LBS and fuse

[admin]

dear administrators and all engineers..

i'm a student..

i'm very confused about Load Break Switch and also Fuse..

can you help me please..

i need it for my study..

 

thanx before..

i hope u will..

:-)

[admin]

demiz said:

dear administrators and all engineers..

i'm a student..

i'm very confused about Load Break Switch and also Fuse..

can you help me please..

i need it for my study..

 

thanx before..

i hope u will..

:-)

They are two different things.

A load break switch is a device which can be manually switched by a person. It is there to be able to switch a power supply on to a load or to isolate the load. The significance of the words “load break” is that the switch is designed to be able to interrupt the current passing through it. i.e a 400A load break switch is designed to carry up to 400Amps continuoulsy and also to be able to break (switch off) up to a 400Amp flowing current.

This is in contrast to an isolator (or non load break switch) which is designed to carry the current but not interrupt it. With an isolator there must be another switch upstream to break the current as the isolator is designed to switch at zero amps.

A fuse is a non manually switchable device. It is a fault current  interruption device. It is designed to carry a given current continuously but to rupture when a current higher than that given current passes through it. The time that it will take for the fuse to rupture is dependent on how much above the fuse rating the current flowing is. As an example, a current twice that fuse rating may cuase the fuse to rupture in an hour or two. A current twenty times the rating will cause the fuse to rupture in a fraction of a second. HRC (High Rupture Capacity) fuses are capable of interrupting very high currents (many thousands of Amps) and thus are used for short circuit protection.

Some fuses are unstalled into holders but others may be bolted into circuits. With fuses in holders, you can isolate a circuit by fulling out the fuse. This is handy as you can see a visible break in the circuit. However you should never full out a fuse from an energised circuit. You should always switch the circuit off first. If you were to full a fuse on a DC (Direct Current) circuit which was feeding ai inductive load you could draw an arc which could be damaging to the equipment and even fatal to yourself. 

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[admin]

demiz said:

dear administrators and all engineers..

i'm a student..

i'm very confused about Load Break Switch and also Fuse..

can you help me please..

i need it for my study..

 

thanx before..

i hope u will..

:-)

---

A load break switch is a device designed to manually switch a circuit on and off. It can be used for manual control and isolation. It is designed to carry a particular current continuously and also to be able to interrupt that current. For example a 400A load break switch will carry up to 400A continuously and interrupt up to 400Amps. This is in contrast to an isolator( or non-load break) switch which is designed to isolate the circuit only. For example a 400Amp isolator will carry 400Amps continuously but the circuit has to be switched off by some other means before the isolator can be opened as its breaking capability is ZERO Amps.

A fuse is a non switchable device which is designed for circuit protection rather than control. A fuse of a given rating will carry the current of that rating continuously but if the current goes above that value, the fuse will rupture and disconnect the load. How long it takes for the fuse to rupture is a dependent on how much above the rating the current that is flowing in the circuit is. As a rough example,  if the current is twice that of the rating the fuse may take a a few minutes, even an hour to rupture depending on the particular characteristic. If the current is twenty times the rating the the fuse will rupture in a a fraction of a second.

Fuses may be in holders with removeable carriers or bolted into a circuit. If in a holder, they can be used for isolation purposes as a removed fuse shows a visible break in the circuit. However a fuse should never be removed from a energised circuit. Doing so could result in the drawing of an arc which may damage equipment or be fatal to the remover.

 

Hope that this helps.

Good luck with your studies

[Sudeep]

@Smithy: I deleted your duplicate post…

Thank you for your help!

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