The 40.5 kV VD4 vacuum circuit breaker is suitable for indoor switchgear systems with air insulation. Under normal operating conditions and within the circuit breaker's technical parameters, the VD4 vacuum circuit breaker can meet various operational requirements of the power grid under normal or fault conditions, including closing and interrupting short-circuit currents. The vacuum circuit breaker exhibits excellent performance in applications requiring frequent operation and/or short-circuit current interruption. The VD4 vacuum circuit breaker meets the requirements for automatic reclosing and possesses extremely high operational reliability and service life. The VD4 vacuum circuit breaker is available in both withdrawable and fixed installation types. Its basic structure is shown in Figures 3/1 and 3/2, and Figures 3/7 and 3/8. 1.2 Standards and Specifications The manufacture of VD4 vacuum circuit breakers conforms to standards and specifications consistent with relevant publications of GB, IEC, and DIN VDE: • GB/T 11022, IEC 62271-1, and DIN VDE 0670 part 1000, "Common Technical Conditions for Standards of High Voltage Switchgear and Controlgear" • GB/T 1984 and IEC 62271-100 "High Voltage AC Circuit Breakers" Meets E2, C2, M2 (10000 cycles) ratings

Normal Operating Conditions Ambient Air Temperature • Maximum +40℃ • Average over 24 hours not exceeding +35℃ • Minimum (Indoor) -5℃ Note: -25℃ operating temperature option available. Humidity • Average relative humidity over 24 hours not exceeding 95% • Average water vapor pressure over 24 hours not exceeding 2.2 kPa • Average relative humidity over 1 month not exceeding 90% • Average water vapor pressure over 1 month not exceeding 1.8 kPa Altitude ≤1000 m. Seismic Performance Seismic intensity not exceeding magnitude 8. Adaptability to Humid Tropical Climates VD4 circuit breakers are designed/manufactured in strict accordance with standards and can be used in humid, hot, and high-salinity climates. All critical components are specially treated to withstand the corrosion of Class C ambient environments specified in EN 12500 class 5. The galvanizing process is carried out according to UNI ISO 2081 standard, classification number Fe/Zn 12, with a thickness of 12 μm, and color chromate passivation is performed according to UNI ISO 4520 standard. Altitude: The insulating properties of air decrease with increasing altitude; therefore, the impact of this phenomenon on the external insulation of the switch must be considered when using it at high altitudes. The insulation inside the arc-extinguishing chamber is not affected, as its insulation capacity is guaranteed by vacuum. If the switch is installed in an area above 1000 m altitude, the effect of altitude should be considered during the design phase of the insulation components. In this case, a correction factor must be considered, which can be found in the chart on the right, based on the IEC 62271-1 standard. An example calculation based on the above correction principle is given below. Example: • Installation Altitude: • Rated Voltage: • Power Frequency Withstand Voltage: • Lightning Impulse Withstand Voltage: 2000 m 1 2 kV 4 2 kVrms 75 kVp • Ka coefficient, found from the chart: Ka=1.13 From the above parameters, the components must be able to withstand (test conditions at zero altitude): • Power Frequency Withstand Voltage: 42 x 1.13 = 47.5 kVrms • Lightning Impulse Withstand Voltage: 75 x 1.13 = 84.7 kVp The above calculations show that circuit breakers used in high-altitude areas must be able to withstand higher insulation level tests at zero altitude. For specific circuit breaker selection, please contact the manufacturer.

The 40.5 kV VD4 vacuum circuit breaker is suitable for indoor switchgear systems with air insulation. Under normal operating conditions and within the circuit breaker's technical parameters, the VD4 vacuum circuit breaker can meet various operational requirements of the power grid under normal or fault conditions, including closing and interrupting short-circuit currents. The vacuum circuit breaker exhibits excellent performance in applications requiring frequent operation and/or short-circuit current interruption. The VD4 vacuum circuit breaker meets the requirements for automatic reclosing and possesses extremely high operational reliability and service life. The VD4 vacuum circuit breaker is available in both withdrawable and fixed installation types. Its basic structure is shown in Figures 3/1 and 3/2, and Figures 3/7 and 3/8. 1.2 Standards and Specifications The manufacture of VD4 vacuum circuit breakers conforms to standards and specifications consistent with relevant publications of GB, IEC, and DIN VDE: • GB/T 11022, IEC 62271-1, and DIN VDE 0670 part 1000, "Common Technical Conditions for Standards of High Voltage Switchgear and Controlgear" • GB/T 1984 and IEC 62271-100 "High Voltage AC Circuit Breakers" Meeting E2, C2, M2 (10000 cycles) ratings

ABB VD4/AF Product Performance 1. High-Performance Vacuum Breaking Technology Utilizing the vacuum arc-extinguishing principle, it can quickly extinguish the arc, providing excellent insulation recovery and breaking performance while reducing contact burn-off. 2. Reliable Short-Circuit Current Breaking Capacity VD4/AF can be used for switching normal load currents in medium-voltage power distribution systems and can break fault currents according to the rated parameters of specific models, providing protection for lines, transformers, and other medium-voltage equipment. 3. High Mechanical Durability The operating mechanism is designed for the long-term operation requirements of medium-voltage switchgear, meeting the requirements of frequent operation and long-term use. Specific mechanical life ratings and number of operations should refer to the technical datasheet for the corresponding VD4/AF model. 4. Stable Electrical Life The contacts inside the vacuum interrupter operate in a vacuum environment, resulting in relatively less arc erosion of the contacts, which helps maintain stable breaking performance over a long period. 5. Fast and Stable Closing and Opening Performance: The circuit breaker operating mechanism can quickly complete closing and opening actions, and cooperates with the relay protection system to promptly disconnect faulty circuits after detecting short circuits or other faults. 6. Reliable Operating Mechanism: Utilizing an energy storage mechanical operating mechanism, it can be equipped with energy storage motors, closing coils, opening coils, auxiliary contacts, and other accessories, supporting both on-site and remote electrical operation. 7. Comprehensive Control and Protection Coordination Capabilities: It can cooperate with relay protection, measurement, and automation control systems to achieve functions such as fault protection, remote closing and opening, status feedback, and electrical interlocking. 8. Low Maintenance Workload: The vacuum interrupter uses a sealed design, eliminating the need for replenishing the arc-extinguishing medium. Under normal operating conditions, maintenance is mainly concentrated on the operating mechanism, transmission system, and auxiliary control circuits. 9. Applicable to Medium-Voltage Switchgear: The VD4/AF can be used in medium-voltage switchgear of corresponding designs, suitable for various circuits such as incoming lines, feeders, transformers, and industrial power distribution. 10. Wide Range of Typical Applications: Commonly used in medium-voltage power distribution systems in power distribution, substations, industrial production lines, steel, cement, mining, petrochemical, and infrastructure industries. VD4/AF Core Performance Summary: Vacuum arc extinguishing + Reliable short-circuit breaking + Long mechanical life + Stable operating mechanism + Low maintenance requirements + Compatibility with automated control