What is an electric arc?
An electric arc is a physical phenomenon that occurs during the operation of electrical equipment, characterized by intense brightness and extremely high temperatures.
What are the classifications of power loads?
First-Level Load: Interruption of power supply could result in personal injury or death, or significant political or economic losses.
Second-Level Load: Interruption of power supply could lead to considerable political or economic losses.
Third-Level Load: General power load with minimal impact in case of power interruption.
What is a substation?
A substation is a power supply hub responsible for receiving electrical energy from the power system, transforming its voltage (either stepping it up or down), and then distributing it.
What is the primary role of transformers in a power system?
The main role of a transformer is to change voltage levels, facilitating power transmission. On the same power line, stepping up the voltage through a transformer reduces the transmission current, minimizes line losses, improves transmission efficiency, and enables long-distance power transmission. Conversely, stepping down the voltage meets the varying voltage requirements of different users.
What is the thermal effect of short-circuit current?
When a short circuit occurs, the extremely high short-circuit current causes the conductor's temperature to rise rapidly. This phenomenon is referred to as the thermal effect of short-circuit current.
What are the definition and classifications of secondary circuits?
Secondary circuits are all low-voltage circuits used for monitoring instruments, control operations, signals, relays, and automatic devices. These circuits are categorized by their power sources and purposes into:
Current circuits
Voltage circuits
Control circuits
Signal circuits
What are the conditions for parallel operation of transformers?
Transformers must meet the following conditions for parallel operation:
Equal turns ratio (voltage ratio)
Same connection group
Equal short-circuit impedance
What is switchgear?
Switchgear is a general term for electrical apparatus used in power generation, transmission, distribution, and energy conversion, including associated control, monitoring, protection, and regulation devices.
What is overcurrent?
Overcurrent refers to any current that exceeds the rated current.
What are the indices of power quality?
The key indices of power quality include:
Voltage deviation
Voltage fluctuation and flicker
Total harmonic distortion (THD) of voltage
Frequency deviation
What are the functions of an isolating switch?
Isolate electrical equipment from live networks.
Change operating configurations.
Connect and disconnect small current circuits.
What is a protective relay system?
A protective relay system is a device designed to detect faults or abnormal conditions in the power system and respond by triggering circuit breaker trips or issuing alerts.
What are the main products of low-voltage distribution equipment?
Main products include low-voltage distribution panels, switchgear cabinets, switchboards, lighting panels, power distribution boxes, and motor control centers (MCC).
What is the role of the DC system in substations?
The DC system in substations provides reliable DC power for control signals, protective relays, automation devices, emergency lighting, and operational needs. Its reliability is crucial for the safe operation of the substation, ensuring its continuous and stable performance.