Pêşkêşkirina Planê ya Transmisyonêya Mekanîkî ya Sêfaseyî ji bo Basklêka Tenzorê 252kV yên Nîşandaran Sûfuri Hexafluoride

Pêşkêşkirina û Pêşkeftina Lînkîyên Mekanîkî ya Sêphasel bi Arberên Tankî SF₆ ya 252kV di Cihanelectrica Berdîna Mezin de

Di cihantransmîsyona berdîn mezinda Çîn de, pêşkêşkirina sêphaselan taybetandî hatî ye, da ku agahetirî elektrîkîya berdîn mezinda van di rêzikî sêphaselan de saz kirin. Pirrûbarî ji wan arberên tankî SF₆ ya 252kV da ku heta ne hatin saz kirin bi rêzikî phase-separated, ku her phase bi mekanîzmeya motor-spring werazî yên nehatîn. Lînkîyên mekanîkî sêphaselan bi lînkîyên elektrîkî hatin qebûl bikin bi bîra boxa control junction. Lekin, lînekîyên elektrîkî yan dest bi nîrvana xarabkirina li ser ast, yekemîn operasyonên nîsankirina full-phase û sîncronizasyonê zêdetir tunebikin. Wan pirsgirêzek ên bi aborî digerînên berdîn mezinda, veqetandinê ya stresên surgeyan li ser transmisyon line. Bi tenê vê çendina çareserkirina û bixweberiya operasyonê, biryarîkî mekanîkî sêphaselan hate çêkirin da ku bixweberiya drive bi mekanîzmeyek ek hatin qebûl bikin, bi eva sîncronizasyonê sêphaselan zêde bike û çewtên fase-loss anîse.

Biryarîkî
Parastîna Lînkîyên Elektrîkî û Mekanîkî

• Lînkîyên Elektrîkî Sêphaselan: Îstibda kirin mekanîzmeyên operasyonê taybetandî (wate, CT20 motor-spring mekanîzmeyên ji bo produktên LW24-252), ku lînkîyên interphase bi lînkîyên elektrîkî di boxa control de hate qebûl bikin. Her phase's drive shaft directly connects to its respective arc-quenching chamber. Protection systems employ three-phase position mismatch relays to trigger tripping.

• Lînkîyên Mekanîkî Sêphaselan: Îstibda kirin mekanîzmeyek hydraulics-spring, ku kameryên arc-quenching sêphaselan bi connecting rods mekanîkî hatin qebûl bikin. Ji bo arberên circuit breaker 252kV tank-type bi layoutan horizontal arc-quenching chamber (common in outdoor substations), the operating mechanism and drive system are positioned in front of the chambers, requiring re-optimized design for mechanism mounting, drive trains, and support structures.

Retrofit of LW24-252 Circuit Breakers

The original LW24-252 features phase-separated operation with three CT20 mechanisms. To achieve mechanical linkage:

• Upgraded Operating Mechanism: Replaced with a high-power hydraulic-spring mechanism (e.g., CYA5-5) to meet the increased operational energy requirements (calculated single-phase switching energy necessitates a robust hydraulic design).

• Seal Structure Improvement: Converted from direct-acting seals (using compressed PTFE V-gaskets with high friction and cost) to rotary lip seals for reduced operating force and improved reliability.

• Rigid Interphase Fixing: Installed connecting plates to maintain interphase spacing and enhance drive rigidity.

• Dual-Tie Rod System: Employed dual tie rods to transmit torque and prevent deformation during switching, ensuring synchronized movement.

• Integrated Mechanism Box: Redesigned to accommodate the single hydraulic mechanism, streamlining control and mechanical interfaces.

Working Principle and Structure

The hydraulic-spring mechanism drives a piston rod in linear motion, which is converted to rotational motion via a drive crank arm. This motion is transmitted through tie rods to synchronize the three phases. A crank arm box then converts rotational motion back to linear motion to actuate the moving contacts within the arc-quenching chambers.

• Closing Process: The piston rod moves rightward, driving the crank arm to rotate the drive shaft counterclockwise. This motion is transferred via tie rods to all three phases, pushing the internal tie rods inward until the contacts close fully.

• Opening Process: Motions are reversed, with the piston rod retracting to pull the contacts apart.

Strength Design of Drive Components

To maintain original mechanical characteristics under three-phase linkage, the hydraulic-spring mechanism's high operational energy (e.g., 10,000J total switching energy) necessitates reinforced crank arms and tie rods. Finite element analysis ensures stress distribution within material limits during high-energy operations.

Mechanism Selection and Debugging
Hydraulic-Spring Mechanism Features

• Advantages: Compact design, high integration, large operating energy (2540J for closing, 10005J for tripping), minimal temperature impact, and high reliability.

• Technical Parameters:

• Rated operation cycle: Open - 0.3s - Close-open - 180s - Close-open

• Rated oil pressure: 48.7MPa ±3MPa

• Energy storage time: ≤60s per cycle

• Mechanical life: 5000 cycles (M2 grade: 10,000 cycles)

Debugging and Performance

• Energy Matching: The CYA5-5 mechanism (10,000J total energy) meets the 252kV circuit breaker's requirements (6500J for tripping, 3500J for closing), with safety margins ensured.

• Synchronization: Three-phase switching synchronization is improved to ≤3ms (vs. conventional LW24-252's 3ms baseline), achieved through hydraulic flow regulation in solenoid valves.

• Cost Efficiency: Replacing three separate mechanisms with one reduces costs by ~15% (85% of conventional phase-separated designs) while increasing sales value by 1.5x due to enhanced reliability.

Type Testing

• Standards: Compliant with DL/T593, GB1984, IEC62271-100.

• Key Tests:

• Dynamic/thermal stability: 50kA for 3s; 125kA for 0.3s

• Terminal fault tests (T100s): 50kA

• Mechanical life: Successfully completed 5000 cycles

• IP rating: Mechanism box passes protection level tests.

Conclusion

The developed three-phase mechanical linkage system for 252kV tank-type SF₆ circuit breakers addresses critical reliability issues in high-voltage grids. By eliminating phase synchronization errors and reducing component count, this innovation enhances grid stability while achieving cost savings. With international leading technical standards and independent intellectual property rights, this solution fills a domestic technological gap, providing robust equipment support for China's power grid expansion and offering broad market prospects, including potential applications in hybrid switchgear systems.