Opomnik specializiranih dobaviteljev frekvenčnih pretvornikov v dvižni industriji: Frekvenčni pretvorniki za žerjave so naprave za krmiljenje moči, ki uporabljajo tehnologijo pretvorbe frekvence in mikroelektronsko tehnologijo za krmiljenje izmeničnih motorjev s spreminjanjem frekvence delovnega napajanja motorja. Frekvenčni pretvornik je sestavljen predvsem iz usmerjevalne enote (AC v DC), filtracije, inverzije (DC v AC), zavorne enote, pogonske enote, detekcijske enote, mikroprocesorske enote itd. Frekvenčni pretvornik, ki ga trenutno uporabljamo, v glavnem uporablja metodo AC-DC-AC, ki najprej pretvori izmenično napajanje omrežne frekvence v enosmerno napajanje prek usmernika, nato pa enosmerno napajanje pretvori v izmenično napajanje z nadzorovano frekvenco in napetostjo za napajanje.
1. Pri izbiri frekvenčnega pretvornika je treba določiti naslednje točke:
1) Cilj uporabe frekvenčne pretvorbe; krmiljenje konstantnega tlaka ali krmiljenje konstantnega toka itd.
2) Pri uporabi frekvenčnega pretvornika za pogon visokohitrostnega motorja dodajanje višjih harmonikov poveča vrednost izhodnega toka zaradi majhne reaktance visokohitrostnega motorja. Pri izbiri frekvenčnega pretvornika za visokohitrostne motorje ima Wuxi Qide Electrical Machinery Co., Ltd. nekoliko večjo zmogljivost kot izbira običajnih motorjev.
3) Težava z usklajevanjem med frekvenčnim pretvornikom in obremenitvijo;
I. Usklajevanje napetosti; Dodatna napetost frekvenčnega pretvornika se ujema z dodatno napetostjo bremena.
II. Usklajevanje toka; Pri običajni centrifugalni črpalki se dodatni tok frekvenčnega pretvornika ujema z dodatnim tokom motorja. Pri izrednih obremenitvah, kot so globokomorske črpalke, je treba za določitev toka in preobremenitve pretvornika na podlagi maksimalnega toka upoštevati parametre delovanja motorja.
III. Usklajevanje navora; Do te situacije lahko pride pri konstantni obremenitvi z navorom ali pri vgradnji z zaviranjem.
4) Vrsta obremenitve frekvenčnega pretvornika; Pri črpalkah, kot so krilne črpalke ali volumetrične črpalke, je treba posebno pozornost nameniti funkcionalni krivulji obremenitve, ki določa način uporabe.
5) Glede nekaterih izrednih scenarijev uporabe, kot so visoke temperature in velike nadmorske višine, lahko to povzroči zmanjšanje zmogljivosti frekvenčnega pretvornika, zato je treba zmogljivost frekvenčnega pretvornika povečati za eno prestavo.
6) If the frequency converter needs to operate with a long cable, measures should be taken to suppress the impact of the long cable on the ground coupling capacitance and prevent a lack of output from the frequency converter. Therefore, in such a situation, the capacity of the frequency converter should be expanded by one level or an output reactor should be installed at the output end of the frequency converter.
2、 Precautions for frequency converters at high temperatures
The general environmental requirements for frequency converters are: minimum ambient temperature of -5 ℃, maximum ambient temperature of 40 ℃. There is research indicating that the failure rate of frequency converters increases exponentially with temperature, while the service life decreases exponentially with temperature. When the ambient temperature increases by 10 degrees, the service life of frequency converters will be halved. Summer is a season of frequent frequency converter problems. To ensure that the frequency converter can work stably and reliably for a long time, the key is to protect and maintain it regularly.
1. Carefully monitor and record all display parameters on the human-machine interface of the frequency converter, and promptly report any abnormalities.
2. When the temperature is high in summer, it is necessary to strengthen the ventilation and heat dissipation of the installation site of the frequency converter. Ensure that the surrounding air does not contain excessive dust, acids, salts, corrosive and explosive gases.
3. During normal operation of the frequency converter, a standard thickness A4 paper should be able to firmly adhere to the filter screen at the cabinet door inlet.
4. The ventilation and lighting in the frequency conversion room must be good, and the ventilation and heat dissipation equipment (air conditioning, ventilation fans, etc.) must be able to operate normally.
5. The filter screen on the door of the inverter cabinet should usually be cleaned once a week; If there is a lot of dust in the working environment, the cleaning interval should be shortened according to the actual situation.
6. Carefully monitor and record the ambient temperature of the frequency conversion room, which should be between -5 ℃ and 40 ℃. The temperature rise of the phase-shifting transformer cannot exceed 130 ℃.
7. The frequency conversion room must be kept clean and tidy, and should be cleaned at any time according to the actual situation on site.
8. Summer is a rainy season, so it is important to prevent rainwater from entering the interior of the inverter (such as entering through the tailwind outlet).
3、 Inverter shutdown protection
1. Carefully monitor and record the various display parameters on the touch screen of the frequency converter, and promptly report any abnormalities.
2. The temperature of the air outlet of the inverter power unit cabinet cannot exceed 55 ℃.
3. The filter screen on the door of the inverter cabinet should generally be cleaned once a week; If there is a lot of dust in the work environment, the cleaning distance should be shortened according to the actual situation.
4. The ventilation and lighting of the frequency conversion room need to be outstanding, and the ventilation equipment can work normally.
5. It is necessary to keep the frequency conversion room clean and clean it at any time according to the actual situation on site.
6. Carefully monitor and record the ambient temperature of the frequency conversion room, which should be between -5 ℃ and 40 ℃.
7. During normal operation of the frequency converter, a standard thickness A4 paper should be able to adhere to the filter screen at the cabinet door inlet.
4、 Precautions for the use of frequency converter shutdown
1. Tighten the connecting nuts of the internal cables of the frequency converter every six months after six months.
2. After the trial work of the frequency converter is completed, the connection nuts of the internal cables of the frequency converter should be rechecked and tightened.
3. Check that all grounding inside the frequency converter cabinet is secure and the grounding point is free of rust.
4. Use a vacuum cleaner with a plastic nozzle to thoroughly clean the inside and outside of the inverter cabinet, ensuring that there is no excessive dust around the equipment.
5. The operation of the high-voltage switch in the inverter bypass cabinet should be normal, and it should be able to accurately close and disconnect.
6. The connection between the cables inside the frequency converter should be accurate and secure.
7. After long-term shutdown of the frequency converter, the insulation of the frequency converter (including phase-shifting transformer and bypass cabinet main circuit) should be measured, and a 1500V megohmmeter should be used for rehabilitation work. Only after passing the insulation test can the frequency converter be started.
8. Check the ventilation and lighting of the frequency conversion room, and ensure that the ventilation equipment is working properly.
9. Within six months, tighten the connecting nuts of the internal cables of the frequency converter again.
5、 Daily maintenance of frequency converter
1. Strengthen inspections and organize dedicated personnel to be responsible for the regular protection of frequency converters;
2. Record of work data. Record and monitor the operating frequency, current, and temperature of the phase-shifting transformer of the frequency converter at any time. The temperature rise of the phase-shifting transformer cannot exceed 130 ℃.
Napišite tabelo zapisov o delu frekvenčnega pretvornika, da pravočasno zabeležite delovne podatke frekvenčnega pretvornika in motorja, vključno z izhodno frekvenco, izhodnim tokom, izhodno napetostjo, notranjo enosmerno napetostjo frekvenčnega pretvornika, temperaturo radiatorja in drugimi parametri, ter jih primerjajte z razumnimi podatki, da olajšate zgodnje odkrivanje napak in nevarnosti.
3. Prepričajte se, da je temperatura okolice v prostoru s frekvenčnim pretvornikom med -5 in 40 ℃. Določite osebo, ki bo preverila, ali hladilni ventilator na vrhu omarice pretvornika deluje pravilno in ali je filtrirno sito na vratih omarice zamašeno. Prepričajte se, da je kanal za hladilni zrak gladek. Poseben postopek je, da na filtrirno sito na vratih omarice položite papir za tiskanje standardne debeline A4, papir pa pritrdite na okno za dovod zraka.
Da bi zagotovili nemoten pretok hladilnega zraka, je treba filter čistiti enkrat tedensko. Če je na lokaciji veliko prahu, je treba razdaljo čiščenja skrajšati.
4. Spremljanje okolja
(1) Pri visokih temperaturah poleti je treba okrepiti prezračevanje mesta, kjer se nahaja naprava s spremenljivo frekvenco. Zagotovite, da v okoliškem zraku ni prekomernega prahu, kislin, soli, korozivnih ali eksplozivnih plinov;
(2) Poletje je deževno obdobje, zato se izogibajte okolici razsmernika in preprečite vdor dežnih kapljic v notranjost razsmernika. 6. Preverite tesnost vseh električnih povezav in se prepričajte, da v nobenem tokokrogu ni neobičajnih sledi praznjenja, čudnih vonjav, razbarvanja, razpok, poškodb ali drugih pojavov.
5. Po vsaki zaščiti frekvenčnega pretvornika skrbno preverite, ali manjkajo morebitni vijaki, žice itd., da preprečite, da bi majhni kovinski predmeti povzročili kratke stike v frekvenčnem pretvorniku. Še posebej po večjih spremembah električnega tokokroga zagotovite natančno in zanesljivo priključitev električne napeljave, da preprečite pojav "povratnega toka".