Medium Voltage Fuses
2400 - 25,500 VAC
s
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.
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).
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.
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
s
s
s
s
s
Power Transformer
Protection
Potential Transformer
Protection
Motor Controller Back-up
Protection
Fused Switches
Feeder Circuits
Bolt-in Mount Fuses
61
R Rated Medium Voltage Fuses
Current Limiting
FEATURES
“R” rated fuses provide required short-circuit protection for
medium voltage motors, motor controllers and associated
circuitry. These components have limited ability to absorb the
energy of large short circuit currents. Medium voltage motor
controllers contain overload relays which provide both over-
load protection and locked rotor protection to the motor. The
controllers are also intended to interrupt low value short cir-
cuits within the capability of the motor controller. This pro-
tects the medium voltage fuse from sustained overcurrents
which are less than their minimum interrupting rating.
NEMA Standards for “R” rated medium voltage power fuses
require that they operate within 15-35 seconds when sub-
jected to an rms current 100 times the “R” rating. For exam-
ple, a fuse with a 2R rating will open within 15 to 35 seconds
on an applied current of 2 x 100 = 200 amperes.
Part Number System
CHARACTERISTICS
Voltage Rating:
2,400 volts – 15,500 volts
Current Range:
2R – 36R
OPTIONS
s
s
s
Hermitically sealed for use in hazardous locations
(add “S” suffix to part number)
Hookeye attachment (add “W” suffix to part number)
Bolt-in mounting configurations
130 - 4R -1C - 5.5
Max Voltage (KV)
Style (C-Cartridge)
No. of Barrels
Rating (size)
Continuous Current
Hookeye
Feature*
*For hookeye attach-
ment; add “W” suffix
to part number
3"DIA
6.38"
9.75"
Dim.A
Clip
Center
Dim.B
FIGURE 1
D
FIGURE 2
DD
FIGURE 3
DDD
R
RATED
Catalog
Number
70-2R-1C-2.75
100-3R-1C-2.75
130-4R-1C-2.75
150-5R-1C-2.75
170-6R-1C-2.75
200-9R-1C-2.75
230-12R-1C-2.75
390-18R-2C-2.75
450-24R-2C-2.75
Old
Catalog
Number
LCK 2R
LCK 3R
LCK 4R
LCK 5R
LCK 6R
LCK 9R
LCK 12R
LCK 18R
LCK 24R
Size
2R
3R
4R
5R
6R
9R
12R
18R
24R
Maximum
Continuous
Current
@ 40 deg C.
70
100
130
150
170
200
230
390
450
Dim. A
(inches)
Dim. B
(inches)
7"
10.875"
7"
10.875"
Minimum
Interrupting
Rating
RMS Amps
170
250
340
390
500
760
1000
1500
1950
Max
Interrupting
Rating
RMS Asym
80,000
80,000
80,000
80,000
80,000
80,000
80,000
80,000
80,000
Figure
Number
1
1
1
1
1
1
1
2
2
Add “w” suffix to part number for hookeye attachment.
62
2.75 KV
MCU
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