Littelfuse 700-xxx Series - Manual

© JUNE 2011 Littelfuse POWR-GARD Products www.littelfuse.com
POWR-GARD ® Fuses—Medium Voltage
1
Description
Littelfuse ® offers a 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 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 is available. Call 800-227-0029,
Option 6.
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.
Note: Extension distance 1 /
2 ” minimum;
extension force 2 lb. minimum.
MEDIUM VOLTAGE FUSES
2,400-38,000 VAC • Current-Limiting
Bolt-in Mount Fuses