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Medium-Voltage Fuses

Medium-Voltage
Littelfuse medium volt fuse
Medium-voltage fuses provide protection against short circuits in power transformers and industrial electric motors. The devices are categorized as general-purpose E Rated fuses, backup R Rated fuses that should be paired with overload relays, and Potential Transformer (PT) fuses. Littelfuse produces each type of medium voltage fuse, as well as a full line of specialized fuse clips. Rated at between 600 V ac and 8250 V ac, medium voltage fuses have silver elements, cavities filled with silica sand, and very high interrupting ratings. This makes the fuses slow to blow and highly durable while operating nominally.
  • Rated at 600–8250 V
  • Wide range of interrupting ratings to permit many applications
  • Indicator pins show when E Rated and R Rated fuses blow
  • Meet NEMA and ANSI standards
  • Encapsulated and sealed versions available for hazardous areas where dust or gases could explode due to overcurrent events.
  • Single-, double-, and triple-barreled configurations available
  • Bolt-down and clip lock configurations available
  • Can be ordered with mounting accessories specifically designed for each type of fuse

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Medium voltage fuses are applied quite differently than fuses rated up to 600 V. The biggest difference is that medium voltage fuses are not intended to provide overload protection. They should only be applied in situations where it will not be required to open small overcurrents. Medium voltage fuses offer a much wider range of system voltages, thereby resulting in a correspondingly large number of fuse voltage ratings.

For questions, contact our Technical Support and Engineering Services Group at 1-800-TEC-FUSE (1-800-832-3873).

 

Littelfuse medium voltage fuses are silver element, silica sand, nonexpulsion design, current-limiting type devices. When properly applied, they are designed to carry their nominal current rating continuously without fatigue failure. This means that the fuse will not age, become brittle, or deteriorate under the most severe duty cycling.

When talking current-limiting medium voltage fuses, there are two basic types: general purpose and back-up. General purpose fuses have the ability to interrupt both large and small short-circuits down to currents which would cause the fuse to open within one hour. They are used to provide short-circuit protection for transformers, switchgear, and similar equipment.

Backup fuses are designed to protect only against high fault currents and must be used in series with equipment which provides the circuit’s required overload and low value short-circuit protection.

Medium voltage E-rated fuses are considered general purpose fuses. Their mounting dimensions permit them to be installed in a wide variety of medium voltage switches, in pad-mounted transformers, and at other similar locations. R-rated MV fuses are specifically designed to provide short-circuit protection for medium voltage motor controllers and associated equipment.

Download the Littelfuse white paper on Selecting and Applying Medium Voltage Fuses.