Overview
S&C Electric SM-4 Type SM 125E 34.5kV fuses are precision-engineered refill units designed for protecting critical electrical infrastructure in outdoor distribution substations. The SM-4 Type SM 125E is rated at 125 amperes and engineered for reliable operation through 34.5 kV systems. This refill unit replaces spent fuses in existing SM-4 mounting hardware, making it a cost-effective solution for maintaining system protection without replacing the entire fuse assembly.
Key Features
- 125-ampere rating for precise coordination and protection matching
- Precision-engineered fusible elements — silver or nickel-chrome construction for nondamageable, permanently accurate time-current characteristics
- High fault-interrupting capacity — rated up to 15,600 amperes symmetrical for reliable fault clearing
- Multiple speed options — available in S&C Standard, Slow, and Coordinating speeds for optimized system coordination
- Ideal for transformer and cable protection in outdoor distribution systems, capacitor banks, and substation installations
Technical Specifications
- Product Type: Refill Unit / Replacement Fuse
- Ampere Rating: 125E (125 amperes)
- Voltage Rating: 34.5 kV nominal / 38 kV maximum
- Continuous Current Rating: 200 amperes (SM-4 assembly)
- Interrupting Rating: Up to 15,600 amperes symmetrical at 60 Hz
- Fusible Element Material: Silver or nickel-chrome (nondamageable)
- Application: Outdoor distribution substations, transformer protection, cable circuits, capacitor banks
- Compatibility: SM-4 power fuse mounting hardware
- Standards Compliance: ISO 9001:2000 certified manufacturing
- Quantity: 3 units per lot
Typical Applications
S&C Electric SM-4 Type SM 125E fuses are widely deployed in utility and industrial power systems for:
- Distribution transformer protection in substations rated 4.16 kV through 34.5 kV
- Power cable circuit protection to prevent cascading failures
- Capacitor bank protection in reactive power compensation systems
- System coordination where rapid, reliable fault isolation is required
- Outdoor substations where precision and permanent coordination accuracy are essential
Compatibility & Replacements
Compatible With
- SM-4 power fuse mounting hardware and assemblies
- SM-4 refill unit receptacles and connectors
- S&C standard, slow, and coordinating speed ratings
- Distribution substations rated 4.16 kV through 34.5 kV systems
- Coordination with upstream source-side protective devices
Replaces / Drop-In Replacement For
- S&C Electric 134200R4 (SM-4, 125E, 34.5 kV, Standard Speed)
- S&C Electric 264200R4 (SM-4, 125E, 34.5 kV, Slow Speed)
- Other expired or spent SM-4 Type SM 125E 34.5 kV refill units
Works With
- S&C Electric power fuse product family (SM-4, SM-5, SMD series)
- Outdoor distribution protection coordination systems
- Substation SCADA and monitoring integration
- Utility and industrial power management systems
