SM4 and SM5 Fuses from S&C Electric
Type SM Fuses are especially suited for protecting transformers, capacitor banks, and cables in outdoor distribution substations on systems rated up through 34.5 kV.
They offer the superior performance characteristics and reliability required to provide twofold protection protection for the system upstream, and protection for downstream equipment.
Type SM Power Fuses from S&C Electric are offered with maximum continuous current ratings of 200, 300, 400, and 720 amperes, and are available with fault-interrupting ratings from 28,000 amperes RMS asymmetrical at 34.5 kV to 60,000 amperes RMS asymmetrical at 4.16 kV.
These power fuses are available in a variety of ampere ratings as well, and in three different speeds: Standard, Slow, and Coordinating. The broad selection of available ampere ratings and speeds permits close fusing to achieve maximum protection and optimum coordination. They may be operated (i.e., opened or closed when not carrying load) using a hookstick or a universal pole equipped with a variety of fuse-handling fittings
Features of S&C SM4 and SM5 Fuses
- Nondamageable silver or nickel-chrome fusible elements
- Provide precise and permanently accurate time-current characteristics
- Permit upstream protective devices to be set for faster operation
- Maximum continuous current ratings of 200, 300, 400, and 720 amperes
Applications of S&C SM4 & SM5 Fuses
- Cables
- High Voltage Capacitors
- Pad Mounted Transformers
Definitions
- The Refill Unit - The refill unit consists of a fusible element, arcing rods, and a solid-material arc-extinguishing medium contained within a filament-wound glass-epoxy tube. The fusible element is connected at one end through a current-transfer bridge to the refill unit lower ferrule. At the other end, the fusible element is connected to the main arcing rod, which extends upward through the main bore of the refill unit to the upper terminal. The auxiliary arcing rod, of stainless steel, is threaded into the upper terminal and extends downward through a small-diameter stepped bore and through an opening in the current-transfer bridge. No load current is carried by this auxiliary rod since, at its small-diameter section, it is insulated from the auxiliary arcing contact.
- Spring-and-cable assembly stainless steel spring provides high-speed elongation of arc within refill unit when fuse operates. Copper cable inside spring carries load (and fault) current
Brands:
- S&C Electric
Data Sheet:
- Data Sheet 3: SM4 and SM5 Fuses
