taws xob suav nrog cov khoom, thaum lub zog tsis ua haujlwm uas muaj teeb meem loj heev. Cov tom kawg suav nrog cov hauv qab no: kev hem thawj rau tib neeg lub neej, kev puas tsuaj loj rau lub teb chaws kev lag luam, kev puas tsuaj rau cov khoom kim heev los ntawm cov pab pawg tseem ceeb, cov khoom lag luam tsis zoo, kev puas tsuaj ntawm cov txheej txheem thev naus laus zis tsim los tsim thiab xa tawm hluav taws xob, kev cuam tshuam tuaj yeem tshwm sim. hauv kev ua haujlwm ntawm cov ntsiab lus tseem ceeb ntawm kev siv pej xeem. Cov khoom siv hluav taws xob zoo li no suav nrog cov tsev uas muaj neeg coob coob, piv txwv li, lub tsev ua yeeb yam, lub tsev loj, lub khw muag khoom, thiab lwm yam. Cov pab pawg no kuj suav nrog kev thauj hluav taws xob (metro, trolleybus, tram).

Txog kev muab hluav taws xob rau cov qauv no, lawv yuav tsum tau muab hluav taws xob los ntawm ob qhov chaw uas muaj kev ywj pheej ntawm ib leeg. Kev txiav tawm ntawm lub network ntawm cov tuam tsev no tsuas yog tso cai rau lub sijhawm uas lub zog thaub qab yuav pib. Hauv lwm lo lus, lub zog xa hluav taws xob yuav tsum muab kev hloov pauv sai ntawm ib qho mus rau lwm qhov, thaum muaj xwm txheej ceev. Nyob rau hauv rooj plaub no, ib qho hluav taws xob ywj pheej yog suav tias yog ib qho ntawm qhov voltage yuav nyob twj ywm txawm tias nws ploj mus rau lwm qhov chaw uas pub tib lub tshuab txais hluav taws xob.

Thawj qeb kuj suav nrog cov khoom siv uas yuav tsum tau siv los ntawm peb qhov chaw ywj pheej ib zaug. Qhov no yog ib pab pawg tshwj xeeb uas nws txoj haujlwm yuav tsum tau ua kom tsis muaj kev cuam tshuam. Ntawd yog, kev txiav tawm ntawm lub zog hluav taws xob tsis raug tso cai txawm tias lub sijhawm thaum muaj xwm txheej ceev tau qhib. Feem ntau, cov pab pawg no suav nrog cov neeg txais, qhov ua tsis tiav uas ua rau muaj kev hem thawj rau tib neeg lub neej (kev tawg, hluav taws, thiab lwm yam).

thib ob thiab thib peb qeb txais

Cov tshuab hluav taws xob xaim hluav taws xob nrog kev sib txuas ntawm cov khoom siv hluav taws xob thib ob suav nrog cov khoom siv no, thaum lub hwj chim raug kaw, yuav muaj kev poob qis ntawm kev ua haujlwm loj thiab kev thauj mus los hauv kev lag luam, kev xa khoom ntawm cov khoom, nrog rau kev cuam tshuam. ntawm cov kev ua ub no ntawm ib tug loj tus naj npawb ntawm cov neeg nyob rau hauv ob qho tib si nyob rau hauv lub nroog, raws li zoo raws li tshaj. Cov pab pawg ntawm cov khoom siv hluav taws xob no suav nrog cov tsev nyob saum toj 4 pem teb, cov tsev kawm ntawv thiab tsev kho mob, cov chaw tsim hluav taws xob, cov hluav taws xob tsis ua haujlwm uas yuav tsis ua rau cov khoom siv kim kim, nrog rau lwm pawg ntawm cov neeg siv hluav taws xob uas muaj tag nrho cov khoom ntawm 400 rau. 10,000 kV.

Ob lub chaw nres tsheb ywj pheej yuav tsum ua raws li lub zog hauv pawg no. Tsis tas li ntawd, kev txiav tawm ntawm lub zog tseem ceeb ntawm cov chaw no tau tso cai kom txog thaum cov neeg ua haujlwm ntawm lub luag haujlwm pib qhov chaw thaub qab, lossis pab pawg neeg ua haujlwm ntawm lub chaw xa hluav taws xob ze tshaj plaws ua qhov no.

Rau rau qeb thib peb ntawm cov neeg txais, tom qab ntawd raulawv muaj tag nrho cov khoom siv ntxiv uas tuaj yeem siv tau los ntawm 1 lub zog hluav taws xob xwb. Tsis tas li ntawd, kev txiav tawm ntawm lub network ntawm cov neeg txais tau tso cai rau lub sijhawm kho lossis hloov cov khoom puas rau lub sijhawm tsis pub dhau ib hnub.

daim duab qhia txog kev muab khoom thiab kev faib hluav taws xob

Kev tswj hwm ntawm kev faib hluav taws xob thiab nws txoj kev xa tawm los ntawm qhov chaw mus rau cov neeg txais khoom ntawm qeb thib peb hauv lub nroog tau yooj yim tshaj plaws los ntawm kev siv lub phiaj xwm radial tuag-kawg. Txawm li cas los xij, cov tswv yim zoo li no muaj ib qho teeb meem tseem ceeb, uas yog tias ib qho ntawm lub cev tsis ua haujlwm, txhua tus txais kev txuas nrog cov tswv yim zoo li no yuav nyob twj ywm tsis muaj hwj chim. Qhov no yuav txuas ntxiv mus kom txog rau thaum qhov kev puas tsuaj ntawm cov saw hlau hloov. Vim qhov tsis txaus no, nws tsis pom zoo kom siv cov txheej txheem hloov pauv.

Yog tias peb tham txog kev sib txuas thiab kev faib hluav taws xob rau cov neeg txais khoom ntawm pawg thib ob thiab thib peb, ntawm no koj tuaj yeem siv daim duab kos duab ntawm lub nplhaib. Nrog rau qhov kev sib txuas zoo li no, yog tias ib qho ntawm cov kab hluav taws xob tsis ua haujlwm, koj tuaj yeem rov qab tau lub zog hluav taws xob rau txhua tus neeg txais kev sib txuas nrog lub network zoo li no hauv phau ntawv hom, yog tias koj tua lub hwj chim los ntawm qhov chaw tseem ceeb thiab pib lub thaub qab. Lub nplhaib hluav taws xob sib txawv ntawm lub voj voog radial nyob rau hauv uas nws muaj cov ntu tshwj xeeb ntawm cov disconnectors lossis cov keyboards nyob rau hauv hom tawm. Yog tias lub hauv paus fais fab puas raug puas lawm, lawv tuaj yeem muab rov qab rau cov khoom siv, tab sis los ntawm cov kab thaub qab. Nws kuj yuav pabib qho txiaj ntsig zoo yog tias kev kho yuav tsum tau nqa tawm ntawm txoj kab tseem ceeb. Kev so hauv lub zog ntawm cov kab no tau tso cai rau lub sijhawm li ob teev. Lub sijhawm no yog txaus los tua cov hluav taws xob loj uas puas lawm thiab txuas cov thaub qab mus rau lub network kom nws faib hluav taws xob.

Nws yog ib txoj hauv kev txhim khu kev qha ntau dua los txuas thiab faib hluav taws xob - qhov no yog lub tswv yim nrog kev sib txuas ntawm ob txoj kab xa khoom lossis kev qhia txog kev sib txuas tsis siv neeg ntawm qhov chaw thaub qab. Nrog rau cov tswv yim zoo li no, cov kab puas yuav raug txiav tawm los ntawm kev faib tawm dav dav siv ob lub keyboards nyob ntawm txhua qhov kawg ntawm kab. Kev muab hluav taws xob nyob rau hauv cov ntaub ntawv no yuav ua tau nyob rau hauv ib tug tseem uninterrupted hom, tab sis twb dhau los ntawm ob kab. Cov tswv yim no muaj feem cuam tshuam rau cov neeg txais ntawm qeb thib ob.

Kev faib tawm rau thawj qeb ntawm cov neeg txais

Raws li kev faib hluav taws xob rau lub zog rau cov neeg txais khoom ntawm thawj qeb, qhov no yuav tsum tau txuas los ntawm ob lub chaw tsim hluav taws xob ywj pheej tib lub sijhawm. Tsis tas li ntawd, cov tswv yim zoo li no feem ntau siv tsis yog ib qho kev faib tawm, tab sis ob, thiab ib qho kev siv hluav taws xob tsis siv neeg rov qab ib txwm muab.

Rau cov khoom siv hluav taws xob uas koom nrog thawj qeb, tsis siv neeg hloov mus rau lub zog thaub qab tau teeb tsa rau ntawm cov khoom siv nkag. Nrog xws li ib qho kev sib txuas, kev faib hluav taws xob tam sim noyog ua los ntawm kev siv ob txoj kab hluav taws xob, txhua tus uas muaj qhov ntsuas hluav taws xob txog li 1 kV, thiab tseem txuas nrog cov hloov hluav taws xob ywj pheej.

Lwm tus txais kev faib khoom thiab lub zog hluav taws xob

Txhawm rau kom muaj txiaj ntsig zoo tshaj plaws faib hluav taws xob rau cov neeg txais thib ob, koj tuaj yeem siv lub voj voog nrog kev tiv thaiv overcurrent rau ib lossis ob lub RPs, nrog rau lub voj voog nrog lub zog thaub qab tsis siv neeg. Txawm li cas los xij, muaj qee qhov yuav tsum tau muaj ntawm no. Cov tswv yim no tuaj yeem siv tau tsuas yog yog tias tus nqi ntawm cov khoom siv rau lawv qhov kev npaj tsis nce ntau dua 5%, piv nrog rau kev hloov pauv ntawm phau ntawv hloov mus rau lub zog thaub qab. Tsis tas li ntawd, nws yog ib qho tsim nyog yuav tsum tau muab cov ntu zoo li no los ntawm txoj kab uas ib kab tuaj yeem nqa cov khoom thauj los ntawm qhov thib ob, suav nrog lub sijhawm luv luv. Qhov no yog qhov tsim nyog, vim tias yog ib qho tsis ua tiav, qhov kev faib tawm ntawm txhua qhov hluav taws xob yuav raug xa mus rau qhov seem.

Muaj ib txoj kab ncaj nraim txuas thiab faib cov phiaj xwm. Hauv qhov no, ib qho chaw faib khoom yuav raug siv los ntawm ob qhov sib txawv transformers. Ib lub cable txuas nrog rau txhua tus ntawm lawv, qhov hluav taws xob tsis tshaj 1000 V. Txhua lub tshuab hloov pauv kuj tau nruab nrog ib tus contactor, uas yog tsim los hloov cov load ntawm ib lub hwj chim mus rau lwm qhov, yog tias muaj ib qho ntawm lawv. voltage yuav ploj mus.

Summing txog kev ntseeg siab ntawm lub network, qhov no yog ib qho tseem ceeb tshaj plaws uas yuav tsum tau ua.xyuas kom meej tias kev faib hluav taws xob tsis cuam tshuam. Txhawm rau kom ua tiav qhov kev ntseeg siab tshaj plaws, nws yog qhov tsim nyog tsis yog siv cov txheej txheem khoom tsim nyog tshaj plaws rau txhua pawg. Nws tseem yog ib qho tseem ceeb uas yuav tau xaiv cov hom ntawm cov cables, nrog rau lawv cov thickness thiab hla ntu, coj mus rau hauv tus account lawv cov cua sov thiab lub zog poob thaum lub sij hawm ntws ntawm tam sim no. Nws tseem yog ib qho tseem ceeb kom ua raws li cov kev cai ntawm kev ua haujlwm thiab kev siv thev naus laus zis rau kev ua haujlwm ntawm hluav taws xob tag nrho.

Raws li cov lus saum toj no, peb tuaj yeem txiav txim siab tias cov khoom siv rau kev txais thiab xa hluav taws xob, nrog rau kev muab los ntawm qhov chaw mus rau cov neeg siv khoom kawg lossis tus txais, tsis yog txheej txheem nyuaj.