MIL-PRF-15160K
5. PACKAGING
5.1 Packaging. For acquisition purposes, the packaging requirements shall be as specified in the contract or order
(see 6.2). When packaging of materiel is to be performed by DoD or in-house contractor personnel, these personnel
need to contact the responsible packaging activity to ascertain packaging requirements. Packaging requirements are
maintained by the Inventory Control Point's packaging activities within the Military Service or Defense Agency, or
within the Military service's system commands. Packaging data retrieval is available from the managing Military
Department's or Defense Agency's automated packaging files, CD-ROM products, or by contacting the responsible
packaging activity.
6. NOTES
(This section contains information of a general or explanatory nature that may be helpful, but is not mandatory.)
6.1 Intended use. Fuses covered by this specification are intended for the protection of electrical and electronic
equipment. The fuses are unique due to the fact that these devices must be able to operate satisfactorily under the
following demanding conditions: Vibration, 100 g's of shock, and 500 percent rated current tests. In addition, these
requirements are verified under a qualification system.
6.1.1 Characteristic A fuses. Normal opening characteristic A fuses are intended for general circuit protection
when only nominal short circuit currents are available. Where higher interrupting capacity is desirable, use
characteristic C fuses.
6.1.2 Characteristic C fuses. Normal opening characteristic C fuses are intended for general circuit protection
where there is a possibility of extremely high short circuit currents. Characteristic C fuses can be substituted for
characteristic A fuses; however, the reverse is not true.
6.1.3 Characteristic B fuses. Time delay characteristic B fuses are intended for use in circuits containing motors
and other circuits where provision must be made for momentary surges. The fuses should be used only when
nominal short circuit currents are available. Consideration should be given to using characteristic BR fuses in lieu of
characteristic B fuses wherever possible. Characteristic B fuses cannot be used in rejection type fuseclips intended
for characteristic BR fuses.
6.1.4 Characteristic BR fuses. Time delay characteristic BR fuses are intended for use in circuits containing
motors and in other circuits where provision must be made for momentary surges. These fuses are capable of
interrupting extremely high short circuit currents. They have a "rejection" feature which when used with "rejection"
type fuseclips will prevent fuses such as the characteristic A, B, or C from being substituted. Characteristic BR fuses
can be substituted for characteristic B fuses in all applications even when standard fuseclips are used.
6.1.5 Fuse selection. The following steps should apply in the selection of a fuse for any application:
a. Step 1. Select a fuse with a voltage rating equal to or in excess of the circuit voltage (see 6.1.5.1).
b. Step 2. The short circuit interrupting rating of the fuse should be checked to determine that it is adequate to
protect against the short circuit currents that the particular equipment or circuit can be exposed to.
c. Step 3. The ambient temperature in which the fuse is to be used should be compared to the curves shown on
figure 1 or figure 2 to determine the effect the ambient will have on the current rating. For example, if a
characteristic A fuse is to be used in a 60°C ambient, it will only carry 95 percent of its normal rating; a fuse
which is used in a minus 20°C ambient will carry 107 percent of its nominal rating.
d. Step 4. A fuse rating should be selected on the basis of equipment ampere load with compensation made for
ambient temperature (see figure 1 and figure 2). Characteristics A and C fuses should not be loaded to more than 80
percent of the fuse rating (or 80 percent of the adjusted rating based on ambient temperature consideration) to avoid
nuisance openings caused by inrush currents and other harmless overloads. Time delay (characteristic B or BR)
fuses can be loaded to a higher level because of the ability to override harmless overloads, transients, and inrush
currents of short duration.
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