For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa 187
High Speed
Fuses
British BS 88 Fuses
General Information
Designed and tested to:
• BS 88: Part 4
• IEC 269: Part 4
• UL Recognized
Cooper Bussmann offers the industry’s widest range of
British style semiconductor fuses and accessories.
Cooper Bussmann 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 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 Cooper Bussmann 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.
Introduction
British BS 88 Contents
Fuse Amp
Volts Range Page
240 6-900 188-190
690 6-710 191-194
Accessories
Indicator System & Fuse Bases 195
British BS 88 Fuse Ranges
AAmmppssVVaaccVVddcc
6-900 240 150
6-710 690 500
High Speed Fuses
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%.
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 correc-
tion factor, Kp, is given as
a function of the RMS load
current, Ib, in % of the
rated current.
Catalog Numbers
EElleeccttrriiccaall CChhaarraacctteerriissttiiccssRRaatteeddII22tt ((AA22SSeecc))
CCaattaallooggCCuurrrreennttCClleeaarriinnggCClleeaarriinnggWWaattttss
NNuummbbeerrssTTyyppeeRRMMSS--AAmmppssPPrree--aarrccaatt 112200VVaatt 224400VVLLoossss
6LCT 6 2 6 9 1.0
10LCT 10 3.8 12 22 2.5
12LCT LCT 12 7 22 32 2.5
16LCT 16 20 50 100 2.5
20LCT 20 25 80 160 4.0
25LET 25 18 120 250 4.0
32LET 32 32 200 450 5.0
35LET 35 50 320 600 5.0
50LET 50 100 500 1400 7.0
63LET LET 63 180 1100 2200 9.0
80LET 80 300 1900 3800 10.0
100LET 100 600 3800 7500 10.0
125LET 125 600 3800 7500 16.0
160LET 160 1100 7000 16000 20.0
180LETa 180 1600 12000 29000 21.0
160LMT 160 1100 7000 16000 17.0
200LMT 200 1500 10000 20000 28.0
250LMT 250 3200 20000 40000 28.0
315LMT LMT 315 6000 35000 75000 35.0
355LMT 355 8000 50000 100000 35.0
400LMT 400 14000 70000 160000 40.0
450LMT 450 18000 100000 220000 42.0
400LMMT 400 6000 35000 80000 60.0
500LMMT 500 14000 80000 170000 64.0
630LMMT LMMT 630 24000 150000 300000 75.0
710LMMT 710 32000 200000 460000 77.0
800LMMT 800 52000 300000 600000 82.0
900LMMT 900 75000 400000 800000 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 195.
Features and Benefits
• Excellent cycling capability
• Excellent DC performance
• Low arc voltage and low
energy let-through (I2t)
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa
188
High Speed Fuses
British BS 88 — 240V: 6-900A
5641.8
26.2
17.7
19.1
12.7
7.1
9.7
Fig. 2: LET
473828
6.4
8.4
8.7
4
5.5
Dimensions (mm)
Fig. 1: LCT
1mm = 0.0394” / 1” = 25.4mm
LCT, LET, LMT, LMMT
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 Cooper Bussmann 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).
845931
83
38
25.4
13.5
10.3
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
10050 150 200 250
1)
2) Eg
K
845931
41
38.1
25.4
10.3
13.5
Fig. 3: LMT
Fig. 4: LMMT
Indicator (Optional)
1) LCT
2) LET, LMT, LMMT
Kp
1.0
0.8
0.4
0.5
0.6
0.3
0.2
0.1
30 40 50 60 70 80 90 100%
Ib
750
500
250
100 200 300
1)
2)
Eg
UL
1) LCT
2) LET, LMT, LMMT
Typical Applications
• DC common bus
• AC and DC drives
• Power converters/rectifiers
• Reduced voltage starters
Data Sheet: 720004
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa 189
British BS 88 — 240V: 6-900A
Peak Let-Through Curve
LET 25-180A: 240V
Time-Current Cur ve
LCT 6-20A: 240V
Time-Current Cur ve
104
103
102
10–1
10–2
10–3
10–4
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
2468
10122468 2
1022468
103
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
20LCT
16LCT
12LCT
10LCT
6LCT
104
103
102
10122468 2
1022468
103
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
63LET
50LET
35LET
32LET
25LET
180LETa
160LET
125LET
100LET
80LET
10–4
10–3
10–2
10–1
Prospective Short-Circuit Current Symmetrical RMS
101102
264246
103246
104246
105
Peak Let-Through Current
101
6
2
4
2
102
4
6
2
103
6
4
104
6
4
2
2
105
SYMMETRICAL FAULT
FULLY ASYMMETRICAL FAULT
20LCT
16LCT
12LCT
10LCT
6LCT
25LET
32LET
35LET
50LET
63LET
80LET
125 & 100LET
160LET & LMT
200LMT
180LET
250LMT
315LMT
355LMT
400 & 500LMMT
450LMT
630LMMT
710LMMT
800LMMT
900LMMT
High Speed
Fuses
High Speed Fuses
Data Sheet: 35785296 Data Sheet: 35785293
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa
190
High Speed Fuses
British BS 88 — 240V: 6-900A
10–4
10–3
10–1
102
10222468 2
1032468
104
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
104
315LMT
450LMT
400LMT
355LMT
250LMT
200LMT
160LMT
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
103
10–2
10–1
10–3
10–2
102
103
104
10222468 2
1032468
104
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
10–4
710LMMT
900LMMT
800LMMT
630LMMT
500LMMT
400LMMT
Prospective Short-Circuit Current Symmetrical RMS
101102
264246
103246
104246
105
Peak Let-Through Current
101
6
2
4
2
102
4
6
2
103
6
4
104
6
4
2
2
105
SYMMETRICAL FAULT
FULLY ASYMMETRICAL FAULT
20LCT
16LCT
12LCT
10LCT
6LCT
25LET
32LET
35LET
50LET
63LET
80LET
125 & 100LET
160LET & LMT
200LMT
180LET
250LMT
315LMT
355LMT
400 & 500LMMT
450LMT
630LMMT
710LMMT
800LMMT
900LMMT
Peak Let-Through Curve
LMMT 400-900A: 240V
Time-Current Cur ve
LMT 160-450A: 240V
Time-Current Cur ve
Data Sheet: 35785294 Data Sheet: 35785295
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa 191
British BS 88 — 690V: 6-710A
High Speed
Fuses
High Speed Fuses
CT, ET, FE, EET, FEE, FM, FMM, MT, MMT
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 Cooper Bussmann for 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).
Dimensions (mm)
Fig. 1: CT
7763.5
48
17.1
19.1
12.7
7.1
9.7
113
A50
41
38.1
25.4
10.3
13.5
113A50
83
38
25.4
10.3
14
Fig. 2: ET, FE
74.664.354.8
6.4
8.7
8.7
4
5.5
Fig. 3: EET, FEE Fig. 4: FM, MT Fig. 5: FMM, MMT
1mm = 0.0394” / 1” = 25.4mm Figs. 4 & 5 “A” Dimensions
Type “A”
FM 80-85mm
FMM 80-85mm
MT 85mm
MMT 85mm
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%.
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.
Features and Benefits
• Excellent cycling capability
• Excellent DC performance
• Low arc voltage and low energy let-through (I2t)
• Low watts loss
Typical Applications
• DC common bus
• DC drives
• Power converters/rectifiers
• Reduced voltage starters
1500
1000
500
200 400 600 660
Eg
UL
1)
2)
1) CT
2) ET, FE, EET, FEE, FM, FMM
200 300 400 500 600 690
0.2
0.4
0.6
0.8
1.0
1.2
1.4
1.6
1) 2)
Eg
K
1) CT, ET, EET, FE, FEE, MT, MMT
2) FM, FMM
Kp
1.0
0.8
0.4
0.5
0.6
0.3
0.2
0.1
30 40 50 60 70 80 90 100%
Ib
Data Sheet: 720024
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa
192
High Speed Fuses
British BS 88 — 690V: 6-710A
103
10–1
2468
10122468 2
1022468
103
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
10CT
12CT
16CT
20CT
6CT
32ET
25ET
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
56ET
80ET
63ET
45ET
40ET
35ET
10–4
10–3
10–2
102
104
Prospective Short-Circuit Current Symmetrical RMS
Peak Let-Through Current
2
4
2
6
6
4
2
4
6
4
2
6
4
2
6
246246246246
101
102
103
104
105
1011021031041052
20CT
16CT
12CT
10CT
6CT
80ET
63ET
56ET
45ET
40ET
35ET
32ET
25ET
710MMT
630MMT
560MMT
500MMT
450MMT
315MT 355MT 400MMT
280MT 355MMT
250MT 315MMT
280MMT
200MT
180MT 225MMT
160MT 200MMT
180MMT
160EET
140EET
110EET
90EET
Peak Let-Through Curve
CT 6-20, ET 25-80A: 690V
Time-Current Cur ve
EElleeccttrriiccaall CChhaarraacctteerriissttiiccss
RRaatteeddII22tt ((AA22SSeecc))
CCaattaallooggCCuurrrreennttCClleeaarriinnggCClleeaarriinnggWWaattttss
NNuummbbeerrssTTyyppeeRRMMSS--AAmmppssPPrree--aarrccaatt 441155VVaatt 666600VVLLoossss
6CT 6 1.8 8.5 12 2
10CT 10 7 30 48 3
12CT CT 12 10 40 65 3
16CT 16 16 66 110 7
20CT 20 32 150 220 7
25ET 25 25 150 250 7
32ET 32 32 190 350 11
35ET 35 52 310 500 11
40ET ET 40 103 600 900 9
45ET 45 103 680 1100 11
56ET 56 135 950 1500 14
63ET 63 171 1200 2000 16
80ET 80 360 2500 4000 18
35FE 35 33 130 200 9
40FE 40 52 180 300 9
45FE 45 76 270 450 11
50FE 50 103 380 600 11
63FE FE 63 135 480 750 12
71FE 71 210 600 950 17
80FE 80 250 900 1500 20
90FE 90 360 1300 2100 20
100FE 100 470 1800 2800 23
90EET 90 490 3000 4500 19
110EET EET 110 600 4000 6500 27
140EET 140 1050 7000 12000 35
160EET 160 1500 10000 17000 39
100FEE 100 400 1600 2400 24
120FEE 120 540 1900 3100 32
140FEE FEE 140 850 2500 3800 36
160FEE 160 1000 3700 5700 46
180FEE 180 1400 5300 8400 46
200FEE 200 1900 7100 11400 52
180FM 180 1400 7500 13500 40
200FM 200 2600 10500 18500 40
225FM 225 3700 14500 26500 44
250FM FM 250 5200 20500 37500 48
280FM 280 7000 30500 55000 48
315FM 315 10000 40000 77000 55
350FM 350 15000 60000 105000 55
400FMM 400 10000 40000 72500 85
450FMM 450 15000 60000 105000 90
500FMM FMM 500 20000 82000 150000 100
550FMM 550 30000 120000 215000 100
630FMM 630 45000 180000 310000 100
700FMM 700 60000 245000 420000 120
160MT 160 2400 15000 25000 26
180MT 180 3800 25000 38000 26
200MT 200 6000 40000 58000 27
250MT MT 250 11500 80000 110000 32
280MT 280 16500 100000 150000 35
315MT 315 19000 125000 180000 42
355MT 355 22000 160000 200000 51
180MMT 180 1650 12000 18000 42
200MMT 200 2200 16000 23000 42
225MMT 225 3700 26000 40000 42
280MMT 280 6600 47000 70000 47
315MMT 315 8600 62000 91000 51
355MMT MMT 355 13500 97000 140000 54
400MMT 400 21000 150000 220000 60
450MMT 450 30000 220000 320000 57
500MMT 500 42000 300000 450000 64
560MMT 560 60000 430000 640000 64
630MMT 630 68500 500000 720000 86
710MMT 710 78000 600000 850000 105
• 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 195.
Data Sheet: 35785312
Catalog Numbers
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa 193
British BS 88 — 690V: 6-710A
High Speed
Fuses
High Speed Fuses
103
104
102
10–1
10–2
2468
10222468 2
1032468
104
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
160EET
140EET
110EET
90EET
200MT
355MT
315MT
280MT
250MT
180MT
160MT
10–4
10–3
Prospective Short-Circuit Current Symmetrical RMS
Peak Let-Through Current
2
4
2
6
6
4
2
4
6
4
2
6
4
2
6
246246246246
101
102
103
104
105
1011021031041052
20CT
16CT
12CT
10CT
6CT
80ET
63ET
56ET
45ET
40ET
35ET
32ET
25ET
710MMT
630MMT
560MMT
500MMT
450MMT
315MT 355MT 400MMT
280MT 355MMT
250MT 315MMT
280MMT
200MT
180MT 225MMT
160MT 200MMT
180MMT
160EET
140EET
110EET
90EET
Peak Let-Through Curve
EET 90-160A, MT 160-355A: 690V
Time-Current Cur ve
104
103
102
10–1
10–3
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
10222468 2
1032468
104
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
280MMT
355MMT
315MMT
225MMT
200MMT
180MMT
630MMT
710MMT
560MMT
500MMT
450MMT
400MMT
10–4
10–2
MMT 180-710A: 690V
Time-Current Cur ve
Data Sheet: 35785313
Data Sheet: 35785311
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa
194
High Speed Fuses
British BS 88 — 690V: 6-710A
104
103
102
10–1
10–2
10–3
10–4
10222468 2
1032468
104
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
120FEE
140FEE
160FEE
180FEE
200FEE
100FEE
550FMM
700FMM
630FMM
500FMM
450FMM
400FMM
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
FEE 100-200A & FMM 400-700A: 690V
Time-Current Cur ve
Prospective Short-Circuit Current Symmetrical RMS
Peak Let-Through Current
102246
2
4
6
103
8
2
8
4
6
104
2
4
6
8
103246
104246
1052
180FEE
100FEE
120FEE
140FEE
160FEE
200FEE
400FMM
450FMM
500FMM
550FMM
630FMM
700FMM
Peak Let-Through Curve
103
102
10–1
10–2
10–4
2468
10222468 2
1032468
104
2
4
6
2
6
4
100
2
6
4
101
2
6
4
2
6
4
2
6
4
6
4
2
6
2
4
100FE
35FE
40FE
45FE
50FE
63FE
71FE
80FE
90FE
350FM
315FM
280FM
250FM
220FM
200FM
180FM
Prospective Current In Amps RMS
Virtual Pre-Arcing Time In Seconds
10–3
104
FE 35-100A & FM 180-350A: 690V
Time-Current Cur ve
Prospective Short-Circuit Current Symmetrical RMS
Peak Let-Through Current
2
4
2
6
6
4
2
6
4
2
6
4
246 246 246 246
101
102
103
104
105
1011021031041052
350FM
315FM
280FM
250FM
225FM
200FM
180FM
100FE
90FE
80FE
71FE
63FE
50FE
45FE
40FE
35FE
Peak Let-Through Curve
Data Sheet: 35785314 Data Sheet: 35785292
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa 195
British BS 88 Fuse Accessories
High Speed
Fuses
High Speed Fuses
IInnddiiccaattoorr SSyysstteemm
TTrriipp--IInnddiiccaattoorrss
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.
EElleeccttrriiccaall SSppeecciiffiiccaattiioonnss
Type TI500 TI700
Maximum RMS Voltage 500 700
Maximum Peak Voltage 700 1000
Maximum DC Voltage 130 350
Cold Resistance (ohms) 0.3 0.45
Maximum permissible steady-state current 1.5A 1.5A
Interrupting Capacity (RMS Symm.) 100,000 100,000
Pre-Arcing I2t2323
MMiiccrroosswwiittcchh AAddaapptteerr –– MMAAII
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.
MMiiccrroosswwiittcchh aanndd AAddaapptteerr TTyyppee MMAAII
Current Rating:
AC 50/60Hz resistive load @ 250V RMS 4A
AC 50/60Hz resistive load @ 127V RMS 6A
DC, resistive load @ 110Vdc 0.7A DC
DC, resistive load @ 30Vdc 2A DC
Maximum Working Voltage:
Contact-to-contact (RMS) 1000V
Contact-to-contact (RMS) 1500V
Maximum DC Volts: 110V DC
Ref. Dim. “A” (mm) RMS Volts
TI250 37.6 250
TI500 47.5 500
TI600 55.7 600
TI700 61.8 700
TI1100 98.4 1100
TI1500 120.6 1500
TI2000 147.5 2000
TI2500 198.3 2500
RMS For use
Kit. Ref. Details Volts with Fuse Ref.
EC-250 Fuse Mount 250 LET
MC250 Indicator Kits 250 LMT & LMMT
EC-600 (Includes one 660 FE, FEE & ET
MC600 indicator 660 FM & FMM
MC700 and two clips) 700 MT & MMT
E
C
A
B
D
F
621 0.8
6.8
6.35
NO
NC
NC
NO
TTeerrmmiinnaall AArrrraannggeemmeenntt
TTrriipp--IInnddiiccaattoorr
DDiimmeennssiioonnss -- mmmm
DDiimmeennssiioonnss iinn mmmm
FFuussee IInnddiiccaattoorr KKiittss
6.0 8.7
50.8
B
14
CCLL11 PPaanneell MMoouunntt CClliippss
CL1 Panel mount fuse clips
are available for mounting a
trip-indicator when mounting
directly on the fuse is
impractical. Order part
number CL1.
CCLL11 PPaanneell MMoouunntt CClliipp
DDiimmeennssiioonnss -- mmmm
Trip
Indicator