Xi'an, China — Recently, Rockwill announced a major technological breakthrough at Xi'an High Voltage Apparatus Research Institute (XIHARI): its independently developed 245kV/50.5kA high-voltage SF₆ circuit breaker has successfully passed the extreme low-pressure, high-current single-phase interruption type test.
Rockwill 245kV/60Hz Circuit Breaker Site Photos
This milestone not only resolves the long-standing challenge of high-severity interruption in 60Hz systems under the U.S. standard but also demonstrates a significant safety margin under extreme conditions at 0.5MPa absolute pressure—close to the blocking threshold. This marks a leap forward for domestically manufactured high-voltage switchgear into the realm of world-class cross-generational technology.
Hardcore Breakthrough: Facing the "Nightmare-Level" Challenge of the 60Hz U.S. Standard
Targeting the stringent requirements of 60Hz power systems in North America, South America, and Saudi Arabia, Rockwill's product underwent extreme testing in XIHARI's Weil synthetic test circuit:
High-Frequency Zero Crossing: Compared to 50Hz systems, the zero-crossing speed of 60Hz AC increases by 20%, compressing the cooling time window for the arc-extinguishing chamber to microseconds, with a di/dt as high as 26.7A/μs.
Ultra-Long Arcing Tolerance: Under a 12.5ms extreme arcing time, the circuit breaker withstood a full-load half-wave impact with a duration of 8.5ms and a peak current of 65.2kA—without thermal breakdown.
Ultimate Touchstone: Insulation Miracle at the Critical Pressure of 0.5MPa
The highlight of this test was the proactive "bottoming out" approach. Building on the successful full-pressure test at 0.6MPa last year, Rockwill deliberately reduced the SF₆ pressure to 0.5MPa (gauge pressure 0.4MPa)—a value generally considered the operational blocking threshold under extremely low pressure:
Despite the significant reduction in gas density, the physical isolation was ensured through an ultra-fast opening speed of 22.4ms.
Successfully withstood the heavy strike of transient recovery voltage (TRV) up to -373kV under XIHARI's 4-parameter TRV control, with no restriking or breakdown—validating exceptional dielectric recovery strength.
Rockwill 245kV/60Hz Circuit Breaker – Testing Site
Cross-Generational Core: Aerodynamics and Arc Control Innovation
Through an innovative arc-extinguishing chamber topology, Rockwill's R&D team broke through the traditional physical bottleneck of "relying on high pressure to maintain insulation":
Forced Deionization Channels: A newly optimized flow field design creates micro-scouring channels for cold SF₆ gas, geometrically enhancing convective heat dissipation under low gas density—achieving deionization capabilities comparable to those at higher pressures.
Ultra-Fast Residue-Free Deionization: Thermal residual plasma and metal vapor are instantly channeled into expansion chambers via dedicated pathways, ensuring the dielectric at the contact gap recovers purity within microseconds, readily handling excessive TRV impacts.
Global Outlook: Unlocking Full Access to High-End Export Markets
The success of this test confirms that Rockwill's 245kV circuit breaker is fully capable of operating under the world's most complex grid conditions:
High Reliability: Abundant safety margins for extreme conditions such as short-line faults (SLF), out-of-phase (OP) switching, and Class C2 capacitive current switching.
Environmental Adaptability: Even under severe cold causing pressure drops or long-term minor leaks, the equipment retains a robust safety barrier—particularly suited for high-altitude and unattended substations.
Market Access: Completely removes technical barriers to entering North American (ANSI/IEEE) and other global high-end markets, setting a new benchmark for Chinese high-end power equipment exports.
About Rockwill:
Rockwill is a globally leading provider of smart grid solutions, specializing in the R&D and manufacturing of high-voltage switchgear and distribution automation systems. The breakthrough achieved with the 245kV product further reaffirms its world-class R&D capabilities in the high-voltage apparatus sector.
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