Classification of Electrical Equipment:

Primary Equipment: Directly involved in the production, transmission, and distribution of electrical energy, such as generators, transformers, switchgear, and power cables.

Secondary Equipment: Auxiliary devices that monitor, measure, control, and protect the operation of primary equipment, including instruments, relays, control and signal devices.

Transformer Temperature Monitoring:

The temperature indicated by the transformer's thermometer represents the upper layer oil temperature of the transformer oil tank.

During winter, the temperature rise should not exceed 55°C, and in summer, the maximum temperature should not exceed 85°C.

Load Types:

Peak Load (Maximum Load): The highest load value within one hour of a 24-hour period for the grid or user.

Average Load: Can be classified into daily average load, monthly average load, and annual average load.

First-Class Load: Should be supplied by two power sources. If one source fails, the other should automatically switch on and maintain the main load. Additionally, an emergency power source (independent generator set or a dedicated feeder line independent of the normal power supply, such as a battery bank) must be provided, suitable for applications requiring millisecond-level power interruptions.

Second-Class Load: Supplied by one power source with another as backup. If the main source fails, the backup should manually switch on and maintain the main load.

Substation and Power Distribution:

A substation and power distribution station (referred to collectively as a substation) aim to improve equipment utilization and significantly enhance power quality.

Natural Compensation Power Factor Methods: Avoid no-load or light-load operation of motors and equip welding machines with no-load stop devices.

Artificial Compensation Power Factor Methods: Centralized compensation and individual compensation.

Low-Voltage Capacitor Compensation:

Should have a separate control switch, preferably a low-voltage circuit breaker.

Switches and wires should be calculated at 2A per kVAr.

Capacitors must have short-circuit protection, and if using a fuse, the rated current of the fuse should be calculated at 2.5A per kVAr.

Discharge circuits for capacitor banks must not include manual switches or fuses.

Capacitor racks should not exceed three layers, and there should be no horizontal partitions between layers to ensure proper heat dissipation.

The distance between the live terminal of the capacitor and the bottom of the capacitor case should be at least 100mm.

The operating voltage and current of the capacitors must not exceed 1.1 times the rated voltage and 1.3 times the rated current, respectively.

The ambient temperature of the capacitor room and the temperature rise of capacitors in summer should not exceed 40°C.

After each power outage, capacitors should be discharged for three minutes before re-energizing.

If there are serious overheating issues with capacitor terminals or significant discharges from bushings, power should be immediately cut off to prevent accidents.

Inspection and Maintenance of Low Voltage Distribution Devices:

For manned stations, inspect once per shift; for unmanned stations, inspect weekly. General cleaning and inspection should be conducted at least twice a year.

Special inspections are required during peak load periods, high temperatures, strong winds, heavy rain, thunderstorms, or in case of accidents and overload operation.

If low-voltage circuit breakers or fuses trip repeatedly, the setting values and fuse ratings should be checked and recalibrated if necessary.

If the low-voltage distribution branch trips immediately upon energizing, the switch itself should be inspected for defects.

Low-voltage distribution rooms must ensure "five preventions and three communications": fire prevention, water prevention, leakage prevention, rain and snow prevention, small animal prevention, good ventilation, clear access, and normal communication.

Household Load Connections:

For calculated load currents ≤ 40A (8kW for residential, 10kW for non-residential users), single-phase entry is required.

For load currents > 40A, three-phase entry is required.

The entry point should be ≥2.9m above ground, and the vertical distance between the entry pipe and the connection wire should be<0.5m.

The entry structure should be sturdy, dry, waterproof, easy to maintain, safe for construction, close to the power supply line, and as near to the load center as possible.

For single-phase entry lines, use 40x40x5mm angle iron; for three-phase, use 50x50x6mm angle iron.

10m cement poles should be buried 1.7m deep, and entry wires must use copper core insulated wires of at least 6 square millimeters, without joints.

For wire cross-sections ≥35 square millimeters, to prevent rainwater from seeping indoors, a V-shaped cut should be made at the lowest point of sag for water drainage.

The total cross-sectional area of wires inside the entry pipe should not exceed 40% of the effective cross-sectional area of the pipe hole.

Distribution Room Setup:

Fixed distribution panels in the room should have a minimum operating aisle width of 2m for double rows facing each other.

For aisles longer than 7m, there should be two exits, preferably located at both ends of the distribution room.

A reliable safety lighting system must be installed, with switches located at the entrance.

Instruments, signal indicators, and alarm devices of the distribution setup should be functional and complete.

There must be a clearly defined disconnection point before the main switch, such as a disconnect switch or fuse.

Loads controlled by the distribution device must be managed individually by separate switches.

Insulating mats should be laid in the operation and maintenance paths around the distribution device, and no other items should be stored in these paths.