Customizable LW Series 40.5kV Indoor High-voltage SF6 Circuit Breakers — Overview

The Customizable LW Series 40.5kV Indoor High-voltage SF6 Circuit Breakers from JYDQ are withdrawable handcart-type switching devices for KYN61-40.5 metal-clad switchgear panels. Rated at 40.5kV, 35kV, and 30kV for three-phase AC 50/60 Hz systems, these breakers serve as the primary protection and control element for indoor substation feeders, transformer circuits, bus-tie applications, and capacitor bank switching. Selecting the right high-voltage SF6 circuit breaker for a KYN61-40.5 cubicle demands careful evaluation of fault-level capability, rated current, switching duty, and long-term mechanical endurance—not simply matching the rated voltage.

Two standardized configurations are available: a 1250A / 25kA variant for feeder and transformer protection, and a 1600A / 31.5kA variant for bus-tie, generator circuit, and heavy-fault industrial applications. Both share identical KYN61-40.5 dimensions: 300 mm phase spacing, 400 mm upper-to-lower terminal distance, matching wheel gauge and secondary disconnect positions.

SF6 Arc-Quenching Technology

The Customizable LW Series 40.5kV Indoor High-voltage SF6 Circuit Breakers employ an auto-puffer arc extinction chamber with SF6 gas at a rated absolute pressure of 0.65 MPa at 20°C. A piston driven by the spring operating mechanism compresses SF6 and directs a high-pressure blast across the arcing contacts, extinguishing the arc at the first current-zero crossing. The hermetically sealed interrupter maintains its charge with an annual leakage rate of no more than 1%, and moisture is controlled to under 150 ppm(V) at delivery. A temperature-compensated density relay provides alarm contacts at 0.62 MPa and lock-out contacts at 0.59 MPa, preventing any switching operation under compromised gas conditions. When connecting to primary cables, the sf6 bushing interface must be verified for dimensional compatibility with the panel cable entry before installation.

Key Technical Ratings

From a distribution system design perspective, the two LW Series variants address distinct KYN61-40.5 application requirements. The 25kA variant handles general feeder and transformer duty; the 31.5kA variant serves bus-tie, heavy industrial, and high-fault-level applications:

• Rated voltage: 40.5 kV / 35 kV / 30 kV
• Rated current: 1250 A (25kA variant) / 1600 A (31.5kA variant)
• Short-circuit breaking current: 25 kA / 31.5 kA; making current (peak): 63 kA / 80 kA
• Short-time withstand current (4s): 25 kA / 31.5 kA
• Power frequency withstand voltage: 95 kV; lightning impulse withstand: 185 kV
• Capacitor bank switching current: 800 A (both variants)
• Opening time: ≤0.06 s; closing time: ≤0.15 s
• Mechanical endurance: 6,000 operations; electrical life: 20 operations at rated breaking current
• Rated operating sequence: O-0.3s-CO-180s-CO
• SF6 rated gas pressure: 0.65 MPa absolute (20°C); annual leakage: ≤1.0%
• Weight: approx. 500 kg (25kA) / 600 kg (31.5kA)

Operating Mechanism

The Customizable LW Series 40.5kV Indoor High-voltage SF6 Circuit Breakers use a side-mounted motor-driven stored-energy spring mechanism (AC/DC 220V, 750W). The spring charges within 15 seconds. Closing and opening coils accept DC 220V or DC 110V. Standard equipment includes 8NO + 8NC auxiliary contact pairs, mechanical and electrical anti-pumping interlocks, a non-resettable operation counter, and a hand-crank for emergency manual charging. The ≤0.06 s opening time limits arc energy in transformer protection and arc furnace feeder circuits. Specifying high voltage cable connections requires confirmation of terminal positions and cable lug dimensions against the panel cable compartment layout at the design stage.

Application Scenarios

Indoor Substation Feeder and Transformer Protection

For 35kV/40.5kV indoor metal-clad substations serving industrial parks, commercial complexes, or distribution networks, the Customizable LW Series 40.5kV Indoor High-voltage SF6 Circuit Breakers (1250A/25kA) deliver high-speed fault clearance, O-CO-CO auto-reclose, and 185kV lightning impulse withstand. The shift happens when engineers realize these breakers are rated for standard ambient conditions but their installation involves an enclosed switchgear room in a tropical climate or high-altitude site—altitude correction and cooling margins must be confirmed with the application team before ordering.

Bus-Tie and Heavy Industrial Switching

For bus-tie duties or high-frequency switching in arc furnace supply, rolling mill, and capacitor bank control, the 1600A/31.5kA Customizable LW Series 40.5kV Indoor High-voltage SF6 Circuit Breakers with 6,000-operation mechanical life are the practical choice. The 800A capacitor bank switching rating—double the 400A typical in comparable designs—enables restrike-free service to larger reactive compensation banks. Comparing breakers on rated specifications is straightforward; evaluating supplier application engineering support, spare parts continuity, and type-test documentation over the 25–30 year service life requires more structured assessment.

Competitive Differentiators and Quality Assurance

Double Mechanical Endurance: 6,000 operations—twice the 3,000-operation standard for the 40.5kV class—reduces maintenance frequency for arc furnace, traction, and capacitor bank feeders.

High-Pressure SF6 at 0.65 MPa: Above the 0.45 MPa typical of comparable designs, enhancing dielectric strength and the safe operating window before the 0.59 MPa lock-out threshold.

KYN61-40.5 Interchangeability: Identical panel dimensions allow form-fit-function replacement of legacy breakers without panel or busbar modification.

IEC 62271-100 Certification (KEMA): Manufactured under ISO 9001 and type-tested per IEC 62271-100 and GB 1984 at KEMA-accredited laboratories. Factory acceptance tests on each unit cover power-frequency withstand, lightning impulse withstand, SF6 gas tightness, contact resistance, timing, and partial discharge screening—providing a complete documentation package for grid authority pre-qualification and EPC tender submissions.

Procurement Information

MOQ: 1 set. Delivery: 20–35 working days after deposit. Packaging: vacuum-sealed moisture barrier in export-grade plywood case. Payment: T/T or L/C at sight. FOB: Ningbo or Shanghai. Capacity: 200 sets per month. Applicable standards: IEC 62271-100, GB 1984, IEC 62271-1, GB/T 11022, IEC 62271-200, GB 3906. Brand: JYDQ | Model: LN-40.5 | Origin: Zhejiang, China | Certifications: ISO 9001, KEMA.

FAQ

1. What risk should be noticed during SF6 circuit breaker operation?

The main attention point is gas tightness. Long-term operation may have tiny gas leakage. Continuous gas density monitoring can effectively prevent operation failure.

2. What rated current options are available for SF6 circuit breaker?

The optional rated current includes 1250A, 2000A, 2500A, 3150A and 4000A. We can select suitable specification according to your system load.

3. What solution can you provide for coastal projects?

We adopt heavy anti-corrosion coating on metal shell and structural parts to resist salt fog corrosion, maintaining stable performance under high humidity coastal environment.

4. What warranty service do you provide?

We provide 10 years warranty for all SF6 circuit breakers. Our technical team can remotely guide your team on maintenance precautions during the warranty period.