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Function: Transformers change voltage levels for efficient power transmission. Step-up transformers increase voltage to reduce line losses, while step-down transformers convert high voltage to required user levels.
Types:
Dry-type
Oil-immersed: Includes self-cooling, air-cooled, forced oil-air, and forced oil-water types.
Modeling:
Example: SZ-50000/110 indicates a three-phase on-load tap changing transformer with a capacity of 50,000 VA and a high voltage winding of 110 kV.
Function: High-voltage circuit breakers connect and disconnect load and no-load currents, protecting the system from faults by quickly cutting off the power.
Types:
Based on installation location: indoor and outdoor.
Based on arc-extinguishing medium: oil, air, vacuum, and SF6 (sulfur hexafluoride).
Example: ZN4-10/600 denotes an indoor vacuum circuit breaker rated at 10 kV and 600 A.
Function: Isolating switches (knife switches) provide safety isolation during maintenance and cannot interrupt load or short-circuit currents. They should be used in conjunction with circuit breakers.
Types:
Based on installation: indoor and outdoor.
Movement types: horizontal, vertical, and inserted.
Insulator configurations: single, double, and triple pillar types.
Operation: Must be operated after opening circuit breakers to ensure safety.
Function: Similar to transformers, they reduce high currents to measurable levels (typically 5A or 1A) for instruments and protective devices. They must not be open-circuited as this can lead to high voltage hazards.
Function: Converts high voltages to lower standards (e.g., 100V) for measurement and protection purposes while isolating high voltage from personnel.
Advantages of Capacitive Voltage Transformers:
Multifunctional (also serves for high-frequency communication).
Higher impulse strength compared to electromagnetic types.
Smaller size and lighter weight.
Disadvantages: Less accurate than electromagnetic types.
Overview: A compact design that uses SF6 gas for insulation, integrating multiple components (circuit breakers, isolators, etc.) into a single unit. It is favored for space-saving and operational safety but comes with high costs.
Function: Power capacitors provide reactive power compensation, reducing energy losses, improving voltage quality, and enhancing system capacity.
Coupling Capacitor: Isolates high voltage from low voltage systems while allowing high-frequency signals to pass.
High-Frequency Blocking Coil: Prevents high-frequency currents from leaking into substations, minimizing energy losses.
Function: Collects and distributes electrical energy in substations, connecting transformers and various electrical devices. Materials include copper, aluminum, and aluminum alloys.
Applications: Used for power lines in plants and substations, especially in challenging terrains.
Advantages: Moisture and corrosion resistance, unobtrusive, and reliable operation.
Disadvantages: High cost, complex installation, and maintenance challenges.
