KYN28 Switchgear: Why Pressure Relief Channels Are Located at the Top of the Enclosure？

1. Core Issue: The Pressure Relief Logic During Internal Arc Faults

When an internal short-circuit arc fault occurs in a KYN28 switchgear (armored, withdrawable, metal-enclosed switchgear), the arc temperature can exceed 10,000°C, instantly generating a massive volume of high-temperature, high-pressure gases. The location of the pressure relief channels directly determines whether the fault energy can be safely and rapidly released — a critical assessment point for internal arc fault (IAC class) performance as mandated by IEC 62271-200 and GB/T 3906-2020.

Locating the pressure relief channels at the top of the enclosure represents the optimal engineering solution based on the following integrated technical considerations.

Rockwill KYN28 Indoor metal-clad air-insulated withdrawable switchgear

2. Five Technical Rationales for Top-Mounted Pressure Relief

2.1 Alignment with the Natural Buoyancy of Hot Gases

High-temperature gases generated by an arc fault have a significantly lower density than the surrounding cooler air and rise rapidly under buoyancy forces. Top-mounted pressure relief channels follow this natural flow direction, discharging high-pressure gases out of the enclosure via the shortest possible path, thereby substantially reducing both the peak internal pressure and its duration.

In the Rockwill KYN28 switchgear, dedicated directional pressure relief flaps are installed at the top of both the busbar compartment and the circuit-breaker compartment, ensuring that relief gases are directed upward along predetermined paths and preventing uncontrolled dispersion.

KYN28 Switchgear Structural Diagram

2.2 Personnel Safety Protection

During normal operation and maintenance, personnel activity is concentrated in front of and alongside the enclosure. Top relief directs explosive gas flows upward into unoccupied areas, aligning with the standard requirement that pressure relief directions must not endanger personnel.

The Rockwill KYN28 switchgear achieves an enclosure protection rating of IP4X, while the enclosure is partitioned by metal barriers into four independent compartments — busbar, circuit-breaker, cable, and low-voltage compartments. Should an internal arc fault occur in any one compartment, the metallic barriers prevent arc propagation into adjacent compartments, working in conjunction with top pressure relief to achieve targeted energy discharge.

2.3 Optimal Utilization of Enclosure Structural Strength

• The top of the enclosure does not house operating mechanisms or major electrical components, making it structurally more suitable for a controlled pressure relief surface.

• The front face of the enclosure accommodates instrument doors, operating handles, and protection relays, which are unsuitable locations for relief openings.

• The Rockwill KYN28 switchgear features a fully metal-armored, welded construction using high-grade cold-rolled steel plates, providing high structural rigidity. The top pressure relief covers are designed with precisely calculated relief areas and flap opening thresholds, ensuring that they open reliably when internal pressure reaches critical levels — achieving controlled pressure relief rather than enclosure rupture.

2.4 Compatibility with Front-Access Maintenance Design

To accommodate wall-mounted installation scenarios, the KYN28 switchgear must support front-access maintenance. The Rockwill KYN28 switchgear incorporates a dedicated current-transformer arrangement that allows operators to perform routine inspections and maintenance from the front of the enclosure, eliminating the need for rear access space.

The top pressure relief channels and the front maintenance access are entirely independent — the relief outlets are overhead, while the service corridor is in front, with no spatial interference — a particularly important consideration in compact substation layouts.

2.5 Coordinated Pressure Relief in Multi-Unit Parallel Arrangements

In substation and industrial distribution systems, KYN28 switchgear is frequently deployed in multiple parallel units. The busbar compartment pressure relief channels in the Rockwill KYN28 switchgear support a through-design configuration, allowing relief gases from adjacent units to be discharged uniformly upward through interconnected top channels. This design prevents inter-unit arc flashover and prevents a fault from propagating from a single unit to the entire switchgear lineup.

3. Summary

Top-mounted pressure relief represents the optimal engineering design for KYN28 switchgear, holistically balancing arc physics, personnel safety, structural feasibility, and regulatory compliance. Building upon this design foundation, the Rockwill KYN28 switchgear translates this advantage into reliable engineering practice through its metal-armored four-compartment construction, directional pressure relief flaps, IP4X protection rating, and broad compatibility with globally prevalent circuit breakers — delivering safe and flexible power distribution solutions for power infrastructure worldwide.
Edied From:Garca