The rated voltage of a fuse-link must be greater than or equal to the operating
voltage of the equipment which is to be protected.
The difference between an applied AC voltage or is DC voltage to a fuse; The fuse-links are on principle suitable for use at alternating and direct voltage. The breaking capacity at direct-voltage is however considerably lower
than the one at alternating voltage. The performance of the fuse-link at direct-voltage mainly depends on the size of the time-constant = L/R of the load circuit.
Glass body fuses seem to have a DC voltage rating half that of a maximum AC voltage rating [in general]. While Ceramic cases appear to have the same maximum voltage rating regardless of the operating voltage, AC or DC.
The Military standard for Fuses; MIL-PRF-23419 does not seem to differentiate between AC or DC voltages for low voltage fuses.
-- From Military sources
Voltage rating. The voltage rating is the maximum dc or ac root mean square (rms) voltage for which a fuse is designed......
Fuse selection: The following steps should apply in the selection of a fuse for any application:
Step 1: Select a fuse with a voltage rating equal to or in excess of the circuit voltage.
-- From Ferraz Shawmut
Voltage Rating: The maximum voltage at which a fuse is designed to operate. Exceeding the voltage rating of a fuse impairs its ability to clear an overload or short circuit safely. Fuse can be used at any voltage below the fuse voltage rating; a 250V fuse can be used in 125V circuits. Voltage ratings are assumed to be for AC unless specifically labeled as DC.
-- From Cooperbussmann
Voltage Ratings
The voltage rating of the fuse must be greater than or equal to the circuit
voltage. Because the fuse has such low resistance, the voltage rating
becomes critical only when the fuse is trying to open. The fuse must be
able to open quickly, extinguish the arc after the fuse element has melted
and prevent the system open-circuit voltage from restriking across the
open fuse element.
Fuses are specified to interrupt within a maximum of 5 seconds when
driven at 200% of their rated current for nominal ratings up to and
including 10 amperes. A fuse with a nominal rating of 15 amperes is
specified to interrupt within a maximum of 10 seconds when driven at 200%
of its rated current. The power supply shall be capable of delivering
appropriate levels of current to achieve short fusing times. There is an
additional derating of 0.2%/°C for an increase in the temperature of
fuse body.
A manufacturers listing for Fuses, also, How to derate a Fuse
Derating guidelines for other components; Guideline for Derating Electronic Components
Engineering Key Words: Fuse, Component Derating, reliability, Sizing, Derate, Ampacity, Fusing, Insulation, Rated Temp, Temperature, Guide, Guideline, Example, Surge, Class, Design, Derate Fuse Operation.
