Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
08/35
08
■Specifications
Rated Rated Peak Max. Watt Fuse-link
current
voltage
arc interrupting I2t loss
voltage
(Amp
2
×sec.)
× 103Type
(A) (V) (W)
12 550V 1550 0.09 5.1 BLC012-1
20 AC 1550 0.27 8.5 BLC020-1
23 1550 0.39 10 BLC023-1
45 1380 1.8 19 BLC045-1
75 1250 5 32 BLC075-1
90 1250 11.5 38 BLC090-1
120 1200 33 51 BLC120-1
140 1200 100 59 BLC140-1
30 250V Max. 0.35 4.0 CR2L-30
50 AC 500 0.85 6.0 CR2L-50
75 2.3 9.0 CR2L-75
100 4.0 12.0 CR2L-100
125 6.5 14.0 CR2L-125
140 7.0 16.0 CR2L-140
150 9.5 18.0 CR2L-150
175 13 21.0 CR2L-175
200 17 23.0 CR2L-200
225 22 26.0 CR2L-225
260 27 30.0 CR2L-260
300 38 35.0 CR2L-300
325 49 37.0 CR2L-325
350 60 37.0 CR2L-350
400 103 39.0 CR2L-400
450 140 46.0 CR2L-450
500 160 48.0 CR2L-500
550 200 51.0 CR2L-550
600 215 56.0 CR2L-600
Interrupting capacity
BLC ...... 100kA at 550V AC
CR2L .... 100kA at 250V AC
BLC, CR and CS types
Super Rapid Fuses
150–1500 Volts AC
10–4700 Amps
■Description
The FUJI BLC, CR and CS types are
extremely reliable fuses which have
been specially developed to provide
protection for silicon diodes and
thyristors and are suitable for inverters
using semiconductors or transformers-
rectifiers. FUJI Super Rapid Fuses are
designed with a very small total I2t
value which gives them a high speed
interrupting action in the face of
abnormal currents.
In addition the arc voltage generated at
the time of interruption has a low value
so that faults will not influence related
electric machinery and equipment.
These fuses can carry out the
protection of many types of circuits
rating from the semiconductor
overcurrents to destructive short-
circuiting faults-i.e. when the
SD-36 SM-388 SI-431 SI-429
BLC CR2L CS5F CS10F
semiconductors short or circuits fail the
sound elements will be quickly isolated
from the fault circuits.
■Features
•The total clearing I2t is small and the
semiconductor circuit is completely
protected.
•Since the peak arc voltage at the
time of interruption is low damage to
other equipment does not occur.
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Rated Rated Peak Max. Watt Fuse-link
current
voltage
arc interrupting I2t loss
voltage
(Amp
2
×sec.)
× 103Type
(A) (V) (W)
10 250V Max. 0.04 1.2 CR2LS-10
20 AC 500 0.17 3.0 CR2LS-20
30 0.35 4.0 CR2LS-30
50 0.85 6.0 CR2LS-50
75 2.3 9.0 CR2LS-75
100 4.0 12.0 CR2LS-100
20 600V Max. 0.14 4.0 CR6L-20
30 AC 1200 0.35 7.0 CR6L-30
50 1.8 9.0 CR6L-50
75 3.0 12.5 CR6L-75
100 7.0 15 CR6L-100
150 18 22.0 CR6L-150
200 30 34.0 CR6L-200
250 70 37.0 CR6L-250
300 95 40.0 CR6L-300
350 150 45.0 CR6L-350
400 200 55 CR6L-400
500 390 60 CR6L-500
600 700 70 CR6L-600
Interrupting capacity
CR2LS . 100kA at 250V AC
CR6L .... 100kA at 600V AC
•High interrupting capacity of 200kA
at 1000V AC
•The CS type is provided with a blown
fuse indicator. An alarm contact
block (1NO or 1NC) can also be
attached.
■UL recognized: CR2L/UL,CR2LS/UL,
CR6L/UL
(File No. E92312)
CSA certificated: CR2LS/UL
(File No. LO4000-4090)
TÜV: CR2LS/UL (10-100A),
CR2L/UL (150-350A)
(Rep. No. E9450643E02)
CR6L/UL (50-300A)
(Rep. No. E9560543E02)
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08/36
Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
■Specifications (UL-recognized, CSA certified, TÜV)
Rated Rated Inter- Max. Watt Fuse-link
current voltage rupting interrupting I
2
t loss
capacity (Amp
2
×sec.)
× 10
3
Type
(A) (kA) (W)
10 250V AC 10 at AC 0.04 1.2 CR2LS-10/UL
20 400V DC (pf: 0.8) 0.17 3.0 CR2LS-20/UL
30 10 at DC 0.35 4.0 CR2LS-30/UL
50 (L/R: 2ms) 0.85 6.0 CR2LS-50/UL
75 2.3 9.0 CR2LS-75/UL
100 4.0 12.0
CR2LS-100/UL
150 9.5 18.0 CR2L-150/UL
200 17 23.0 CR2L-200/UL
260 27 30.0 CR2L-260/UL
350 60 37.0 CR2L-350/UL
400 103 39.0 CR2L-400/UL
450 140 46.0 CR2L-450/UL
500 160 48.0 CR2L-500/UL
550 200 51.0 CR2L-550/UL
600 215 56.0 CR2L-600/UL
20 600V AC 100 at AC 0.14 4.0 CR6L-20/UL
680V DC (pf: 0.8)
30 10 at DC 0.35 7.0 CR6L-30/UL
(L/R: 2ms)
50 1.8 9.0 CR6L-50/UL
75 3.0 12.5 CR6L-75/UL
100 7.0 15.0 CR6L-100/UL
150 100 at AC 18 22.0 CR6L-150/UL
(pf: 0.8)
200 50 at DC 30 34.0 CR6L-200/UL
(L/R: 2ms)
300 95 40.0 CR6L-300/UL
■Specifications
Rated Inter- Max. Watt Fuse-link
current rupting interrupting I2t loss
capacity
(Amp
2
×sec.)
× 103Type
(A) (kA) (W)
4700 150 at 14000 310 CS1F-4700
125V AC
2000 150 at 1950 124 CS2F-2000
3000 250V AC 5500 216 CS2F-3000
40 200 at 1 6.4 CS5F-40
75 500V AC 3.5 12 CS5F-75
100 5 17 CS5F-100
150 10 25 CS5F-150
200 18.5 34 CS5F-200
250 33 42 CS5F-250
300 64 45 CS5F-300
350 85 56 CS5F-350
400 122 57 CS5F-400
450 131 62 CS5F-450
500 159 73 CS5F-500
600 257 80 CS5F-600
800 600 114 CS5F-800
1000 1200 110 CS5F-1000
1000 843 167 CS5F-1000-P
1200 1800 114 CS5F-1200
1200 1311 200 CS5F-1200-P
1500 3600 209 CS5F-1500
1000 200 at 1800 125 CS8F-1000
1200 800V AC 2500 176 CS8F-1200
1500 4400 220 CS8F-1500
80 200 at 10 17 CS10F-80
100 1000V AC 16 21 CS10F-100
150 37 27 CS10F-150
200 63 37 CS10F-200
250 110 44 CS10F-250
300 148 53 CS10F-300
350 211 70 CS10F-350
400 307 74 CS10F-400
500 420 90 CS10F-500
560 410 102 CS10F-560
630 450 135 CS10F-630
750 640 156 CS10F-750
800 1259 211 CS10F-800-P
1000 1722 245 CS10F-1000-P
1250 2250 330 CS10F-1250-P
1500 3200 334 CS10F-1500-C
450 100 at 350 134 CS15F-450
630 1500V AC 760 170 CS15F-630
900 1400 280 CS15F-900-P
1250 3050 350 CS15F-1250-P
Note: •Peak arc voltage
CS1F ..... Max. 450V
CS2F ..... Max. 750V
CS5F ..... Max. 1000V
CS8F ..... Max. 2000V
CS10F ... Max. 2000V
CS15F ... Less than 3000V
•An alarm contact block AHX2905 (1NO) or AHX2915 (1NC) can be
attached to CS type. (Sold separately)
See page 08/44.
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Note: •Peak arc voltage
CR2LS, CR2L .... Max. 500V
CR6L .................. Max. 1200V
•The peak arc voltage is obtained by interruption caused by the listed
interrupting current at rated voltage.
•This indcates the values when the conductors specified in UL
Standards are connected and rated current apply.
•TÜV: CR2LS, 2L: Up to 350A
CR6L: 50 to 300A
Note: UL recognized fuse
In the UL recognized fuses, a fuse with a blown inidcation fuse, or a
fuse both with a blown indication fuse and a precision switch is also
UL recognized.
Examples: CR2L-200G/UL
CR2LS-30S/UL
CR6L-100G/UL
■CR type fuse with optional accessory
Fuse with blown indication fuse
CR2L (S)- G
AF88-446
Fuse with blown indication fuse and precision switch
CR2L (S)- S Precision switch (SPDT)
CRX-1
AF88-445 AF88-442
precision switch
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Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
08/37
08
■Dimensions, mm
●BLC
BLC012, 020, 023 BLC045 BLC075 to 140
Type Rated A B øDød Color of Mass
current indicator (g)
(A)
BLC012-1 12 50 10 13 10 Grey 12
BLC020-1 20 50 10 13 14 Yellow 12
BLC023-1 23 50 10 13 14 Violet 12
BLC045-1 45 50 10 27 20 White 62
BLC075-1 75 63 6 34 5 Silver 120
BLC090-1 90 63 6 34 8 Red 120
BLC120-1 120 63 6 47 8 Yellow 120
BLC140-1 140 63 6 47 8 Light red 215
Note: The BLC type fuse link requires a holder in use. The size of the
holder differs according to the fuse ratings. Select the most suitable
one after referring to the Table on
page 08/44
.
For drawings see
page 08/32
.
●CR2L-450 or smaller, CR2LS
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Dimensions for reference only. Confirm before construction begins.
Type A B C D E a×b F G H Mass
CR2L-30 80 58 18 21.5 37 9×11 90 1.5 26.5 42g
CR2L-50
CR2L-75 80 58 20 30.5 44 9×11 90 3 32.5 100g
CR2L-100
CR2L-125
CR2L-140
CR2L-150
CR2L-175
CR2L-200 85 60 25 33.5 47 11×13 93 3.2 33.5 130g
CR2L-225
CR2L-260
CR2L-300
CR2L-325
CR2L-350 95 70 30 42 54 11×13 98 4 39 220g
CR2L-400
CR2L-450
CR2LS-10 56 42 12 18.5 34.5 6.5×8.5 78 2 25 28g
CR2LS-20
CR2LS-30
CR2LS-50
CR2LS-75
CR2LS-100
Note: The dimensions of the fuses with suffix. UL are the same as those of the
standard ones.
■Ordering information
Specify the following:
1. Type number
■Type number nomenclature
BLC 012-1
Rated current: 12 to 140A
Plug-in type super rapid fuse
CS 10F-1000
-P/ UL
UL recognized (CR2L, CR2LS, CR6L)
CSA certificated (CR2LS)
TÜV (CR2LS, CR2L, CR6L)
2-fuse connected parallel
Optional accessory
(See page 08/44)
G: With blown indication fuse
S: With blown indication fuse
and precision switch
Rated current
10 to 4700A
Rated voltage
2L, 2LS: 250V AC, 6L: 600V AC
1F: 150V AC, 2F: 250V AC
5F: 500V AC, 8F: 800V AC
10F: 1000V AC, 15F: 1500V AC
CR: Barrel-shaped super rapid fuse
CS: Cubic-shaped super rapid fuse
Mass: 450g
●CR2L-500 to -600
øD
B
ød
A
ød
B
A
øD
øD
A
ød
B
Blown indicatin
fuae (G type)
Mounting hole a × b
B
H
E
D
C
F
A
G
ø37
46.5
Blown indication
fuse (G type)
70
31
41.5
43
46
28
54
84
30
98
84
95
8
Mounting hole 11×13
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08/38
Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
■Dimensions, mm
●CR6L-20, CR6L-30, CR6L-50 ●CR6L-75 to 300 ●CR6L-350 to 600
Type A B C D E F G H a×b Mass (g)
CR6L-75 95 70 25 34 47 102 3.2 33.5 11×13 150
CR6L-100
CR6L-150
CR6L-200 107 82 30 42 54 107 4 39 11×13 246
CR6L-250
CR6L-300
Type A B C D Mass (g)
CR6L-350 107 82 43 107 493
CR6L-400 121 96 43 114 522
CR6L-500
CR6L-600 121 96 47.4 114 545
●CS1F-4700
CS2F-2000, 3000
●CS5F-40 to 1500
CS10F-80 to 750
CS15F-450, 630
●CS8F-1000, 1200, 1500
Voltage Type A B C D M Mass
(Max.) (g)
500V CS5F-40 47 47 42.5 65.5 M8 320
CS5F-75
CS5F-100
CS5F-150
CS5F-200
CS5F-250 57 51 47 70 M8 510
CS5F-300
CS5F-350
CS5F-400 72 51 54.5 77 M10 800
CS5F-450
CS5F-500
CS5F-600
CS5F-800
CS5F-1000 72 51 54.5 77 M12 830
CS5F-1200
CS5F-1500
Voltage Type A B C D M Mass
(Max.) (g)
800V CS8F-1000 72 74 54.5 84 M12 1060
CS8F-1200
CS8F-1500 72 82 54.5 84 M8 1150
1000V CS10F-80 47 71 42.5 65.5 M8 420
CS10F-100
CS10F-150 57 74 47 70 M8 690
CS10F-200
CS10F-250
CS10F-300 72 74 54.5 77 M10 1060
CS10F-350
CS10F-400
CS10F-500
CS10F-630
CS10F-750
1500V CS15F-450 72 105 54.7 77 M10 1400
CS15F-630
Mass: 42g
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
34.5
18
Blown indication
fuse (G type)
Mountng hole 6.5×8.5
23.5
18.5
ø17.5
25
62
47
27
12
88
74
76
2
E
Blown indication
fuse (G type)
Mountng hole a × b
H
D
B
C
G
F
A
84
28
41.5
43
46
46.5
30
B
ø37
54
Mountng hole 11×13
8
D
C
A
Blown indication
fuse (G type)
Blown fuse
indicator
Alarm contact block AHX2905(NO)
AHX2915(NC)
2-MIO
72 51
72
30
54.5 7
84 max.
M
AB
Alarm contat block
Blown fuse indicator
N.P.
A
C
D7
7
A
7C
30
A
M
Blown fuse indicator
Alarm contact block
D
B
Mass: 800g
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08/39
08
■Dimensions, mm
●CS5F-P CS10F-P, CS15F-P
Voltage Type H L Mass (g)
500V CS5F-1000-P 51 69 1900
CS5F-1200-P
1000V CS10F-800-P 74 92 2420
CS10F-1000-P
CS10F-1250-P
1500V CS15F-900-P 105 123 3100
CS15F-1250-P
●CS10F-1500-C
Current-limiting characteristic
Mass: 2500g
■Characteristic curves
BLC
Melting time-current characteristic
Operating time-current characteristic
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
M10
N.P.
86
158
5
754.5
H
L
7max.77
ø1572
40
72
Alarm contat block
108
107
89.5
M10 M10
max.77
7
7
74
99
5
M10
Alarm
contat
block
ø15 72
72
40
Time
Minute
Second
Current (A)
Time
Second Minute
Current (A)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
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08/40
Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
■Characteristic curves
CR2L, CR2LS
Melting time-current characteristic
Operating time-current characteristic
Current-limiting characteristic
CR6L
Melting time-current characteristic
Operating time-current characteristic
Current-limiting characteristic
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Minute
Time
Current (A)
Minute
Time
Current (A)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
Time
Minute
Second
Current (A)
Time
Minute
Second
Current (A)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
Second Second
CR6L-20
CR6L-30
CR6L-50
CR6L-75
CR6L-100
CR6L-150
CR6L-200
CR6L-250
CR6L-300
CR6L-600
CR6L-350
CR6L-400
CR6L-500
CR6L-20
CR6L-20
CR6L-20
CR6L-30
CR6L-50
CR6L-75
CR6L-100
CR6L-150
CR6L-200
CR6L-250
CR6L-300
CR6L-600
CR6L-350
CR6L-400
CR6L-500
CR6L-20
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Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
08/41
08
■Characteristic curves
CS1F
Melting time-current characteristic CS2F
Melting time-current characteristic
Operating time-current characteristic Operating time-current characteristic
Current-limiting characteristic Current-limiting characteristic
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Minute
Second
Time
Current ( × 103A)
Second Minute
Time
Current ( × 103A)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
Current ( × 103A)
Time
Minute
Second
Time
Minute
Second
Current ( × 103A)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
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08/42
Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
■Characteristic curves
CS5F
Melting time-current characteristic CS8F
Melting time-current characteristic
Operating time-current characteristic Operating time-current characteristic
Current-limiting characteristic Current-limiting characteristic
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Minute
Time
Current ( × 103A)
Minute
Time
Current ( × 103A)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
Time
Minute
Second
Current ( × 10A)
Time
Minute
Second
Current ( × 10A)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
Second Second
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Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
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08/43
08
■Characteristic curves
CS10F
Melting time-current characteristic CS15F
Melting time-current characteristic
Operating time-current characteristic Operating time-current characteristic
Current-limiting characteristic Current-limiting characteristic
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Minute
Time
Second
Current ( × 10A)
Current ( × 10A)
Minute
Second
Time
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
Max. Let-through current (Peak value) kA
Available current (Sym, rms) I eff. (kA)
Minute
Second
Time
Current ( × 103A)
Current ( × 103A)
Minute
Second
Time
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08/44
Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
■Operating indication
●Blown fuse indication
FUJI Super Rapid Fuses are available
in BLC, CR and CS types. These types
have different methods of indicating a
blown fuse.
●BLC type
A blown fuse is indicated by the color
tip on the ferrule of the fuse being
ejected as shown in Fig. 1. This can be
seen through the window of the fuse
holder.
●CR type
This fuse does not have a blown
indicator but if a trigger fuse is
connected as shown in Fig. 2 this will
provide the alarm for blown fuse.
●CS type
This fuse is provided with a blown fuse
indicator. In this case a pin in the
contact pad is ejected after the fuse
has been blown. If electrical
connections for lamps or alarms are
required fit the contact block (1NO or
1NC) to the pad as shown in Fig. 3.
Fig. 1 Fig. 3
Fig. 2
BLC type
CR type
Alarm contact block
AHX2905, 2915
CS 10F with alarm
contact block
■Alarm contact block ratings
Type Contact Rated
voltage (V)
AHX2905 1NO 24
110
220
AHX2915 1NC 440
550
Inductive load
Rated operational Rated
current (A) capacity (W)
6 150
1.3 140
0.45 100
0.2 85
0.15 85
DC
Resistive load
Rated operational Rated
current (A) capacity (W)
6 150
2.5 275
1 220
0.4 175
0.3 165
AC
Inductive cos
ϕ
=0.3~1
Rated operational Rated
current (A) capacity (VA)
6 150
6 660
6 1320
2.5 1100
2 1100
■Fuse holder for BLC type fuse
FUJI BLC fuses require special
holders. Select the most suitable one
which corresponds to the rated current
of the fuse.
Dimensions:
See page 08/32
.
Fuse link Fuse holder
BLC Surface connection
Fuse link Rated Base Screw cap Adaptor
current Surface Rear ring
connection connection
Type (A) Type Type Type Type
BLC012-1 12 AFa30 Ba30 Pa30 R20
BLC020-1 20 AFa30 Ba30 Pa30 –
BLC023-1 23 AFa30 Ba30 Pa30 –
BLC045-1 45 AFa60 Ba60 Pa60 –
BLC075-1 75 AFa100 Ba100 Pa100 R75
BLC090-1 90 AFa100 Ba100 Pa100 –
BLC120-1 120 AFa200 Ba200 Pa200 –
BLC140-1 140 AFa200 Ba200 Pa200 –
AF88-446
SH-384
SM-385 CS10F
SD-36
SD-36 AF88-439
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
Line
Load
Alarm
circuit
Alarm
circuit
Trigger
fuse
R
F
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08/45
08
■Application and selection guide
BLC, CR and CS-type – Super rapid
fuse
When selecting fuses for
semiconductor rectifier circuit protection
the following conditions must be
satisfied.
For additional details contact FUJI.
■Conditions of application
1. The rated interrupting current of the
fuse must be greater than the
estimated short circuit current of the
circuit.
Available short Rated interrupting
circuit current current of fuse
of rectifier circuit
2. The let-thru current value of fuse
must be less than the allowable 1/2
cycle surge current value.
Semiconductor – 1/2
Fuse let-thru cycle allowable surge
current value current 10ms (at 50Hz)
3. The total clearing I2t value which the
fuse requires to complete interruption
must be less than the
allowable
I2t
value of semiconductor.
Fuse – total Semiconductor – I2t
clearing I2t
4. The rated current of the fuse must be
greater than the average forward
current of the semiconductor.
Fuse –Semiconductor –
rated current average forward current
5. The rated current and voltage of the
fuse must be greater than those of
the rectifier circuit.
Fuse – rated Rectifier circuit –
current and current and voltage
voltage
Method of application
Semiconductor rectifier equipment has
a variety of rectifier circuits. Taking the
3-phase bridge rectifier circuit as an
example – Fig. (a) and (b) as shown in
the following.
Although the number of fuses used in
the line fuse method (a) is half the
number used in the element fuse
method (b), the fuses must have a
larger current capacity.
Fig. (a)
Line fuse method
In this method the fuses are connected to
the AC line side.
Fig. (b)
Element fuse method
In this method the fuses are connected in
series to the semiconductor element.
■Fuse ratings
When selecting fuses various factors
such as protection, coordination and
load, etc. must be considered.
However, in this catalog the main
matters such as voltage, current and I2t
only are explained.
●Rated voltage
The rated voltage of the fuse indicates
the maximum operational voltage and
this also indicates the root-mean-
square value of the AC sinusoidal wave
voltage. Select fuses having a rated
voltage exceeding the voltage obtained
by the formula shown in the following
table. (Fig. 1)
Do not select current-limiting fuses with
rated voltages drastically exceeding the
rectifier circuit voltage. It is necessary
to consider the arc voltage.
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Fig. 1 Rated voltage required by fuses
Wire connection Wiring diagram Rated voltage of Fuse (VFN rms)
type For line fuse For element fuse
Single-phase bridge VFN a · EaVFN a · Ea
3-phase bridge VFN a · EaVFN a · Ea
3-phase, double star VFN a · 3 · EaVFN a · 3 · Ea
Remarks: The 'a' is a coefficient where the regulation of the AC input voltage is taken into account. This
is a=1.1 in case of voltage regulation ±10%.
Fig. 2 Element current and line current
Wire connection Wiring diagram Element fuse method Line fuse method
type Element current IaLine current
Single-phase bridge
3-phase bridge
3-phase, double star
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Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
E
a
E
a
E
a
I
a
I
a
I
a
I
d
I
d
I
d
I
I
I
I
Ia = I = d
= 0.707d
Id
√_
2
_
Ia =
= 0.577dI
Id
√_
3
_I= Id
= 0.816dI
2
3
I = Ia =
= 0.289dI
Id
2√_
3
_
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08/46
Fuji Electric FA components & Systems Co., Ltd./D & C Catalog
Information subject to change without notice
●Rated current
The current values in fuses in the line
fuse system and the element fuse
system are different. Obtain the
correct current value from the table on
page 08/48
(Fig. 2).
When selecting the rated current of a
fuse choose a fuse having an
amperage rating greater than the
current which flows in the semi-
conductor if the load is continuous and
a fixed current.
If the current which flows in the
semiconductor is greater than the rated
current of the fuse connect the fuses in
parallel. However, in this case, if the
numbers of fuses arranged in parallel
are 'n', then the I2t value of the fuse will
be n2·I2t and n2 times the I2t value of
one fuse. This should be taken into
consideration when protective
coordination is taken into account.
In the case of the circuit where the load
rapidly varies the fuse element will
suffer from mechanical deterioration
and be damaged by thermal stress.
In loads of this type the deterioration
characteristics of the fuse must be
closely considered.
Moreover if the fuse current – time
characteristics of the fuse selected is
less than the overload characteristics
of the semiconductor element then
complete protection can be obtained.
However, if the semiconductor element
has a large capacity then protective
cooperation is very difficult to arrange.
The fuses are used to isolate the
shorted semiconductor element circuit
from sound operating circuits.
■Total clearing I2t
The total clearing I2t of fuse is a very
important factor when considering the
protective coordination of the
semiconductor. This total clearing I2t is
the value where the arcing I2t is added
to the melting I2t. Therefore it is
necessary to satisfy the following
formula.
Fuse – total Semiconductor
clearing I2tI
2t
The total clearing I2t of fuse depends
upon the operational voltage and
interrupting current.
Therefore, for this reason if a 500 Volts
fuse is used in a 300 Volts circuit the
total clearing I2t is reduced by 50–70%.
However, the reduction rate varies
according to the type of fuse
construction. This must be checked
and confirmed once more.
Example
I2t
All I2t values are ampere2 seconds.
The I2t data for silicon diodes or
thyristor elements are normally given in
their respective catalogs. If the A2S
data is not given in their catalog obtain
the value in the following manner. If
protection is needed for a 250V, 150A
(Io) diode having a maximum allowable
peak half sine wave current of 2700A, it
is important that the fuse has a total I2t
value lower than that of the diode.
Calculation
Maximum I2t diode = ( )2 0.0167
= ( )2 0.0167
= 30,400A2 Sec.
From the table (
Page 08/38
), the fuse
with a total I2t nearest to 30,400A2 Sec.
is the 260 Ampere fuse (CR 2L-260).
■Interrupting current
The rated interrupting current of the
fuse must exceed the maximum value
(Symmetrical RMS value) of the
estimated circuit fault current.
■Peak arc voltage
In the case of the current-limiting fuse
an arc voltage (overvoltage) is
generated at the time of interruption
due to its fusible element construction.
It is necessary to check that this peak
arc voltage does not exceed the
semiconductor's maximum (Non-
repetitive peak) reverse voltage value.
■Current limitation
Select a fuse whose let-thru current
value does not exceed the allowable
1/2 cycle surge current of the
semiconductor. The allowable surge
current is the peak value of the current
which in case at 50Hz is allowed to
flow for 10ms. In the current-limiting
fuse the fault must be cleared in the
shortest possible time or in the first
1/2 cycle.
Available current is the current which
would flow if the fuse were not current-
limiting.
This would cause damage to
equipment. Let-thru current is the
actual current allowed to flow by the
current limiting action of the fuse. A
number of let-thru current graphs are
given in this catalog and example is
given in the following paragraph. The
method of reading this graph is
provided for your reference.
How to find a let-thru current
– Example
Fuse: 200 Amps 500V
Available R.M.S symmetrical current:
100,000 Amps
Let-thru peak current (Instantaneous):
11,600 Amps
Let-thru R.M.S. current
11,600 ÷ 1.7 = 6,800 Amps
This example clearly shows that while
a 100kA (rms, sym) current is
available, the fuse limits the current let-
thru to 6,800 Amperes (rms, sym).
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1 Peak
2
2700
2
Low Voltage Fuses
BLC, CR and CS types
Super Rapid Fuses
M:Melting time
A :Arcing time
T :Total clearing time
105,000
100,000A
Available RMS symmetrical current(Ampere)
Let-thru
Available
Let-thru peak current(Amperes)-Peak
11,600 200A
Peak let-thru current
(Actual short-circuit current)
Time
Current
M
T
A
Peak current of first half cycle
of available peak current
(AC component)
Short circuit current that
would pass without current-
limiting fuse.
DC component
Available instantaneous peak current Pf=1
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