In the realm of crane operations, safety is of paramount importance. The safe operation procedures for cranes typically emphasize maintaining a sufficient distance from power lines. Vendar, in the real world of practical operation, especially in confined and narrow spaces, it can be an extremely challenging task to maintain an adequate safe distance. A review of numerous hoisting accident cases reveals that there are a significant number of instances where the crane boom comes into contact withhigh-voltage lines.
On June 20, a tragic incident occurred in Yuncheng when a crane accidentally touched ahigh-voltage line, resulting in a fatal outcome. When the crane boom makes contact with ahigh-voltage line, electricity is conducted through the metal crane boom, electrifying the entire vehicle body. Ustrezno osebje v vozilu in v bližini bo v nevarnosti, da jih bo stresla napetost dotika oziroma napetost koraka. Zaradi izjemne moči high-voltage lines in vključene visoke napetostne ravni, tisti, ki so šokirani, se zlahka hudo poškodujejo ali celo izgubijo življenje.
torej, ali obstaja bolj znanstveni pristop, ki lahko prepreči šok ljudi, tudi če se žice po nesreči dotaknejo? Odgovor je pritrdilen. Poseben tehnični ukrep je dodajanje začasne ozemljitvene zaščite na žerjavu.
Naprava za začasno ozemljitev je sestavljena iz več ključnih komponent. Prvič, tam je ozemljitvena bakrena žica. Ta je sestavljen iz več pramenov, visokokakovostna posebna mehka bakrena žica dolga več metrov in s premerom najmanj 25 mm. It is also covered with an outer transparent plastic sheath layer. This copper wire is designed to conduct electricity safely to the ground. The multi-strand construction ensures flexibility and durability, while the large diameter allows for a high current-carrying capacity. The transparent plastic sheath provides insulation and protection, preventing accidental contact with the wire and reducing the risk of electrical hazards.
Drugič, there are the connecting wire clips. These are fixed at both ends of the grounding wire and are used to connect the vehicle body and the grounding pile. The wire clips must be of high quality and firmly attach to the respective surfaces to ensure a reliable electrical connection. Zasnovani so tako, da prenesejo sile in tresljaje, ki nastanejo med delovanjem žerjava, in preprečijo nenamerno odklop.
Končno, tam je začasna ozemljitvena elektroda, znan tudi kot ozemljitveni kup ali palica. To mora biti kovinski stožec z dolžino večjo od 120 cm in površino prečnega prereza večjo od 190 mm².. Velika velikost in kovinska konstrukcija ozemljitvenega pilota zagotavljata dober stik s tlemi in pot nizkega upora za električni tok. Stožčasta oblika omogoča enostavno zabijanje kupa v tla in zagotavlja stabilnost.
Poseben postopek delovanja naprave za začasno ozemljitev je naslednji. Ko žerjav izbere položaj in spusti opornike, vendar pred dvigom, upravljavec mora upoštevati določene varnostne ukrepe. Around the crane site, first, a high-quality and solid soil surface should be selected. This is crucial as the quality of the soil affects the effectiveness of the grounding. A sledgehammer is then used to drive the grounding pile into the ground more than 80 centimeters deep. This depth ensures a good connection with the earth and a low resistance path for the electrical current. After the grounding pile is in place, the wire clips at both ends of the grounding wire are fixed to the grounding pile and the vehicle body respectively. The contact part of the vehicle body must be a metal surface without paint. Paint can act as an insulator and block the flow of electrical current. Zato, it is essential to ensure a clean metal-to-metal contact for effective grounding. After taking these measures, voznik lahko vstopi v vozilo in deluje z večjo stopnjo varnosti. Ko je operacija žerjava končana in je roka žerjava nameščena in pospravljena, ozemljitveno žico je mogoče odstraniti.
Po ozemljitvi, tudi če se roka žerjava po nesreči dotakne črte in prevaja elektriko, tok kratkega stika zaradi napake bo tekel v zemljo skozi karoserijo vozila preko ozemljitvene žice. To ohranja celotno karoserijo vozila pri enakem potencialu kot zemlja, močno oslabi vpliv električne energije na človeško telo. Voznik vstopa in izstopa iz vozila, zemeljsko osebje, ki podpira dvignjeni tovor, in drugo osebje v bližini karoserije vozila ne bo v nevarnosti, da bi jih močna napetost dotika pretresla. To lahko znatno zmanjša smrtno nevarnost in s tem zmanjša število žrtev. Ob istem času, ozemljitvena žica razprši napako velik tok, ki poteka skozi kolesa, ki se lahko izogne nevarnosti požara zaradi eksplozije pnevmatik in požara ter zmanjša materialne izgube.
Vendar, poudariti je treba, da ozemljitev ne pomeni, da je med delovanjem lahko nepreviden ali nepremišljen. Dotikanje električnih vodov mora biti vedno strogo prepovedano. Tudi z ozemljitveno zaščito, eksplozija potencialne razlike nadzemnih daljnovodov je enako grozljiva. Izjemno nevarne so tudi nesreče v električnem omrežju in izpadi električne energije, in še vedno obstaja nevarnost stopenjske napetosti. Poleg tega, če se ukrepi ozemljitvene žice ne izvajajo dosledno, še vedno obstaja nevarnost električnega udara. Implementing grounding protection measures is the last protective barrier and should only be considered as a last resort.
When grounding, the following four points should also be carefully observed. Prvič, do not use other metal wires instead of grounding wires. Na splošno, metal wires other than the specified grounding wire have a low current-carrying capacity. When a short-circuit large current occurs, these wires will be instantly burned off, making the vehicle body return to a high voltage state once again. This can pose a serious threat to the safety of personnel. Drugič, the connection surface of the wire clip should be clean and free of debris. It cannot be fixed on a painted surface as that will block the path of the fault current. The connection point should be compact and firm to ensure a reliable electrical connection. The vehicle body is preferably equipped with a specially set galvanized hanging connection point to avoid unfavorable contact surfaces such as paint. Thirdly, the grounding pile should be selected on a damp and good soil original ground. It must not be placed in a scene of piled loose soil, cement, or stones. Loose soil, cement, and stones can have a higher resistance and may not provide a good grounding connection. Damp soil with good conductivity is ideal for effective grounding. Končno, to avoid possible step voltage, people must stay more than 3 meters away from the temporary grounding electrode, vehicle body, and support. Stopenjska napetost je napetostna razlika med dvema točkama na tleh zaradi pretoka električnega toka skozi zemljo. Zadrževanje na varni razdalji pomaga zmanjšati tveganje šoka zaradi napetosti koraka.
Na primer, predstavljajte si gradbišče, kjer deluje žerjav. V zaprtem prostoru, nevarnost, da bo roka žerjava prišla v stik z high-voltage lines se poveča. Brez ustrezne ozemljitvene zaščite, če pride do takšne nesreče, posledice so lahko katastrofalne. Ljudje na žerjavu in v bližini se lahko hudo poškodujejo ali celo izgubijo življenje. Vendar, z uporabo začasne ozemljitvene zaščitne naprave ter upoštevanjem pravilnih postopkov in previdnostnih ukrepov, tveganje električnega udara se lahko znatno zmanjša. Voznik in zemeljsko osebje lahko delata bolj samozavestno in varno, knowing that there is an added layer of protection in place.
Za zaključek, reducing casualties caused by cranes touchinghigh-voltage lines requires a combination of careful operation, proper safety procedures, and the implementation of effective grounding protection measures. By being aware of the risks and taking the necessary precautions, crane operators and those working around cranes can minimize the potential for accidents and protect lives and property.
