Voorzorgsmaatregelen voor installatie van stroomtransformator met nulsequentie

1. Problemen bij de installatie
(1) Zero-sequence current transformer'>The current transformer should be installed on the bottom plate of the switch cabinet, and should be fixed by a reliable bracket. However, some manufacturers or construction units install the zero-sequence current transformer'>current transformer on the bracket under the bottom plate of the switch cabinet, and even bind the zero-sequence current transformer'>stroomtransformator op de kabel, wat in strijd is met de Het principe van volledig gesloten schakelapparatuur is niet veilig of stofdicht, laat staan ​​kleine dieren, waardoor veel verborgen gevaren ontstaan.

(2) After the cable terminal passes through the external zero-sequence current transformer'>current transformer, the relative position of the cable's metal shielded grounding wire and the external zero-sequence current transformer'>current transformer is incorrect. According to the "Beijing Electrical Engineering Installation Regulations", the metal sheath at the terminal of the three-core power cable must be well grounded; the copper shield of each phase of the plastic cable and the steel armor should be tin-welded with the ground wire (oil-impregnated paper insulated cable lead-clad and armored) The ground wire should be welded), when the cable passes through the zero-sequence current transformer'>stroomtransformator, de metalen kabelmantel en de aardingsdraad moeten van de grond worden geïsoleerd en het kabelaardingspunt (het laspunt tussen de kabelaardingsdraad en de metalen kabelafscherming) bevindt zich onder de transformator, de aardingsdraad moet direct worden geaard ;

When the grounding point is above the transformer, the grounding wire should pass through the transformer for grounding. The grounding wire must be connected to the special grounding copper bar in the switch cabinet. The grounding wire must be copper stranded wire or tinned copper braided wire. The cross section of the grounding wire must be Meet the requirements of the regulations. During the inspection, it was found that some cable grounding wires should pass through the zero-sequence current transformer'>current transformer, and some cable grounding wires should not pass through the zero-sequence current transformer'>huidige transformator. Handel goed.

(3) Due to the relatively large cable terminal, the magnetic circuit of the current transformer'>current transformer is not closed. At present, the commonly used 10kV power cables are three-core XLPE cables. >The current transformer cannot be put on, and the zero-sequence current transformer is disassembled during the construction'>The current transformer interface, the cable is put on, but the interface is forgotten to be restored; some are restored, but the interface is not restored strictly; some terminals The separation of the first three cores is thicker than the zero-sequence current transformer'>current transformer's inner diameter and just stuck in the middle of the zero-sequence current transformer'>current transformer so that the zero-sequence current transformer'>current transformer interface cannot be restored to close, resulting in Zero-sequence current transformer'>Het magnetische circuit van de stroomtransformator is niet gesloten en kan niet normaal werken.

(4) The zero-sequence current transformer'>current transformer's secondary connection was opened during the cable construction, and it was not restored in time after the work was completed, causing the current transformer'>secundaire spoel van de huidige transformator om te openen.

(5) Het aardingsuiteinde van de aardingsdraad van de metalen mantel van de kabel is niet aan de klem gelast, noch verbonden met de aardingskoperstaaf in de schakelkast, maar is terloops om de bouten van het schakelkastlichaam geslagen.

2. Correcte installatiemethode
(1) Er moet voor worden gezorgd dat de stroomtransformator met nulvolgorde is geselecteerd> de binnendiameter van de stroomtransformator is groter dan de buitendiameter van de kabelaansluitkop;

(2) Try not to dismantle the zero-sequence current transformer'>stroomtransformator tijdens de bouw. Als het moet worden afgebroken, moet het na voltooiing van de werkzaamheden in de oorspronkelijke staat worden hersteld;

(3) The grounding wire must be copper stranded wire or tinned copper braided wire, the cross-section of the grounding wire should not be less than 25mm2, the grounding end should be welded with a terminal, and the grounding wire and the zero-sequence current transformer'>stroomtransformator moet op de juiste manier worden gehanteerd. De relatieve positie van de aardingsdraad moet op de aardingskoperstaaf worden geïnstalleerd;

(4) Het beveiligingssysteem met nulvolgorde moet vóór het inschakelen worden aangepast om ervoor te zorgen dat de beveiliging normaal werkt.