Forholdsregler for installation af nulsekvensstrømtransformer

1. Problemer med installationen
(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'>strømtransformer på kablet, hvilket overtræder princippet om fuldt lukket koblingsudstyr er hverken sikkert eller støvtæt, endsige smådyr, hvilket efterlader mange skjulte farer.

(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'>strømtransformatoren, kablets metalkappe og jordledningen skal være isoleret fra jorden, og kabeljordingspunktet (svejsepunktet mellem kablets jordledning og kabelmetalskærmen) er under transformeren, jordledningen skal være direkte jordet ;

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'>strømtransformer. Handle rigtigt.

(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'>Strømtransformatorens magnetiske kredsløb er ikke lukket og kan ikke fungere normalt.

(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'>strømtransformatorens sekundære spole for at åbne.

(5) Den jordede ende af kablets metalkappe-jordledning er ikke svejset til terminalen og heller ikke forbundet til jordforbindelsens kobberstang i afbryderskabet, men er tilfældigt overlappet på boltene på afbryderkabinettet.

2. Korrekt installationsmetode
(1) Det skal sikres, at nul-sekvens strømtransformatoren er valgt > strømtransformatorens indre diameter er større end den ydre diameter af kabelterminalhovedet;

(2) Try not to dismantle the zero-sequence current transformer'>strømtransformer under byggeriet. Hvis det skal demonteres, skal det genoprettes til sin oprindelige tilstand, efter at arbejdet er afsluttet;

(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'>strømtransformatoren skal håndteres korrekt. Den relative position af jordledningen skal installeres på den jordede kobberstang;

(4) Nulsekvensbeskyttelsessystemet bør justeres før tænding for at sikre, at beskyttelsen fungerer normalt.