High Speed Fuses
British BS 88 — 240V: 6-900A
LCT, LET, LMT, LMMT
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 Cooper Bussmann for
specific UL Recognition status.
Electrical Characteristics
1.6
Total Clearing I2t
K
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).
1.2
1.0
0.8
0.4
2)
Eg
50
100
150
200
250
Fig. 2: LET
7.1
4
5.5
26.2 41.8 56
28 38 47
9.7
12.7
6.4
17.7
8.4
19.1
8.7
Fig. 4: LMMT
Fig. 3: LMT
1mm = 0.0394” / 1” = 25.4mm
25.4
25.4
31 59
31
59
84
13.5
13.5
10.3
10.3
41
83
38.1
Indicator (Optional)
1)
500
2)
250
Eg
100
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.
300
1.0
Kp
0.8
0.6
0.5
0.4
0.3
0.2
Ib
0.1
30 40 50
38
84
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
60
70
80 90 100%
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 195.
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
188
200
1) LCT
2) LET, LMT, LMMT
Electrical Characteristics
1)
0.2
UL
Power Losses
Catalog Numbers
0.6
1) LCT
2) LET, LMT, LMMT
Dimensions (mm)
Fig. 1: LCT
750
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%.
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa
High Speed Fuses
British BS 88 — 240V: 6-900A
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
6LCT
10LCT
12LCT
16LCT
20LCT
102
6
4
2
102
2
Virtual Pre-Arcing Time In Seconds
2
101
6
4
2
100
6
4
2
10–1
101
6
4
25LET
32LET
35LET
50LET
63LET
2
100
6
4
High Speed
Fuses
2
10–1
6
4
6
4
2
2
10–2
10–2
6
4
6
4
2
2
10–3
6
4
10–3
6
4
2
2
10–4
2
4
6
8
2
4
6 8
101
102
Prospective Current In Amps RMS
2
4
6
8
10–4
103
2
101
4
6
8 102
2
4
6
8 103
Prospective Current In Amps RMS
Data Sheet: 35785296
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
Virtual Pre-Arcing Time In Seconds
80LET
100LET
125LET
160LET
180LETa
6
4
4
2
103
6
4
63LET
50LET
35LET
32LET
25LET
2
10
2
20LCT
16LCT
12LCT
10LCT
6LCT
6
4
2
SYMMETRICAL FAULT
FULLY ASYMMETRICAL FAULT
101
101
2
4
6
102
2
4
6
103
2
4
6
104
2
4
6
105
Prospective Short-Circuit Current Symmetrical RMS
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa
189
High Speed Fuses
British BS 88 — 240V: 6-900A
LMT 160-450A: 240V
LMMT 400-900A: 240V
Time-Current Curve
Time-Current Curve
104
6
4
104
6
4
2
2
103
103
6
4
6
4
2
101
6
4
400LMMT
500LMMT
630LMMT
710LMMT
800LMMT
900LMMT
102
6
4
Virtual Pre-Arcing Time In Seconds
2
Virtual Pre-Arcing Time In Seconds
2
160LMT
200LMT
250LMT
315LMT
355LMT
400LMT
450LMT
102
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
10–4
102
2
4
6
8 103
2
4
6
10–4
8 104
2
102
Prospective Current In Amps RMS
4
6
8 103
2
Data Sheet: 35785294
Data Sheet: 35785295
Peak Let-Through Curve
2
105
900LMMT
800LMMT
710LMMT
630LMMT
450LMT
400 & 500LMMT
355LMT
315LMT
250LMT
6
4
2
10
4
180LET
200LMT
160LET & LMT
125 & 100LET
80LET
Peak Let-Through Current
6
4
2
103
6
4
63LET
50LET
35LET
32LET
25LET
2
102
20LCT
16LCT
12LCT
10LCT
6LCT
6
4
2
SYMMETRICAL FAULT
FULLY ASYMMETRICAL FAULT
101
10
1
2
4
6
102
2
4
6
103
2
4
6
104
2
4
6
105
Prospective Short-Circuit Current Symmetrical RMS
190
4
Prospective Current In Amps RMS
For product data sheets, visit www.cooperbussmann.com/datasheets/ulcsa
6
8 104