Short Range Certificate Course

In marine radio communication equipment fuses are quite often used. A fuse is a protection against too high current. Fuses alows passage of normal currents, but are interrupting a short circuit or overload condition that could cause damage to the radio equipment.


Fuses are not all the same, we recognize "fast", "slow" and "time-delayed" fuses. A “fast” fuse will react immediately when the current is too high. A “slow” fuse will have a delayed reaction. A "time-delayed" fuse will react even slower.

On a fuse we can discover some marks, for example:

• F 5A/60V, this means that it is a “fast” fuse (F), maximum current 5A, maximum allowed voltage 60V
• S 100mA/250V, this means that it is a “slow” fuse (S), maximum current 100mA, maximum allowed voltage 250V
• T 400mA/250V, this means that it is a “time-delayed” (T) fuse, maximum current 400mA, maximum allowed voltage 250V
  

When a fuse is “blown out” we should try to find the reason what caused this problem before replacing the fuse. We should replace the fuse by a fuse of the same type and value.

If we don't have a spare fuse of the same value, we can use "lighter" one until we are able to replace it with the fuse of the same value. We should not use "heavier" one as the higher current may damage your equipment.

When the equipment needs a “fast” fuse this one should not be replaced by a “slow” one (of the same value), in this case the short period of higher current may damage your radio equipment.

Replacing a “slow” fuse by a “fast” fuse (of the same value) will lead to an immediate blow of your new placed fuse.