Bussmann
®
Circuit Protection Solutions
Bussmann
®
Worldwide Circuit Protection Solutions
World’s leading supplier of fuses and fusible protection
systems, Bussmann continues its 88-year history of blazing new
trails of innovative technologies. Maker of the industry’s first
truly global product line, each item is backed by an efficient
worldwide network of distribution, customer service and
technical support. Bussmann products include the most
extensive circuit protection solutions approved for use in
a variety of major standards: UL, CSA, IEC. . . Not to
mention both European (DIN, British Standard) and
North American styled fuses for a wide range of
applications: industrial motor protection, power
conversion, medium voltage, power distribution,
telecommunications network equipment, electronics,
and automotive. Manufacturing operations in the U.S.,
Denmark, and the United Kingdom have earned ISO
9000 certification. Bussmann customers are assured
of only the utmost quality across every product line.
Knowledgeable. Responsive. Customer focused.
Bussmann continues to set the standard for circuit
protection solutions around the world.
This catalog is intended to present product data and provide technical information that will
help the end user with design application. Bussmann reserves the right, without notice,
to change design or construction of any products and to discontinue or limit distribution
of any products. Bussmann also reserves the right to change or update, without notice,
any technical information contained in this catalog. Once a product has been selected, it
should be tested by the user in all possible applications.
©2002 Cooper Bussmann
Printed in the U.S.A.
®
Bussmann
Section Guide
Page
1
Electrical – Power Fuses
1
2
Electronic – PC Board and Small Dimension Fuses
29
3
Fuseblocks and Holders
41
4
Disconnect Switches
99
5
High Speed Fuses
123
6
Medium Voltage Fuses and Fuse Links
157
7
Telecommunications Protection
175
8
British, European, & Canadian Standard Industrial Fuses
189
9
Fuse Accessories, Displays, Kits, Etc.
202
10
Fuse Technology
210
Glossary of Terms
Index
231
233
Now you can get current information about Bussmann products at anytime,
using BIF (Bussmann Information FAX) or visit us on the World Wide Web.
Bussmann
Information Fax ~
636.527.1450
Bussmann
Worldwide Web ~
BIF is a simple to use automated fax response system. All you need is a touchtone telephone and a fax machine to get complete product specifications when
you want it. Data sheet numbers are located throughout this catalog. To get a
detailed data sheet on the product of your choice, simply dial 636-527-1450
and request the document number listed. In a matter of minutes a data sheet
will be faxed to you. It’s that simple.
Data sheets can also be downloaded from the Internet. The Bussmann web site
is continuously updated with our newest products and latest data on circuit protection solutions. Visit us often at http://www.bussmann.com
http://www.bussmann.com
©2002 Cooper Bussmann
Printed in U.S.A.
i
Bussmann®
General Data – Dimensions (Inches)
CLASS T
CLASS J
CLASS RK5 & RK1
T-Tron™ Fuses
JJN (300V)
JJS (600V)
Low-Peak® & Limitron® Fuses
LPJ & JKS (600V)
Fusetron®, Low-Peak® &
Limitron® Fuses (250V & 600V)
FRN-R & FRS-R; LPN-RK &
LPS-RK; KTN-R & KTS-R
Basic dimensions are same as Class H (formerly NEC) ONE-TIME (NON & NOS) and
SUPERLAG Renewable RES & REN fuses.
NOTE: These fuses can be used to replace
existing Class H, RK1 and RK5 fuses relating
to dimensional compatibility.
A
B
250V
Ampere
⁄Ω¡º-30
35-60
A
2∑
3∑
600V
B
.56∑
.81∑
A
5∑
5.5∑
B
.81∑
1.06∑
A
B
Fusetron & Limitron
250V
Ampere
70-100
110-200
225-400
450-600
A
5.88∑
7.13∑
8.63∑
10.38∑
B
1.06∑
1.56∑
2.06∑
2.59∑
600V
A
7.88∑
9.63∑
11.63∑
13.38∑
B
1.34∑
1.84∑
2.59∑
3.13∑
Low-Peak
250V
Ampere
70-100
110-200
225-400
450-600
A
5.88∑
7.13∑
8.63∑
10.38∑
B
1.16∑
1.66∑
2.38∑
2.88∑
600V
A
7.88∑
9.63∑
11.63∑
13.38∑
B
1.16∑
1.66∑
2.38∑
2.88∑
CLASS L
Low-Peak® & Limitron® Fuses
KRP-C, KTU, & KLU (601 - 6000A) (600V)
NOTE: KRP-CL (150A to 600A) fuses
have same dimensions as 601A to
800A case size. KTU (200A to 600A)
have same dimensions, except tube
3∑ lgth. ≈ 2∑ dia.; terminal 1fi/•∑ width
≈ 1⁄/¢∑ thick.
2
Bussmann®
General Data – Dimensions (Millimeters)
CLASS T
CLASS J
CLASS RK5 & RK1
T-Tron™ Fuses
JJN (300V)
JJS (600V)
Low-Peak® & Limitron® Fuses
LPJ & JKS (600V)
Fusetron®, Low-Peak® &
Limitron® Fuses (250V & 600V)
FRN-R & FRS-R; LPN-RK &
LPS-RK; KTN-R & KTS-R
Basic dimensions are same as Class H (formerly NEC) ONE-TIME (NON & NOS) and
SUPERLAG Renewable RES & REN fuses.
NOTE: These fuses can be used to replace
existing Class H, RK1 and RK5 fuses relating
to dimensional compatibility.
A
B
250V
Ampere
⁄Ω¡º-30
35-60
A
50.8
76.2
B
14.3
20.6
600V
A
127.0
139.7
B
20.6
27.0
A
B
Fusetron & Limitron
250V
Ampere
70-100
110-200
225-400
450-600
A
149.2
181.0
219.1
263.5
B
26.9
39.6
52.3
65.8
600V
A
200.0
244.5
295.3
339.7
B
34.0
46.7
65.8
79.5
Low-Peak
250V
Ampere
70-100
110-200
225-400
450-600
A
149.2
181.0
219.1
263.5
B
29.5
42.2
60.5
73.2
600V
A
200.0
244.5
295.3
339.7
B
29.5
42.2
60.5
73.2
CLASS L Low-Peak® & Limitron® Fuses
KRP-C, KTU, & KLU (601 - 6000A) (600V)
NOTE: KRP-CL (150A to 600A) fuses
have same dimensions as 601A to
800A case size. KTU (200A to 600A)
have same dimensions, except tube
76.2mm lgth. x 50.8mm dia.; terminal
41,3mm width x 31.8mm thick.
3
Bussmann®
Electrical - Power Fuses
Low-Peak® Dual-Element, Time-Delay, Class J Fuses
LPJ_SP
600A
400A
125A
200A
250A
60A
80A
100A
30A
15A
10A
6A
3A
AMPERE
RATING
TIME IN SECONDS
1A
Time-Current Classification Curves—Average Melt
Dual-Element,
Time-Delay –
300
10 seconds (minimum) at
200
500% rated current
100
Ampere Ratings:
1-600A
Voltage Rating:
600Vac (or less),
300Vdc (or less)
10
Current Limiting
Interrupting Rating:
ac – 300,000A RMS Sym. dc – 100,000A
Agency Information:
UL Listed - Special Purpose**, Guide JFHR, File E56412
1
CSA Certified (200,000 AIR) Class J per CSA-22.2 No. 248.8,
Class 1422-02, File 53787
Dimensions: See pages 2-3 for Class J dimensional data.
Catalog Numbers
LPJ-2⁄Ω¢SP
LPJ-8SP
LPJ-50SP
LPJ-250SP
LPJ-2⁄Ω™SP
LPJ-9SP
LPJ-60SP
LPJ-300SP
LPJ-2°Ω¡ºSP
LPJ-10SP
LPJ-70SP
LPJ-350SP
LPJ-3SP
LPJ-12SP
LPJ-80SP
LPJ-400SP
LPJ-3¤Ω¡ºSP
LPJ-15SP
LPJ-90SP
LPJ-450SP
LPJ-3⁄Ω™SP
LPJ-17⁄Ω™SP
LPJ-100SP
LPJ-500SP
LPJ-4SP
LPJ-20SP
LPJ-110SP
LPJ-600SP
**Meets all performance requirements of UL Standard 248-8 for Class J fuses.
Available with silver plated terminals. Add SP/ in front of part number.
Carton Quantity and Weight
Ampere
Ratings
Weight*
Carton
Qty.
Lbs.
Kg.
0-30
10
1.09
0.49
35-60
10
1.78
0.81
70-100
5
1.69
0.77
110-200
5
4.21
1.91
225-400
1
1.67
0.76
450-600
1
2.80
0.27
*Weight per carton.
Recommended fuseblocks/fuseholders for
Class J 600V fuses
• Open fuseblocks - see pages 53-55
• Finger-safe fuseholders for 30A & 60Asee pages 57-58
• Modular fuseblocks - see page 67
.01
10,000
LPJ-225SP
CURRENT IN AMPERES
Current Limitation Curves
LPJ Current Limitation Curves
B
100,000
600A
400A
200A
100A
60A
10,000
30A
15A
AMPERE
RATING
LPJ-45SP
1,000
A
100
200,000
LPJ-7SP
300,000
LPJ-200SP
LPJ-2SP
100,000
LPJ-175SP
LPJ-40SP
1,000
LPJ-35SP
LPJ-6SP
10,000
LPJ-5flꭧSP
LPJ-1°Ω¡ºSP
100
LPJ-1flꭧSP
.1
1,000
LPJ-150SP
10
LPJ-125SP
LPJ-30SP
100
LPJ-25SP
LPJ-5SP
1
LPJ-4⁄Ω™SP
LPJ-1⁄Ω¢SP
INSTANTANEOUS PEAK LET-THRU CURRENT IN AMPS
LPJ-1SP
PROSPECTIVE SHORT-CIRCUIT CURRENT
SYMMETRICAL RMS AMPS
CE logo denotes compliance with European Union Low Voltage Directive
(50-1000Vac, 75-1500Vdc). Refer to Data Sheet: 8002 or contact
Bussmann Application Engineering at 636-527-1270 for more information.
Data Sheet: 1006 (0-60) and 1007 (70-600)
For complete specification data, call Bussmann Information Fax ~ 636.527.1450
17
Bussmann®
Electrical - Power Fuses
Limitron® Quick Acting, Class J Fuses
JKS
Recommended fuseblocks/fuseholders for
Class J 600V fuses
• Open fuseblocks - see pages 53-55
• Finger-safe fuseholders for 30A & 60Asee pages 57-58
• Modular fuseblocks - see page 67
Quick Acting
Ampere Ratings: 1-600A
Voltage Rating: 600Vac (or less)
Current Limiting
Interrupting Rating: 200,000A RMS Sym.
Agency Information: Std. 248-8, Class J
UL Listed, Guide JDDZ, File E4273
CSA Certified, Class 1422-02, File 53787
Dimensions: See pages 2-3 for Class J dimensional data.
Catalog Numbers
JKS-1
JKS-15
JKS-70
JKS-225
JKS-2
JKS-20
JKS-80
JKS-250
JKS-3
JKS-25
JKS-90
JKS-300
JKS-4
JKS-30
JKS-100
JKS-5
JKS-35
JKS-110
JKS-6
JKS-40
JKS-125
Fuse Reducers for J Dimension Fuses
JKS-350
Clip
Size
60A
Fuse
Size
30A
Cat.
No.
(Pair)
J63
Weight
Carton*
(lbs)
0.38
Clip
Size
400A
Fuse
Size
100A
Cat.
No.
(Pair)
J41
JKS-400
100A
30A
J13
1.73
400A
200A
J42
2.75
JKS-450
100A
60A
J16
1.85
600A
400A
J64
3.55
200A
J62
3.55
—
—
JKS-8
JKS-45
JKS-150
JKS-500
200A
60A
J26
2.55
600A
JKS-10
JKS-50
JKS-175
JKS-600
200A
100A
J21
1.36
—
JKS-12
JKS-60
JKS-200
*Carton quantity—10 pair.
Carton Quantity and Weight
Ampere
Ratings
1-30
35-60
70-100
110-200
225-400
450-600
Carton
Qty.
10
10
5
1
1
1
Weight*
Lbs.
0.95
1.175
0.28
0.86
1.78
3.07
Kg.
0.43
0.53
0.13
0.39
0.81
1.39
*Weight per carton.
CE logo denotes compliance with European Union Low Voltage Directive
(50-1000Vac, 75-1500Vdc). Refer to Data Sheet: 8002 or contact
Bussmann Application Engineering at 636-527-1270 for more information.
Data Sheet: 1026 (1-60A), 1027 (70-600A)
18
For complete specification data, call Bussmann Information Fax ~ 636.527.1450
Weight
Carton*
(lbs)
4.90
—
Fuseblocks, Holders and Terminal Blocks
Bussmann®
Class J Fuseblocks
101-200A
3.1"
.75"
C'Bore
6.125"
7.00"
.31"
.5"
3.06"
3.15"
8.31"
.75"
3"
2"
.344" Dia. hole thru
.750 Dia. c'bore
6.125"
1.69"
.34"
DIA.
.750"
FIGURE 7.
FIGURE 6.
201-400A
10.51"
4"
3"
1.75"
.56"
.625"
3.5"
4.00"
9.00"
6.00"
1"
7.50"
.75"
C'Bore
.34"
DIA.
7.5"
.344" Dia. hole thru
.750 Dia. c'bore
2.00"
.50"
.5"
1.00"
FIGURE 8.
FIGURE 9.
401-600A
4.99"
4"
1.75"
1.125"
4.987"
14.144"
1"
11.00"
.56"
3.25"
.344" Dia.
hole thru
.750 Dia.
c'bore
8.875"
8.875"
2.375"
.75"
C'Bore
.34" Dia.
FIGURE 10.
2.88"
FIGURE 11.
.50"
1.00"
Data Sheet: 1114
54
For complete specification data, call Bussmann Information Fax ~ 636.527.1450
Fuseblocks, Holders and Terminal Blocks
Bussmann®
Class J Fuseblocks
CE logo denotes compliance with European Union Low Voltage Directive
(50-1000 Vac, 75-1500 Vdc). Refer to Data Sheet: 8002 or contact
Bussmann Application Engineering at 314-527-1270 for more information.
JP Series
For use with Class J Fuses
(Bussmann LPJ,JKS).
Pyramid Style Fuseblock
Ampere Rating: 30A
Voltage Rating: 600V
Withstand Rating: 200,000 RMS Sym. Amps
Agency Information:
UL Listed, U.L. 512, Guide IZLT, File E14853
CSA Certified, C22.2 No. 39, Class 4225-04, File 47235
Material: Thermoplastic
UL Flammability: UL 94V0
Dimensional Data
Pyramid® J Fuseblock; 30A, 600V; 3-Pole; Panel or 35mm
DIN-Rail Mount; Clips with Reinforcing Springs
Mounting
Panel
With
DIN-Rail
Adapter*
Screws with
Pressure
Plate
JP60030-3PR
(#10-14 CU ONLY)
JP60030-3PRA
(#10-14 CU ONLY)
Catalog Numbers
Box
Aluminum
JP60030-3CR
(#2-14 CU/AL)
JP60030-3CRA
(#2-14 CU/AL)
Copper
Only
JP60030-3COR
(#2-14 CU ONLY)
JP60030-CORA
(#2-14 CU ONLY)
*Adapter Only for DIN-Rail - Cat No. JPA-3.
*All other dimensions (± 0.015∑)
(± 0.40mm)
DIN-RAIL MOUNTING SCREW 8" (203.2mm) APART
END STOPS - PREVENT BLOCK MOVEMENT WHEN CHANGING FUSES
4.00" MAX.
(101.6mm)
2.78"
3.06"
3.75" (±0.02)
(70.6mm)
(77.8mm)
(95.3mm (±0.50)
1.88"
(47.6mm)
3.13"
(79.5mm)
1.19"
ADAPTOR FOR 35mm
SYMMETRICAL DIN-RAIL MOUNTING
(30.2mm)
2.38"
(60.4mm)
3.29"
(83.6mm)
Data Sheet:1108
For complete specification data, call Bussmann Information Fax ~ 636.527.1450
55
Fuseblocks, Holders and Terminal Blocks
Bussmann®
Semiconductor Fuseblocks
J70100
Amps
Ampere Rating: 100A
Voltage Rating: 700V
Agency Information:
UL Recognized, Guide IZLT2, File E14853
Withstand Rating: 200,000 RMS Sym. Amps
For use with 22 ≈ 58mm fuses
(FWP-40A22F, FWP-100A22F, etc.)
Materials: Thermoplastic
UL Flammability: UL 94V0
Poles
1
2
3
100
Catalog Numbers
Box Lug w/
Fig.
Wire
Retaining Clip
No.
Range
J70100-1CR
1
#2-14 CU/AL
J70100-2CR
2
#2-14 CU/AL
J70100-3CR
3
#2-14 CU/AL
Dimensional Data
100A
1.702
3.202
.750
2.250
2.415
4.702
2.250
.750
4.005
C
L
CL
1.500
FIGURE 1
FIGURE 2
FIGURE 3
Data Sheet: 1211
56
For complete specification data, call Bussmann Information Fax ~ 636.527.1450
Fuseblocks, Holders and Terminal Blocks
Bussmann®
Class J (Finger-Safe) Fuseholders
Safety J
JT(N)60030 and JT(N)60060
For use with Bussmann Class “J” fuses - (Bussmann LPJ, JKS)
Catalog Numbers:
JT60030 and JT60060 - Non-Indicating
JTN60030 and JTN60060 - Indicating (Neon)
Construction: Thermoplastic, UL Flammability; 94VO
Voltage Ratings: 600V
Amperage Rating: JT(N)60030 - 30A,
JT(N)60060 - 60A
Withstand Rating: 200,000A RMS Sym.
(Self Certified at 300,000A using Bussmann
LPJ_SP fuses)
Agency Information:
Listed to UL 512: Guide IZLT, File 14853
CSA Certified: Class 6225-01, File 47235
1.14
(29.0)
Indication: Min. voltage: 90 VAC, 115 VDC; Neon Lamp
“ON” when fuse opens, voltage source and current path
are present.
Finger-Safe: IP20 per IEC 60529
Terminations: 30A Dual Port Torque 20 lb. in.,
60A Single Port Torque 45 lb. in., Terminal Construction,
Tin plated Copper Alloy
Wire Size: JT(N)60030 - Rated for 75°C, AWG#18-#8;
CU only, JT(N)60060 - Rated for 75°C, AWG#14-#4;
CU only.
(Note: For JT(N)60030 use both stranded or solid, in a variety of
dual wire combinations of same wire size and type.)
Packaging: 12 in a carton
CE logo denotes compliance with European Union Low Voltage Directive
(50-1000Vac, 75-1500Vdc). Refer to Data Sheet: 8002 or contact
Bussmann Application Engineering at 636-527-1270 for more information.
1.05
(26.7)
Slot
Din-rail
.07
(1.8)
MOUNTING
Shown without fuse
pullout cover
Dim. =
in.
(mm.)
2.75
(69.9)
1 pole
2 pole
3 pole
BUSS
BUSS
BUSS
JT60030
0 – 30A
600VAC
JT60030
0 – 30A
600VAC
JT60030
0 – 30A
600VAC
USE CLASS J
FUSES
USE CLASS J
FUSES
USE CLASS J
FUSES
DO NOT REMOVE
UNDER LOAD
DO NOT REMOVE
UNDER LOAD
DO NOT REMOVE
UNDER LOAD
1.23
(31.2)
2.42
(61.3)
3.60
(91.4)
2.52
(64.1)
JT60030
JTN60030
Data Sheet: 1152
For complete specification data, call Bussmann Information Fax ~ 636.527.1450
57
Fuseblocks, Holders and Terminal Blocks
Bussmann®
Class J (Finger-Safe) Fuseholders
JT(N)600 Series fuseblocks can be dovetailed together within the same current rating to provide multiple pole block
configurations.
NOTE: JT(N)60030 cannot be dovetailed to JT(N)60060.
1.31
(33.3)
1.25
(31.8)
Slot
Din-rail
.10
(2.6)
3.10
(78.7)
1 pole
2 pole
3 pole
MOUNTING
BUSS
BUSS
BUSS
JT60060
35 – 60A
600VAC
JT60060
35 – 60A
600VAC
JT60060
35 – 60A
600VAC
USE CLASS J
FUSES
USE CLASS J
FUSES
USE CLASS J
FUSES
DO NOT REMOVE
UNDER LOAD
DO NOT REMOVE
UNDER LOAD
DO NOT REMOVE
UNDER LOAD
1.52
(38.1)
2.96
(75.2)
4.40
(111.7)
Shown without fuse
pullout cover
Dim. =
in.
(mm.)
JT60060
JTN60060
3.06
(77.7)
Data Sheet: 1152
58
For complete specification data, call Bussmann Information Fax ~ 636.527.1450
Time-Current & Current Limitation Curves
Bussmann®
LPJ (600V), Class J Fuses
.1
AMPERE
RATING
A
100
200,000
1
1,000
100,000
TIME IN SECONDS
10
10,000
10,000
100
600A
400A
200A
100A
60A
50A
40A
30A
20A
15A
LPJ
1,000
LPJ
B
100,000
100
AMPERE
RATING
INSTANTANEOUS PEAK LET-THRU CURRENT IN AMPS
600A
Current Limitation Curves
10A
15A
20A
30A
40A
50A
60A
100A
125A
200A
225A
400A
5A
3A
300
1A
Time-Current Characteristic Curves—
Average Melt
10,000
1,000
100
1
.01
10
PROSPECTIVE SHORT-CIRCUIT CURRENT
SYMMETRICAL RMS AMPS
RMS SYMMETRICAL CURRENT IN AMPERES
227
Glossary of Terms
Ampere
The measurement of intensity of rate of flow of
electrons in an electric circuit. An ampere is
the amount of current that will flow through a
resistance of one ohm under a pressure of one
volt.
Ampere Rating
The current-carrying capacity of a fuse. When
a fuse is subjected to a current above its
ampere rating, it will open the circuit after a
predetermined period of time.
Ampere Squared Seconds, l2t
The measure of heat energy developed within
a circuit during the fuse’s clearing. It can be
expressed as “melting l2t”, “arcing l2t” or the
sum of them as “Clearing l2t”. “l” stands for
effective let-through current (RMS), which is
squared, and “t” stands for time of opening, in
seconds.
Arcing Time
The amount of time from the instant the fuse
link has melted until the overcurrent is interrupted, or cleared.
Breaking Capacity
(See Interrupting Rating)
Cartridge Fuse
A fuse consisting of a current responsive element inside a fuse tube with terminals on both
ends.
Class CC Fuses
600V, 200,000A interrupting rating, branch
circuit fuses with overall dimensions of ⁄‹Ω£™∑ ≈
1⁄Ω™∑. Their design incorporates a rejection
feature that allows them to be inserted into
rejection fuse holders and fuse blocks that
reject all lower voltage, lower interrupting rating ⁄‹Ω£™∑ ≈ 1⁄Ω™∑ fuses. They are available from
⁄Ω¡ºA through 30A.
Class G Fuses
480V, 100,000A interrupting rating branch circuit fuses that are size rejecting to eliminate
overfusing. The fuse diameter is ⁄‹Ω£™∑ while
the length varies from 1fiΩ¡§∑ to 2⁄Ω¢∑. These are
available in ratings from 1A through 60A.
Class H Fuses
250V and 600V, 10,000A interrupting rating
branch circuit fuses that may be renewable or
non-renewable. These are available in ampere
ratings of 1 amp through 600A.
Class J Fuses
These fuses are rated to interrupt a minimum
of 200,000A ac. They are labelled
as “Current-Limiting”, are rated for 600vac,
and are not interchangeable with other classes.
Bussmann®
Class K Fuses
These are fuses listed as K-1, K-5, or K-9
fuses. Each subclass has designated I2t and lp
maximums. These are dimensionally the same
as Class H fuses, and they can have interrupting ratings of 50,000, 100,000, or 200,000 A.
These fuses are current-limiting. However,
they are not marked “current-limiting” on their
label since they do not have a rejection feature.
Class L Fuses
These fuses are rated for 601 through 6000A,
and are rated to interrupt a minimum of
200,000A ac. They are labelled “CurrentLimiting” and are rated for 600Vac. They are
intended to be bolted into their mountings and
are not normally used in clips. Some Class L
fuses have designed in time-delay features for all
purpose use.
Class R Fuses
These are high performance fuses rated ⁄Ω¡º600A in 250V and 600V ratings. All are
marked “Current Limiting” on their label
and all have a minimum of 200,000A interrupting rating. They have identical outline
dimensions with the Class H fuses but have a
rejection feature which prevents the user from
mounting a fuse of lesser capabilities (lower
interrupting capacity) when used with special
Class R Clips. Class R fuses will fit into either
rejection or non-rejection clips.
Class T Fuses
An industry class of fuses in 300V and 600V
ratings from 1 amp through 1200A. They are
physically very small and can be applied
where space is at a premium. They are fast
acting and time-lag fuses, with an interrupting
rating of 200,000A RMS.
Classes of Fuses
The industry has developed basic physical
specifications and electrical performance
requirements for fuses with voltage ratings of
600V or less. These are known as standards.
If a type of fuse meets the requirements of a
standard, it can fall into that class. Typical
classes are K, RK1, RK5, G, L, H, T, CC, and J.
Clearing Time
The total time between the beginning of the
overcurrent and the final opening of the circuit
at rated voltage by an overcurrent protective
device. Clearing time is the total of the melting time and the arcing time.
Current Limitation
A fuse operation relating to short circuits only.
When a fuse operates in its current-limiting
range, it will clear a short circuit in less than ⁄Ω™
cycle. Also, it will limit the instantaneous peak
let-through current to a value substantially
less than that obtainable in the same circuit if
that fuse were replaced with a solid conductor of equal impedance.
Dual Element Fuse
Fuse with a special design that utilizes two
individual elements in series inside the fuse
tube. One element, the spring actuated trigger assembly, operates on overloads up to
5-6 times the fuse current rating. The other
element, the short circuit section, operates on
short circuits up to their interrupting rating.
Electrical Load
That part of the electrical system which actually uses the energy or does the work
required.
Fast Acting Fuse
A fuse which opens on overload and short
circuits very quickly. This type of fuse is not
designed to withstand temporary overload
currents associated with some electrical
loads.
Fuse
An overcurrent protective device with a fusible
link that operates and opens the circuit on an
overcurrent condition.
High Speed Fuses
Fuses with no intentional time-delay in the
overload range and designed to open as
quickly as possible in the short-circuit range.
These fuses are often used to protect solidstate devices.
Inductive Load
An electrical load which pulls a large amount
of current—an inrush current—when first
energized. After a few cycles or seconds the
current “settles down” to the full-load running
current.
Interrupting Capacity
See Interrupting Rating
Interrupting Rating
(Breaking Capacity)
The rating which defines a fuse’s ability to
safely interrupt and clear short circuits. This
rating is much greater than the ampere rating
of a fuse. The NEC® defines Interrupting
Rating as “The highest current at rated voltage that an overcurrent protective device is
intended to interrupt under standard test
conditions.”
Melting Time
The amount of time required to melt the fuse
link during a specified overcurrent. (See
Arcing Time and Clearing Time.)
“NEC” Dimensions
These are dimensions once referenced in the
National Electrical Code. They are common to
Class H and K fuses and provide interchangeability between manufacturers for
fuses and fusible equipment of given ampere
and voltage ratings.
Ohm
The unit of measure for electric resistance. An
ohm is the amount of resistance that will allow
one ampere to flow under a pressure of one
volt.
231