In addition to complying with all regulations mandated by the power authorities regarding installation, acceptance, handover testing, commissioning, operation, and maintenance, the following points must also be observed for box-type substations: Upon receipt, the user must carefully inspect the equipment in accordance with relevant regulations; products not intended for immediate installation should be stored in a suitable location under conditions appropriate for normal use. The unit should be lifted from the bottom using specialized lifting gear. Place the unit horizontally on a pre-prepared foundation and install the four anchor bolts (a secondary grouting method may be used); then, seal the gap between the unit's base and the foundation with cement mortar to prevent rainwater from entering the cable compartment. High- and low-voltage cables should be routed in through the bottom sealing plates of the respective compartments, and the gaps between the cables and the conduits must be sealed to ensure waterproofing. Regardless of whether the high-voltage side utilizes overhead lines or underground cables for the incoming supply, a clearly visible disconnection point (such as a drop-out fuse) must be installed near the substation; this provides maintenance personnel with a clear visual indication of whether the substation is live, thereby ensuring their safety. Reliable grounding must be established after the unit is installed in position: the two main grounding terminals on the base channel steel, the transformer neutral point and enclosure, and the lower terminals of the lightning arresters must each be directly grounded by the installation team. All grounding points should share a common grounding system with a resistance of less than 4 ohms, and at least two grounding leads should be connected from the grounding grid to the unit.
The following inspections and tests must be performed after installation or maintenance, and prior to putting the box-type substation into operation: Check for cleanliness inside the substation. Verify the flexibility of operating mechanisms. Ensure the switching (making and breaking) of major electrical components is flexible and reliable. Confirm the reliable and accurate operation of auxiliary electrical contacts. Verify the accuracy of meter and relay operations. Check for correct transformation ratios and wiring polarity of instruments and instrument transformers. Ensure all mounting nuts are tightened and that the installation is secure and stable. Ensure that busbar connections are sound and that supporting insulators and clamping components are securely installed. Verify that the settings of electrical devices meet requirements and that fuse links are of the correct specifications. Confirm that connections in the main and auxiliary circuits comply with the electrical schematic diagram. The resistance of the internal protective grounding system must be less than 0.01 ohms. Dielectric strength tests must be performed on each component in accordance with the applicable voltage ratings.
All components within the box-type substation must be maintained according to their respective technical specifications. If an oil-immersed transformer is used, an oil sample analysis must be conducted at least once a year as required. For high-voltage switchgear in operation, the condition of the contacts and the wear on arc-extinguishing devices must be inspected after 20 load-switching operations or 2,000 no-load switching operations; any abnormalities found must be promptly repaired or the components replaced. Following an automatic trip of low-voltage switchgear, the cause of the trip must be investigated and analyzed; the equipment may only be returned to service after the fault has been rectified. Lightning arresters must undergo preventive testing annually prior to the onset of the thunderstorm season. Before performing maintenance or overhauls on high-voltage switchgear, the incoming power supply to the substation must be disconnected.