Next
Medium Voltage Fuses
ꢀ
2400 - 25,500 VAC Current Limiting
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.
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 pro-
tection. 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.
Littelfuse now offers a complete selection of “E” and “R”
rated medium voltage fuses for the protection of trans-
formers, 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 now available for virtually any
application. Hermetically sealed fuses for use in hazardous
environments are also offered.
All medium voltage fuses are limited in their ability to inter-
rupt 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.
Additional application data can be found in the Fuse
Application section of the POWR-GARD Products
catalog (PF101).
Contact the factory or your local Littelfuse representative for
additional fuse ratings or custom mounting configurations.
24 Hour Emergency Service is available.
Call 1-800-227-0029.
APPLICATIONS
ꢀ
Power Transformer
Protection
ꢀ
Potential Transformer
Protection
ꢀ
Motor Controller Back-up
Protection
ꢀ
Fused Switches
ꢀ
Feeder Circuits
Bolt-in Mount Fuses
61