littelfuse.com

Rev: 063014

1 of 10

MEDIUM VOLTAGE FUSES

2,400-38,000 VAC • Current-Limiting

Bolt-in Mount Fuses

Description

voltage fuses for the protection of transformers, potential

transformers, feeders, and motor circuits. Single, double,

and triple barrel designs are available to cover a wide range

of current, voltage, and interrupting ratings. Conventional

ferrule type, clip lock, and bolt-in mounting configurations

are available for virtually any application. Hermetically sealed

fuses for use in hazardous environments are also offered.

Contact the factory or your local Littelfuse representative for

additional fuse ratings or custom mounting configurations.

24-Hour Emergency Service - Call 800-227-0029

Applications

• Power Transformer Protection

• Potential Transformer Protection

• Motor Controller Back-up Protection

• Fused Switches

• Feeder Circuits

General Information

The terms “Medium Voltage” and “High Voltage” have been

used interchangeably by many people to describe fuses

operating above 600 volts. Technically speaking, medium

voltage fuses are those intended for the voltage range from

2,400 to 38,000 Vac. High voltage fuses are for circuits

carrying voltages greater than 38,000 Vac.

E-rated fuses are considered to be general purpose fuses

and can be used to protect against low and high values

of fault current. R-rated fuses are designed for back-up

protection. They must be used in series with other devices

such as motor overload relays in order to achieve both

overload and short-circuit protection.

Medium voltage fuses are not intended to provide overload

protection in the same sense as fuses rated 600 volts or

less. Medium voltage fuse current ratings do not have the

same meanings as the ampere ratings of low voltage fuses.

All medium voltage fuses are limited in their ability to

interrupt low value overcurrents, especially those between

100% and 200% of the fuse’s continuous current rating.

They are designed to carry their rated current without

exceeding the temperature rise permitted by NEMA and

ANSI standards.

Current-limiting E- and R-rated

fuses are equipped with a

mechanical indicator or striker pin

that protrudes through the fuse

cap upon operation of the fuse.

This provides visual identification

of a blown fuse and can be used

as a trigger for external devices.

extension force 2 lb. minimum.