保險絲有何作用？

保險絲（Fuse）的作用係保護電氣產品不會受外界電壓不穩定或過高時，起一個保護作用，當超過它容許通過的電流時就會燒斷，另一方面相反的，如電氣本身出了問題，引至電流流動過大，亦起了一個安全的作用，把電源斷開以免造成火災。
保險絲有好多種，最多使用的係熱斷式，用於一般大多數的家電、影視、音響。還有就是可恢復式，如家中的電箱掣箱內的，故障排除後把保險絲的開關復位就可再用，之後還有快溶式、慢溶式用於特殊場合。
常見的保險絲，電流小的有幾十 mA的，用於小型電子產品，大的有幾百 Amp。用於樓宇或重型機電，數值大小通常都會標於當眼的地方。

type of current (Basic):
1. AC current (under 220/380 rated voltage)
2. DC current (in HK -No DC power transmission system)
3. Harmonic Current -AC mode
4. ...........design, measure, calculation, ......

Current : I; unit: Ampere (A)

type of fuse; (not included the circuit breaker)
1. BS3036 Rewireable fuse, (Less fault current capacity, subject to size of element)
2. BS88 Part 2 HRC/HBC fuse, (High fault current capacity)
3. Twins fuse (like pair of BS88) protect the power electronic equipment.
e.g. variable speed drive (at least 200kW rated)
4. BS1362 general 13A plug fuse

Function of fuse:
1.equipment overload protection
2.short circuit protection
mean- due under design fault current, isolated the power source, reduce the equipment or fire burn risk.

Type of fuse's element:
1. copper
2. platnium
3. alumimium (less)
4. others

Insulation of element:
1. air
2. minerals

Rating of fuse(AC);
1. BS3036, less in market, 5A, 15A, 30A
2. BS 88 part-2, 2A, 5A, 6A, 10A,15A, 20A, 30A, 45A, 60A, 80A, 100a, 125A, .
......up to 800A (all kinds, please refer to IEE regulation such as BS7671)
3. BS 1362, 2A, 5A, 10A, 13A, (20A not specific BS standard)

note: DC fuse, less product in the market (common to use in circuit breaker)