High speed fuses
6
British BS 88
Introduction
General information
British BS 88 contents
Fuse
Amp
volts
range
240
6-900
690
6-710
Page
6-95
6-98
Accessories
Indicator system and fuse bases
6-102
Designed and tested to:
• BS 88: Part 4
• IEC 269: Part 4
• UL Recognized
Eaton offers the industry’s widest range of British style
semiconductor fuses and accessories.
Eaton’s Bussmann series British style products use
innovative arc quenching techniques and high grade
materials to provide:
• Minimal energy let-through (I2t)
• Excellent DC performance
• Good surge withstand profile
British BS 88 fuse ranges
Amps
6-900
6-710
Vac
240
690
Vdc
150
500
British style fuses are typically found in equipment
manufactured in the United Kingdom or British
Commonwealth countries. However, North American
manufacturers have begun to specify British style fuses —
particularly in UPS applications at 240V or less — to take
advantage of their size, performance and cost benefits.
Voltage rating
All Bussmann series British style fuses are tested to IEC 269:
Part 4. This standard requires a test voltage which is 5%
higher than the rated voltage. In North America, fuses are
required to clear only their rated voltage.
Accessories
Trip-indicator fuses are available for use in parallel with the
main fuse. Indicator fuses can be attached to the associated
fuselink, or mounted separately in panel-mounted fuseclips.
In addition, a push-on adapter and microswitch attachment
are available, to provide remote indication. Fuse blocks are
also available for most applications.
6-94
BUSSMANN SERIES FULL LINE CATALOG
1007—July 2015
Eaton.com/bussmannseries
High speed fuses
6
British BS 88
LCT, LET, LMT, LMMT – 240V: 6-900A
Arc voltage
Specifications
Description: BS 88 style
stud-mount fuses.
Dimensions: See dimensions
illustrations.
Ratings:
Volts: — 240Vac/150Vdc
Amps: — 6-900A
IR: — 200kA RMS Sym.
Agency information: CE, Designed and tested to: BS 88
Part 4, IEC 269 Part 4, UL Recognized. All fuses above have
been tested at 318Vac. Consult Eaton for specific UL
Recognition status.
Electrical characteristics
Total clearing I2t
The total clearing I2t at rated
voltage and at power factor
of 15% are given in the
electrical characteristics. For
other voltages, the clearing
I2t is found by multiplying by
correction factor, K, given as
a function of applied working
voltage, Eg, (rms).
1.0
0.8
0.6
1)
0.4
0.2
50
Catalog numbers
2)
100
150
Eg
200
250
1) LCT
2) LET, LMT, LMMT
7.1
26.2 41.8 56
9.7
17.7
19.1
Fig. 3: LMT
1mm = 0.0394” / 1” = 25.4mm
Fig. 4: LMMT
25.4
25.4
31
13.5
59
31 59 84
84
13.5
10.3
10.3
41
83
38.1
Indicator (Optional)
2)
250
100
Power losses
Watts loss at rated current
is given in the electrical
characteristics. The curve
allows the calculation of
the power losses at load
currents lower than the
rated current. The
correction factor, Kp, is
given as a function of the
RMS load current, Ib, in %
of the rated current.
1)
500
1.0
Kp
0.8
200
1) LCT
2) LET, LMT, LMMT
300
Eg
0.6
0.5
0.4
0.3
0.2
0.1
30 40 50
60
70
Ib
80 90 100%
Electrical characteristics
12.7
8.4
UL
38
Catalog
numbers
6LCT
10LCT
12LCT
16LCT
20LCT
25LET
32LET
35LET
50LET
63LET
80LET
100LET
125LET
160LET
180LETa
160LMT
200LMT
250LMT
315LMT
355LMT
400LMT
450LMT
400LMMT
500LMMT
630LMMT
710LMMT
800LMMT
900LMMT
Type
LCT
LET
LMT
LMMT
Rated
current
RMS-amps
6
10
12
16
20
25
32
35
50
63
80
100
125
160
180
160
200
250
315
355
400
450
400
500
630
710
800
900
Pre-arc
2
3.8
7
20
25
18
32
50
100
180
300
600
600
1100
1600
1100
1500
3200
6000
8000
14000
18000
6000
14000
24000
32000
52000
75000
I2t (A2 sec)
Clearing
at 120V
6
12
22
50
80
120
200
320
500
1100
1900
3800
3800
7000
12000
7000
10000
20000
35000
50000
70000
100000
35000
80000
150000
200000
300000
400000
Clearing
at 240V
9
22
32
100
160
250
450
600
1400
2200
3800
7500
7500
16000
29000
16000
20000
40000
75000
100000
160000
220000
80000
170000
300000
460000
600000
800000
Watts
loss
1.0
2.5
2.5
2.5
4.0
4.0
5.0
5.0
7.0
9.0
10.0
10.0
16.0
20.0
21.0
17.0
28.0
28.0
35.0
35.0
40.0
42.0
60.0
64.0
75.0
77.0
82.0
97.0
• Watts loss provided at rated current.
• Note: 7LET, 10LET, 12LET and 16LET are available for replacement purposes on existing
equipment.
• See accessories on page 6-102.
Features and benefits
• Excellent cycling capability
• Excellent DC performance
• Low arc voltage and low
energy let-through (I2t)
•
•
•
•
Typical applications
DC common bus
AC and DC drives
Power converters/rectifiers
Reduced voltage starters
Data Sheet: 720004
BUSSMANN SERIES FULL LINE CATALOG
1007—July 2015
Eaton.com/bussmannseries
6-95
High speed
fuses
8.7
1.2
K
4
28 38 47
6.4
1.4
Fig. 2: LET
Dimensions - mm
Fig. 1: LCT
5.5
1.6
This curve gives the peak
arc voltage, UL, which
may appear across the
fuse during its operation
as a function of theapplied
working voltage, Eg, (rms)
at a power factor of 15%.
750
High speed fuses
6
British BS 88
LCT 6-20A: 240V
LET 25-180A: 240V
Time-current curve
Time-current curve
104
6
4
104
6
4
2
2
103
103
6
4
6
4
2
6
4
2
102
2
101
6
4
2
100
6
4
2
101
6
4
25LET
32LET
35LET
50LET
63LET
2
100
6
4
2
10–1
10–1
6
4
6
4
2
2
10–2
10–2
6
4
6
4
2
2
10–3
10–3
6
4
6
4
2
2
10–4
80LET
100LET
125LET
160LET
180LETa
6
4
Virtual Pre-Arcing Time In Seconds
Virtual Pre-Arcing Time In Seconds
2
6LCT
10LCT
12LCT
16LCT
20LCT
102
2
4
6
8
2
4
6 8
101
102
Prospective Current In Amps RMS
2
4
6
8
10–4
103
Data Sheet: 35785296
2
101
4
6
8 102
Data Sheet: 35785293
Peak let-through curve
2
105
900LMMT
800LMMT
710LMMT
630LMMT
450LMT
400 & 500LMMT
355LMT
315LMT
250LMT
6
4
2
104
180LET
200LMT
160LET & LMT
125 & 100LET
80LET
6
Peak Let-Through Current
4
2
103
6
4
63LET
50LET
35LET
32LET
25LET
2
10
2
20LCT
16LCT
12LCT
10LCT
6LCT
6
4
2
101
6-96
101
2
SYMMETRICAL FAULT
FULLY ASYMMETRICAL FAULT
4
6
102
BUSSMANN SERIES FULL LINE CATALOG
2
4
6
103
2
4
6
104
Prospective Short-Circuit Current Symmetrical RMS
1007—July 2015
2
2
4
Prospective Current In Amps RMS
4
6
105
Eaton.com/bussmannseries
6
8 103
High speed fuses
6
British BS 88
LMT 160-450A: 240V
LMMT 400-900A: 240V
Time-current curve
Time-current curve
104
104
6
4
6
4
2
2
103
103
6
4
6
4
2
101
6
4
6
4
2
100
6
4
2
10–1
6
4
2
101
6
4
2
100
6
4
2
10–1
6
4
2
2
10–2
6
4
10–2
6
4
2
2
10–3
10–3
6
4
6
4
2
2
102
2
4
6
8 103
2
4
6
Prospective Current In Amps RMS
8 104
10–4
Data Sheet: 35785294
2
102
4
6
8 103
2
4
Prospective Current In Amps RMS
6
8 104
Data Sheet: 35785295
High speed
fuses
Peak let-through curve
2
105
900LMMT
800LMMT
710LMMT
630LMMT
450LMT
400 & 500LMMT
355LMT
315LMT
250LMT
6
4
2
10
Peak Let-Through Current
10–4
400LMMT
500LMMT
630LMMT
710LMMT
800LMMT
900LMMT
102
Virtual Pre-Arcing Time In Seconds
2
Virtual Pre-Arcing Time In Seconds
2
160LMT
200LMT
250LMT
315LMT
355LMT
400LMT
450LMT
102
6
4
4
180LET
200LMT
160LET & LMT
125 & 100LET
80LET
6
4
2
103
6
4
63LET
50LET
35LET
32LET
25LET
2
102
20LCT
16LCT
12LCT
10LCT
6LCT
6
4
2
101
10
1
2
SYMMETRICAL FAULT
FULLY ASYMMETRICAL FAULT
4
6
102
2
4
6
103
2
4
6
104
Prospective Short-Circuit Current Symmetrical RMS
BUSSMANN SERIES FULL LINE CATALOG
2
4
6
105
1007—July 2015
Eaton.com/bussmannseries
6-97
High speed fuses
6
British BS 88
CT, ET, FE, EET, FEE, FM, FMM, MT, MMT –
690V: 6-710A
Arc voltage
This curve gives the
peak arc voltage, UL,
which may appear
across the fuse during its
operation as a function
of the applied working
voltage, Eg, (rms) at a
power factor of 15%.
Specifications
Description: BS 88 style
stud-mount fuses.
Dimensions: See dimensions
illustrations.
Ratings:
Volts: — 690Vac/500Vdc
Amps: — 6-710A
IR: — 200kA RMS Sym.
Agency information: CE, Designed and tested to: BS 88
Part 4, IEC 269 Part 4, UL Recognized. MT and MMT —
350Vdc (IEC) rating. Consult Eaton for UL Recognition
status.
Electrical
characteristics
1.6
Total clearing I2t
1.4
The total clearing I2t at rated
voltage and at power factor
of 15% are given in the
electrical characteristics. For
other voltages, the clearing
I2t is found by multiplying by
correction factor, K, given as
a function of applied working
voltage, Eg, (rms).
Dimensions - mm
Fig. 1: CT
5.5
4
8.7
•
•
•
•
0.8
0.6
0.2
1)
2)
Eg
200
300
400
500
600 690
•
•
•
•
1) CT, ET, EET, FE, FEE, MT, MMT
2) FM, FMM
7.1
12.7
17.1
Watts loss at rated
current is given in the
electrical characteristics.
The curve allows the
calculation of the power
losses at load currents
lower than the rated
current. The correction
factor, Kp, is given as a
function of the RMS load
current, Ib, in % of the
rated current.
1) CT
2) ET, FE, EET, FEE, FM, FMM
0.6
0.5
0.4
0.3
0.2
0.1
30 40 50
60
Ib
80 90 100%
70
Fig. 5: FMM, MMT
25.4
50
25.4
A
50
113
A
14
31.8
37
10.3
10.3
19
41
38.1
Data Sheet: 720024
BUSSMANN SERIES FULL LINE CATALOG
1.0
Kp
0.8
Eg
600 660
400
13.5
1mm = 0.0394” / 1” = 25.4mm
6-98
200
Fig. 4: FM, MT
46 70 94
19.1
500
Typical applications
DC common bus
DC drives
Power converters/rectifiers
Reduced voltage starters
8.7
11.9
2)
Features and benefits
Excellent cycling capability
Excellent DC performance
Low arc voltage and low energy let-through (I2t)
Low watts loss
Fig. 3: EET, FEE
48 63.5 77
9.7
8.7
1.0
Fig. 2: ET, FE
54.8 64.3 74.6
6.4
K
1)
1000
Power losses
1.2
0.4
UL
1500
1007—July 2015
Eaton.com/bussmannseries
38
Figs. 4 & 5 “A” Dimensions
Type
“A”
FM
80-85mm
FMM
80-85mm
MT
85mm
MMT
85mm
83
113
High speed fuses
6
British BS 88
Catalog numbers
ET
FE
EET
FEE
FM
FMM
MT
MMT
• Watts loss provided at rated current.
• Note: FC, 8ET, 12ET, 15ET, 20ET, 65EET and 75EET are available for replacement
purposes on existing equipment.
• See accessories on page 6-102.
Time-current curve
104
6
4
2
103
6
4
25ET
32ET
35ET
40ET
45ET
56ET
63ET
80ET
2
102
6
4
Virtual Pre-Arcing Time In Seconds
CT
Watts
loss
2
3
3
7
7
7
11
11
9
11
14
16
18
9
9
11
11
12
17
20
20
23
19
27
35
39
24
32
36
46
46
52
40
40
44
48
48
55
55
85
90
100
100
100
120
26
26
27
32
35
42
51
42
42
42
47
51
54
60
57
64
64
86
105
2
101
6
4
6CT
10CT
12CT
16CT
20CT
2
100
6
4
2
10–1
6
4
2
10–2
6
4
2
10–3
6
4
2
10–4
2
4
6
8 101
2
4
6
2
8 102
4
6
Prospective Current In Amps RMS
8 103
Peak let-through curve
6
4
2
315MT 355MT
280MT
250MT
105
6
180MT
160MT
4
2
710MMT
630MMT
560MMT
500MMT
450MMT
400MMT
355MMT
315MMT
280MMT
200MT
225MMT
200MMT
180MMT
104
Peak Let-Through Current
Type
CT 6-20, ET 25-80A: 690V
High speed
fuses
Catalog
numbers
6CT
10CT
12CT
16CT
20CT
25ET
32ET
35ET
40ET
45ET
56ET
63ET
80ET
35FE
40FE
45FE
50FE
63FE
71FE
80FE
90FE
100FE
90EET
110EET
140EET
160EET
100FEE
120FEE
140FEE
160FEE
180FEE
200FEE
180FM
200FM
225FM
250FM
280FM
315FM
350FM
400FMM
450FMM
500FMM
550FMM
630FMM
700FMM
160MT
180MT
200MT
250MT
280MT
315MT
355MT
180MMT
200MMT
225MMT
280MMT
315MMT
355MMT
400MMT
450MMT
500MMT
560MMT
630MMT
710MMT
Electrical characteristics
Rated
I2t (A2 sec)
current
Clearing Clearing
RMS-amps Pre-arc
at 415V
at 660V
6
1.8
8.5
12
10
7
30
48
12
10
40
65
16
16
66
110
20
32
150
220
25
25
150
250
32
32
190
350
35
52
310
500
103
600
900
40
45
103
680
1100
56
135
950
1500
63
171
1200
2000
80
360
2500
4000
35
33
130
200
40
52
180
300
45
76
270
450
50
103
380
600
63
135
480
750
71
210
600
950
80
250
900
1500
90
360
1300
2100
100
470
1800
2800
90
490
3000
4500
600
4000
6500
110
140
1050
7000
12000
160
1500
10000
17000
100
400
1600
2400
120
540
1900
3100
140
850
2500
3800
160
1000
3700
5700
180
1400
5300
8400
200
1900
7100
11400
180
1400
7500
13500
200
2600
10500
18500
225
3700
14500
26500
250
5200
20500
37500
280
7000
30500
55000
315
10000
40000
77000
350
15000
60000
105000
400
10000
40000
72500
450
15000
60000
105000
500
20000
82000
150000
550
30000
120000
215000
630
45000
180000
310000
700
60000
245000
420000
160
2400
15000
25000
180
3800
25000
38000
200
6000
40000
58000
250
11500
80000
110000
280
16500
100000
150000
315
19000
125000
180000
355
22000
160000
200000
180
1650
12000
18000
200
2200
16000
23000
225
3700
26000
40000
280
6600
47000
70000
315
8600
62000
91000
355
13500
97000
140000
400
21000
150000
220000
450
30000
220000
320000
500
42000
300000
450000
560
60000
430000
640000
630
68500
500000
720000
710
78000
600000
850000
6
4
2
103
6
4
2
20CT
16CT
12CT
10CT
6CT
102
6
4
160EET
140EET
110EET
90EET
80ET
63ET
56ET
45ET
40ET
35ET
32ET
25ET
2
101
101
2
4
6
102
2
4
6
103
2
4
6
104
Prospective Short-Circuit Current Symmetrical RMS
2
4
6
105
2
Data Sheet: 35785312
BUSSMANN SERIES FULL LINE CATALOG
1007—July 2015
Eaton.com/bussmannseries
6-99
High speed fuses
6
British BS 88
EET 90-160A, MT 160-355A: 690V
MMT 180-710A: 690V
Time-current curve
104
Time-current curve
104
6
4
2
2
103
6
4
2
101
6
4
90EET
110EET
140EET
160EET
2
100
6
4
2
10
–1
6
4
180MMT
200MMT
225MMT
280MMT
315MMT
355MMT
6
4
2
100
6
4
2
10–1
10–2
6
4
6
4
6
4
2
10–3
2
10–4
6
4
2
6
4
2
10–3
6
4
2
101
2
10–2
400MMT
450MMT
500MMT
560MMT
630MMT
710MMT
2
102
Virtual Pre-Arcing Time In Seconds
Virtual Pre-Arcing Time In Seconds
103
160MT
180MT
200MT
250MT
280MT
315MT
355MT
6
4
2
102
6
4
2
4
6
8 102
2
4
6
8 103
2
4
6
Prospective Current In Amps RMS
8 104
6
4
2
10–4
2
102
4
6 8
2
4
103
Prospective Current In Amps RMS
Data Sheet: 35785313
Data Sheet: 35785311
Peak let-through curve
6
4
2
315MT 355MT
280MT
250MT
105
6
180MT
160MT
4
2
710MMT
630MMT
560MMT
500MMT
450MMT
400MMT
355MMT
315MMT
280MMT
200MT
225MMT
200MMT
180MMT
Peak Let-Through Current
104
6
4
2
103
6
4
2
20CT
16CT
12CT
10CT
6CT
102
6
4
160EET
140EET
110EET
90EET
80ET
63ET
56ET
45ET
40ET
35ET
32ET
25ET
2
101
6-100
101
2
4
BUSSMANN SERIES FULL LINE CATALOG
6
102
2
4
6
103
2
4
6
104
Prospective Short-Circuit Current Symmetrical RMS
1007—July 2015
2
4
6
105
2
Eaton.com/bussmannseries
6
8
104
High speed fuses
6
British BS 88
FE 35-100A and FM 180-350A: 690V
FEE 100-200A and FMM 400-700A: 690V
Time-current curve
103
Time-current curve
104
6
4
6
4
2
2
6
4
103
6
4
2
Virtual Pre-Arcing Time In Seconds
2
180FM
200FM
220FM
250FM
280FM
315FM
350FM
102
6
4
2
101
6
4
2
35FE
40FE
45FE
50FE
63FE
71FE
80FE
90FE
100FE
100
6
4
2
10–1
6
4
2
10–2
6
4
2
101
6 100FEE
4 120FEE
140FEE
2 160FEE
180FEE
100 200FEE
6
4
2
10–1
6
4
2
10–2
6
4
2
10–3
6
4
2
2
10–4
400FMM
450FMM
500FMM
550FMM
630FMM
700FMM
102
6
4
Virtual Pre-Arcing Time In Seconds
104
2
4
6
8 102
2
4
6
8 103
2
4
6
Prospective Current In Amps RMS
8 104
10–3
6
4
2
10–4
Peak let-through curve
2
102
4
350FM
315FM
280FM
250FM
225FM
200FM
180FM
4
2
103
6
4
2
100FE
90FE
80FE
71FE
63FE
50FE
45FE
40FE
35FE
102
6
4
2
2
4
6
102
2
4
6
103
2
4
6
104
Prospective Short-Circuit Current Symmetrical RMS
700FMM
4
450FMM
630FMM
550FMM
500FMM
400FMM
2
104
8
6
4
2
103
200FEE
8
4
6
105
180FEE
6
2
160FEE
140FEE
4
2
Data Sheet: 35785314
104
2
Peak Let-Through Current
Peak Let-Through Current
6
101
8
6
104
8
High speed
fuses
6
2
6
Peak let-through curve
105
101
4
6 8
2
4
103
Prospective Current In Amps RMS
120FEE
100FEE
102
2
4
6
103
2
4
6
104
2
4
Prospective Short-Circuit Current Symmetrical RMS
6
105
2
Data Sheet: 35785292
BUSSMANN SERIES FULL LINE CATALOG
1007—July 2015
Eaton.com/bussmannseries
6-101
High speed fuses
6
British BS 88 fuse accessories
Indicator system
CL1 panel mount clips
CL1 panel mount fuse clips
are available for mounting a
trip-indicator when mounting
directly on the fuse is
impractical. Order part
number CL1.
Trip-indicators
Trip-indicators are available for use in parallel with the
main fuse. They can either be attached to the associated
fuse or mounted separately in panel mounted fuse clips,
reference CL1. A push-on adapter and microswitch
attachment is available for use with the trip indicator to
give the facility of remote indication, reference MAI.
Fuse ratings of 20A and below cannot usually
accommodate a trip-indicator.
When a trip-indicator is to be attached to the main fuse an
accessory pack comprising a pair of mounting clips and an
appropriate trip indicator would be required. The clips are
snapped onto the fuse end caps and the indicator is
pressed into clips as shown.
Trip-indicator
Dimensions - mm
TI500
500
700
130
0.3
1.5A
100,000
23
46
TI700
700
1000
350
0.45
1.5A
100,000
23
46
Fuse Indicator Kits
Kit. ref.
EC-250
MC250
EC-600
MC600
MC700
Details
Fuse mount
Indicator kits
(Includes one
indicator
and two clips)
B
21
C
6
D
Ref.
TI250
TI500
TI600
TI700
TI1100
TI1500
TI2000
TI2500
Dim. “A” (mm)
37.6
47.5
55.7
61.8
98.4
120.6
147.5
198.3
CL1 panel mount clip
Dimensions - mm
For use
with fuse ref.
LET
LMT and LMMT
FE, FEE and ET
FM and FMM
MT and MMT
Microswitch adapter – MAI
We offer a microswitch, complete with adapter for
securing the indicator. The microswitch is provided with
double pole, single throw contacts, having both a normally
open and a normally closed position. A special material has
been employed in the construction of the adapter to
provide reliable operation in the range of temperatures
associated with standard operating conditions and during
fuse operation.
50.8
B
NO
NC
NC
NO
Dimensions - in mm
Microswitch and adapter Type MAI
Current rating:
AC 50/60Hz resistive load @ 250V RMS
AC 50/60Hz resistive load @ 127V RMS
DC, resistive load @ 110Vdc
DC, resistive load @ 30Vdc
Maximum working voltage:
Contact-to-contact (RMS)
Contact-to-contact (RMS)
Maximum DC volts:
6-102
6.0
Terminal arrangement
4A
6A
0.7A DC
2A DC
1000V
1500V
110Vdc
BUSSMANN SERIES FULL LINE CATALOG
1007—July 2015
Eaton.com/bussmannseries
6.35
6.8
RMS volts
250
500
600
700
1100
1500
2000
2500
14
RMS
volts
250
250
660
660
700
F
E
0.8
A
Electrical specifications
Type
Maximum RMS voltage
Maximum peak voltage
Maximum DC voltage
Cold resistance (ohms)
Maximum permissible steady-state current
Interrupting capacity (RMS Symm.)
Pre-Arcing I2t
Total I2t (max volts)
Trip
indicator
8.7