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What is it used in? Why?
Also, what are fuses in general used in?

2007-02-16 23:33:43 · 4 answers · asked by murphy 2 in Science & Mathematics Engineering

4 answers

Short blow fuse=Fast-blow fuses .

Fuses are often characterized as "fast-blow" or "slow-blow" | "time-delay", according to the time they take to respond to an overcurrent condition. Fast-blow fuses (sometimes marked 'F') open quickly when the rated current is reached. Ultrafast fuses (marked 'FF') are used to protect semiconductor devices that can tolerate only very short-lived overcurrents. Slow-blow fuses (household plug type are often marked 'T') can tolerate a transient overcurrent condition (such as the high starting current of an electric motor), but will open if the overcurrent condition is sustained.

A fuse also has a rated interrupting capacity, also called breaking capacity, which is the maximum current the fuse can safely interrupt. Generally this should be higher than the maximum prospective short circuit current though it may be lower if another fuse or breaker upstream can be relied upon to take out extremely high current shorts. Miniature fuses may have an interrupting rating only 10 times their rated current. Fuses for low-voltage power systems are commonly rated to interrupt 10,000 amperes, which is a minimum capacity regulated by the electrical code in some jurisdictions. Fuses for larger power systems must have higher interrupting ratings, with some low-voltage current-limiting "high rupturing capacity" (HRC) fuses rated for 300,000 amperes. Fuses for high-voltage equipment, up to 115,000 volts, are rated by the total apparent power (megavoltamperes, MVA) of the fault level on the circuit.

Overcurrent devices installed inside of enclosures are "derated" at least per the US NEC. This is a hold-over from the first mounting of electrical devices on the surface of slate slabs. The slate was the insulating material between devices mounted in air. So, rather than change the fuse rating, it became common to allow only 80% of the current value of the overcurrent device when the circuit is in operation for 3 hours or more (continuous loading).

As well as a current rating, fuses also carry a voltage rating indicating the maximum circuit voltage in which the fuse can be used. For example, glass tube fuses rated 32 volts should never be used in line-operated (mains-operated) equipment even if the fuse physically can fit the fuseholder. Fuses with ceramic cases have higher voltage ratings. Fuses carrying a 250 V rating can be safely used in a 125 V circuit, but the reverse is not true as the fuse may not be capable of safely interrupting the arc in a circuit of a higher voltage.

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2007-02-17 00:48:21 · answer #1 · answered by Anonymous · 3 0

Slow blow fuses are used in devices that draw a current level upon start-up that is close to the max amp rating of said device. A non slow blow fuse might fail at start-up under these conditions. Fuses are used as short circuit protection. Almost every thing electrical utilizes a fuse or circuit breaker. A circuit breaker is a resetable fuse. The average house has a 200amp service. Wall plugs are wired with 12guage wires, which have a max amp rating of 20amps. If your vacume cleaner shorted out it would try to draw 200amps through the 12guage wires,super heating them to the point they would melt and cause a fire. The 20amp circuit breaker would trip (blow) preventing this.

2007-02-17 00:42:05 · answer #2 · answered by bindermarkbob 1 · 0 0

speaking electrically, fuses are used for making electrical circuits open when ceases the normal conditions.
There are different classifications ...Fuses can be broadly divided into short blow and long blow fuses.
Short blow fuses are used in precision circuits.
These fuses blow up instantaneously when the designed value of current exceeds
Long blow fuses carry designed current level for a few period of time

2007-02-17 06:24:22 · answer #3 · answered by salim h 2 · 0 0

Fuses are used to prevent electrical circuits from overloading. This protects any equipment on the circuits and prevents fires caused by overheating of the cabeling. Circuits are rated for a specific amperage. If that amperage is exceeded an inline fuse will "blow", which means that it has burned out and the circuit is no longer connected at the fuse.

2007-02-17 00:02:01 · answer #4 · answered by dillhocl 2 · 0 0

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