Glossary Of Terms For Power Distribution Equipment

Basic Definitions and Classifications of Power Distribution Equipment
Power distribution equipment is a key device in a power system used for distributing, controlling, and protecting electrical energy. Its core task is to convert high-voltage electrical energy into low-voltage electrical energy suitable for end users and to ensure a safe and stable power supply. It is mainly divided into the following categories:

1. Transformers: These change voltage levels through the principle of electromagnetic induction. Common capacities are 10kV/0.4kV oil-immersed or dry-type transformers. No-load loss must comply with GB/T 6451-2015 standard (e.g., a 100kVA transformer with no-load loss ≤170W).

2. Switchgear: Used for power distribution and line protection. Based on structure, it is divided into fixed type (e.g., GGD) and drawer type (e.g., GCS). Rated current is typically 630A~4000A, and short-circuit withstand capability reaches 25kA/1s.

3. Circuit Breakers: Equipped with overload and short-circuit protection, frame circuit breakers (such as the DW series) have a breaking capacity of up to 65kA, while miniature circuit breakers (MCBs) are used for end-point protection, with a breaking capacity typically ranging from 6kA to 15kA.

Key Equipment Technical Parameters and Selection Logic

1. Voltage and Current Parameters:

- Low-voltage distribution equipment has a rated voltage of 400V (three-phase) or 230V (single-phase), while high-voltage equipment is mostly 10kV or 35kV.

- Current rating needs to be selected based on load calculations. For example, 1600A~2500A circuit breakers are commonly used for main power lines in commercial buildings.

2. Protection Rating:

- Outdoor prefabricated substations must meet an IP54 dust and water resistance rating (according to IEC 60529), while indoor switchgear is generally IP30.

3. Intelligentization Trend:

Modern power distribution equipment integrates sensors and communication modules (such as LoRa and NB-IoT), supporting remote monitoring of data such as current and temperature, reducing fault response time to milliseconds.

Application Scenarios and Maintenance Points:

1. Industrial Scenarios: Equipment resistant to high harmonic pollution (such as K-factor transformers) should be selected, and infrared temperature measurement should be performed regularly (recommended once per quarter, with a temperature difference alarm threshold of 15℃).

2. Residential Scenarios: Residual current circuit breakers (operating current ≤30mA, response time <0.1s) conforming to GB/T 16916.1 standard should be prioritized.

3. Maintenance Specifications:

- Transformer oil breakdown voltage (≥35kV/2.5mm gap) should be tested every 3 years;

- Circuit breaker mechanical life should reach over 10,000 cycles (according to GB/T 14048.2).