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Views： 2 Author： Mark Zhang Publish Time： 2026-07-03 Origin： 本站
The SN-63 is a low-volt-level molded case circuit breaker from SINGI, designed for efficient overload and short-circuit protection in industrial and commercial power distribution. This article explains its construction, performance characteristics, and typical application scenarios, helping engineers and procurement professionals assess its suitability for their projects.
The SN-63 belongs to the molded case circuit breaker (MCCB) family, offering a rated amperage from 63A up to 630A in various frame sizes. Its key differentiators include a robust arc extinction chamber using deion plates, which allows interruption within 3–5 ms under rated short-circuit conditions. The thermal-magnetic trip unit provides both long-time delay for overload protection and instantaneous trip for short circuits. Unlike miniature circuit breakers (MCBs), the SN-63 can handle higher fault currents up to 50 kA at 415 V AC, making it suitable for main distribution panels and large branch feeders.
In low-volt-level systems, fault currents can exceed 25 kA near transformers or large motors. A breaker with inadequate breaking capacity may fail to interrupt the fault, causing arc flash, equipment damage, or fire. The SN-63 is tested to IEC 60947-2 and provides breaking capacities up to 65 kA in chosen frames, ensuring reliable interruption even in high prospective amperage scenarios. This margin reduces the need for additional current-limiting fuses or series protection, simplifying system design.
Note: Always verify the available fault amperage at the point of installation. The SN-63 offers versions with standard breaking capacity (S), high capacity (H), and very high capacity (V) to match different network conditions.
During a short circuit, the SN-63 employs a rapid contact separation mechanism driven by high electromagnetic repulsion forces. The arc is driven into a stack of steel deion plates where it is stretched, cooled, and extinguished within a half cycle. The resulting let-through energy (I²t) is low, limiting thermal stress on downstream equipment. Trip curves are available in types B, C, D, and K to coordinate with backup breakers or loads such as motors or transformers.
| Parameter | SN-63 (Standard) | SN-63 (High) |
|---|---|---|
| Rated Insulation Volt-level (Ui) | 690 V AC | 690 V AC |
| Rated Operational Volt-level (Ue) | 415 V AC | 415 V AC |
| Breaking Capacity (Icu) at 415 V | 35 kA | 65 kA |
| Mechanical Life | 10,000 cycles | 10,000 cycles |
Choice starts with system volt-level and fault current. Determine the required breaking capacity from a short-circuit study. Choose the frame size based on continuous load amperage (e.g., 63A, 125A, 250A, 630A). The SN-63 offers 3-pole and 4-pole versions, with or without neutral protection. Accessories include shunt trip, undervolt-level release, auxiliary contacts, and motor operators. For remote monitoring, the SN-63 supports communication modules conforming to Modbus RTU.
Always consult the SINGI technical datasheet for specific derating factors due to altitude, ambient temperature, and grouping.
Review the full specifications and order the SN-63 circuit breaker from SINGI.
View SN-63 Product Page
