High and low voltage switchgear, as a key component of the power system, undertakes the important functions of power distribution, control, and protection. In power distribution projects, high and low voltage switchgear acts as the "transportation hub" of electricity, rationally distributing power to various electrical devices and circuits. It can effectively control the on/off state of circuits, and can promptly cut off the power supply in case of overload, short circuit, or other faults, protecting the safety of equipment and personnel.
For example, in the power distribution project of a large commercial center, high- and low-voltage distribution cabinets need to provide power to various equipment such as lighting systems, air conditioning systems, and elevators. If the distribution cabinets malfunction, some or all of the equipment may fail to operate normally, affecting the normal operation of the mall. Therefore, the installation and construction quality of high- and low-voltage distribution cabinets is directly related to the safe and stable operation of the entire power distribution project.
Prioritize well-ventilated indoor spaces that are sufficiently far from sources of moisture and corrosive gases as installation sites. Good ventilation ensures that the heat generated by the distribution cabinet during operation can be dissipated in a timely manner, preventing excessive temperature from affecting the equipment's performance and lifespan. Being away from sources of moisture and corrosive gases prevents the distribution cabinet from being corroded and damaged.
Ensure sufficient space is left around the distribution cabinet to allow for smooth operation and maintenance. Generally, at least 0.8 to 1 meter of space should be reserved around the distribution cabinet for personnel to perform switching operations, inspections, and other tasks.
Carefully inspect the exterior of the distribution cabinet to ensure it is undamaged; meticulously check the integrity of the internal components to ensure no parts are missing or damaged. For example, check if the cabinet door can be opened and closed normally, and whether there are scratches or deformations on the cabinet surface. For internal switches, meters, and other components, check whether they are securely installed and whether there are any signs of damage.
Strictly compare the model and specifications of the distribution cabinet to ensure they precisely match the design requirements. Different power distribution projects have different requirements for the model and specifications of the distribution cabinet. If the model and specifications of the distribution cabinet do not meet the design requirements, it may cause it to malfunction or even lead to safety accidents.
Prepare all necessary installation tools, such as screwdrivers, electric drills, and wrenches. These tools are essential for installing the distribution cabinet and must be complete and in good condition.
Carefully inspect the tools to ensure they are in good working order and meet all safety standards. For example, check the insulation of the drill and the opening of the wrench.
Prefabricate the basic steel frame according to the drawings and perform anti-corrosion treatment. The size and shape of the basic steel frame should be made according to the specifications and design requirements of the distribution cabinet. Anti-corrosion treatment can be carried out by galvanizing, painting, etc., to extend the service life of the basic steel frame.
Place the prefabricated foundation steel frame on the reserved iron parts according to the location marked on the construction drawings. After leveling and aligning, weld the foundation steel frame, embedded iron parts, and shims firmly with electric welding. Finally, the top of the foundation steel frame should be 10mm higher than the leveled ground to prevent water from the ground from entering the distribution cabinet.
If a concrete foundation is used, it should be poured according to the specifications of the distribution cabinet. For example, the foundation dimensions for a non-standard distribution cabinet may be 1200mm × 600mm × 300mm, and C25 concrete should be used. During the pouring process, care should be taken to ensure compaction and avoid defects such as honeycomb or pitted surfaces.
The basic curing time should be no less than 7 days. Subsequent installation work can only proceed after the compressive strength reaches 70% of the design value. During the curing period, the foundation surface should be kept moist, which can be achieved by covering it with plastic film or watering.
Install the distribution cabinet according to the design drawings, using a combination of forklifts and manual labor for placement. Use soft slings during hoisting to prevent scratching the paint. After placement, adjust the horizontal and vertical alignment of the distribution cabinet to meet requirements. Generally, the vertical deviation of the distribution cabinet should not exceed 1.5‰ of the cabinet height.
Secure the distribution cabinet to the ground firmly using screws or other standard fasteners to ensure sufficient stability. The specifications and quantity of the fasteners should be selected based on the size and weight of the distribution cabinet.
Cable connections should be made in accordance with electrical specifications to ensure secure connections and prevent leakage and short circuits. When connecting cables, pay attention to the cable type, specifications, and phase sequence to ensure they match the requirements of the distribution cabinet. Cable connections should be made using methods such as crimping or welding, and the connection points should be insulated to prevent leakage.
For example, when connecting high-voltage cables, the operating procedures must be strictly followed to ensure connection quality. At the same time, the cables must be secured to prevent loosening due to cable movement.
Grounding must be implemented to ensure the safety of the distribution cabinet and prevent leakage accidents. The connections between the distribution cabinet body, internal equipment, and all components should be secure, and the cabinet body should have a visible and reliable grounding device. Openable cabinet doors containing electrical appliances should be reliably connected to the grounded metal frame using flexible wires.
The grounding resistance should meet the design requirements. Generally speaking, the grounding resistance of low-voltage distribution cabinets should not exceed 4Ω, and the grounding resistance of high-voltage distribution cabinets should not exceed 10Ω.
Perform functional tests on the distribution cabinet to ensure that all indicators meet the design requirements. Functional tests include switch opening and closing tests, protection device operation tests, and instrument accuracy tests. For example, test whether the switch opening and closing time meets the requirements, and whether the protection device can operate in a timely manner under overload, short circuit, and other conditions.
Check that the safety protection measures of the distribution cabinet are in place to ensure there are no safety hazards. Safety checks include verifying that the cabinet door interlocking devices are functioning properly, that the protection level meets requirements, and that electrical clearances and creepage distances meet standards.
Record the commissioning results and acceptance status in a document for future reference. The acceptance record should include the distribution cabinet's model, specifications, installation location, commissioning data, and acceptance conclusions for future retrieval and maintenance.
In power distribution projects, project management for the installation of high and low voltage switchgear is crucial. The project manager should organize relevant personnel to conduct on-site surveys, understand the installation environment and conditions, assess the site's power load, spatial layout, and ventilation conditions, and ensure that the switchgear installation location is appropriate.
Each stage should have designated personnel responsible for ensuring smooth information flow and avoiding errors caused by poor communication. For example, in the equipment procurement stage, it is essential to ensure that the purchased distribution cabinets and related accessories meet standards and are environmentally friendly; in the installation stage, construction must be carried out strictly in accordance with operating procedures to ensure installation quality.
Construction must be carried out strictly in accordance with relevant standards and specifications to ensure the installation quality of high and low voltage distribution cabinets. During construction, quality inspections must be strengthened, with strict control over every step. For example, in the foundation construction stage, the dimensions and strength of the foundation must be checked to ensure they meet requirements; in the distribution cabinet installation stage, the levelness, verticality, and cable connections of the distribution cabinet must be checked to ensure they meet standards.
At the same time, a quality traceability system should be established to record every step of the construction process so that quality problems can be traced and dealt with in a timely manner.
In conclusion, the installation and construction of high and low voltage distribution cabinets is a crucial part of power distribution engineering projects. It is necessary to strictly follow relevant standards and specifications, strengthen project management and quality control, and ensure the safe and stable operation of the distribution cabinets to guarantee the smooth implementation of the entire power distribution project.