Inspections for Wiring and Busbar Installation Processes of High-Voltage Ring Main Units (HV RMUs)
I. Inspections for the Wiring Process of HV RMUs
1、Reliability of Wire Connections — Only one wire is allowed to be connected to each terminal (two wires are permitted if necessary);
2、Protection of Insulated Wires — Insulated wires passing through metal components shall be equipped with protective measures to prevent wire damage;
3、Harness Wiring Requirements — Wiring shall be arranged in harnesses, which must be neat and orderly (horizontal and vertical). The horizontal span of a harness shall not exceed 30 mm, and the vertical span shall not exceed 400 mm. Each harness shall be fixed at least one point;
4、Wires Crossing Metal Partitions in AC Circuits — All phase wires and neutral wires of the circuit shall pass through the same hole when crossing metal partitions.
II. Inspections for the Busbar Installation Process of HV RMUs
1、Quality of Busbar Processing — The surface coating of the busbar (e.g., nickel plating, painting) shall be uniform without flow marks. The bent part of the busbar shall have no cracks or wrinkles exceeding 1 mm in depth. The surface shall be free of peeling, hammer marks, pits, burrs, etc.;
2、Quality of Busbar Installation — The overlapping area of busbars, as well as the specification, quantity, and position distribution of overlapping bolts, shall comply with the provisions of relevant standards. Overlapping bolts must be tightened (tightening torques are specified for bolts and nuts of different specifications). The distance between exposed live conductors of different polarities in the main circuit and between live conductors and the shell shall not be less than 20 mm (related to the rated working voltage and the pollution level of the working environment); the distance between busbars connected to the incoming and outgoing terminals of main circuit electrical components shall not be less than the distance between the terminals of the component.
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