For other power factor

values, the total clearing

integral can be calculat-

ed as a multiple of the

clearing integrals, the

correction factor K and

the correction factor X.

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 cur-

rent is given in the electri-

cal characteristics. The

curve allows the calcula-

tion 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 .

Cut-Off Current

A fuse operation relating to short-circuits only. When a fuse

operates in its current-limiting range, it will clear a short-cir-

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.

A asymmetrical current

B symmetrical current

For product data sheets, visit www.cooperbussmann.com/products/datasheet.asp

88

High Speed Fuses

Prospective Current in Amperes RMS

10

2 ≈ 10

2

2

10

3

10

4

10

5

10

3

10

4

10

5

10

6

A

B

General applications

Rated Voltage

volts rms. Fuses tested to IEC are tested at 10% above their

rated voltage. British Style BS 88 fuses are tested at 5%

above its rated voltage. UL recognition tests are performed at

the rated voltage.

Rated Current

Rated current is given in amperes rms. Cooper Bussmann

fuses can continuously carry the rated current.

Melting Characteristic

The melting char-

acteristic shows

the virtual melting

time in seconds as

a function of the

prospective current

in amperes rms.

The fuses are spe-

cially constructed

for short-circuit pro-

tection against high

level fault currents.

Loading and opera-

tion of the fuse in

the non-continu-

ous/dashed section

of the melt curve

must be avoided.

The curve can also

be read as the real

melting time as a

function of the

RMS value of the

pre-arc current.

Clearing Integrals

rated voltage and at

power factor of 15% are

given in the electrical

characteristics. For

other voltages, the

multiplying by correction

factor, K, given as a

function of applied work-

ing voltage, Eg, (rms).

10

4

10

3

10

2

10

1

2

24

6

8

2

10

2

24

6

8 10

3

2

4

6

2

6

4

10

0

2

6

4

10

1

2

6

4

2

6

4

2

6

4

6

4

2

6

2

4

Prospective Current In Amperes RMS

10

–4

10

–3

10

–2

10

–1

K

1.5

1.0

0.5

0.4

0.3

0.2

100 200 300 400 500 600 660

E

g

1.0

0.9

0.8

0.7

0.1

0.2

0.3

0.4

0.5

COS

X

U

L

1.4

1.2

6

8

7

9

5

4

3

200 300

400

500

600 660

1.0

0.8

0.4

0.5

0.6

0.3

0.2

0.1

30 40 50

60

70

80 90 100%

I

b