Why using of circuit breaker?

Answer 1

Circuit breakers - and fuses - were both invented to protect electrical items from being damaged by taking too much current (amps), something which is also known as an over-current fault condition. How a circuit breaker works

When an over-current fault condition occurs, which is the same as saying the current gets bigger than the circuit breaker was designed to carry, it's mechanism causes its switch contacts to open, which cuts off the supply of current. When that happens the circuit breaker is said to "trip".

When whatever fault condition in the protected circuit has been repaired, the circuit breaker can be "Reset" by pressing a button to close its switch contacts. The contacts should then remain closed until another over-current fault condition occurs in the circuit it is protecting, which would cause the breaker to trip again.

What are the advantages and disadvantages of circuit breakers?

To give the same over-current protection, circuit breakers can be designed to trip much faster than an ordinary fuse but they are generally larger in size and cost more to make.

However circuit breakers are reusable and can easily be reset after they have tripped - provided, of course, that the fault condition in the protected circuit has been repaired.

A fuse is a protective device that destructively opens when the current flow exceeds a preset value. It is usually designed as a low value resistor that heats up and melts at the specified current value. Once the fuse blows, it must be replaced.

A circuit breaker is a protective device than non-destructively opens when the current flow exceeds a preset value. It is usually designed as a tripping relay/switch that can be reset and reclosed when the fault is cleared.

In both cases, the design can provide for different preset values as a function of time. It depends on whether the intended load pulls a larger startup current than when it runs, such as a motor, which can easily pull four times their run current when they startup. The protective device is selected for the specific type of load, and for the rating of the conductors supplying it.

How a fuse works

When an over-current fault condition occurs, which is the same as saying the current gets bigger than the fuse can carry, its internal "fuse wire" gets so hot that it melts and breaks apart, which cuts off the supply of current. When that happens the fuse is said to have "blown".

After whatever caused the over-current fault condition in the circuit has been repaired, a blown fuse must either be replaced with a new one or, if it is the type of fuse which can be rewired, it must be repaired using the correct size of special "fuse wire".

A new fuse should then remain in place un-blown until another over-current fault condition occurs in the circuit it is protecting, which would then cause the new fuse to blow.

What are the advantages and disadvantages of fuses?

To give the same over-current protection, fuses are generally cheaper to make and smaller in size than circuit breakers.

However an ordinary fuse cannot blow as quickly as a circuit breaker can "trip".

Some equipment may require special "quick-blow" fuses so that damage can be prevented when an over-current fault condition occurs. Quick-blow fuses cost much more to make than ordinary fuses but must sometimes be used where a circuit breaker would be too expensive and/or too large in size.

Further notes about fuses:

• Some fuses are rewireable, meaning they can be repaired if they blow. This must only be done using new fuse wire of the correct size. It is dangerous to use fuse wire which is thicker than the size marked on the rewireable fuse's body.
• Other fuses, known as "one-time" or "cartridge" fuses, cannot be repaired when they blow. If that happens they must be thrown away and replaced by a new fuse of the correct size.

  Some one-time fuses look like small cylinders with a metal cap at each end; others look like a small cylinder with a metal screw-cap on one end like a light bulb. One-time fuses for vehicles, known as "fuse-links", have small bodies made of plastic and two metal blades which push into fuse slots in the vehicle's fuse box.

  If a one-time fuse blows it should only be replaced by a new one of the correct size (Amps) for the circuit. The ones which screw in have different sized screw-caps for each size of fuse, with matching sockets to ensure that only a fuse which is the correct size can be screwed into the fuse holder. Similarly, fuse-links have different sized metal blades and matching slots to ensure that a given slot can only accept the correct size of fuse link.

Answer 2

A breaker is important because it serves the same purpose as a fuse. The only difference is that you can reset a breaker if it blows instead of replacing a fuse. Older houses are usually wired with fuses and you need to replace them each time they blow; however, breakers just trips off when the current becomes too great. Each breaker has its own set current limit so if the amperage breaks that limit, it therefore pops and turns off in order to prevent damage or even fire in some cases.

Answer 3

A circuit breaker protects the devices and wiring that is a permanent part of the circuit. Devices you connect to the circuit externally should be protected by their own over-current devices. If you didn't have a breaker and there was a short circuit inside your house then your house would try and draw all the current available from the power company until breaker up the line started tripping. By that time your house might already be burning down.

Answer 4

The circuit breaker protects the wire from getting too much current. Too much current could cause the wires to over heat and possibly start a fire. The size of the wire determines the number of amps that the wire can handle safely, so the number of amps on your circuit breaker should be based on the size of the wire.

Answer 5

An electrical breaker or circuit breaker is used to protect appliances and electrical devices from damage caused by short circuits and electrical overloads. It basically detects a defect in the system and then interrupts the flow of current.

Answer 6

A circuit breaker is used to ensure that the circuit doesn't get overloaded with too much wattage or voltage, which can cause a fire.

Answer 7

Breaker or circuit breaker is a switch operated automatically by electricity. Breakers are designed to protect or to prevent an electrical circuit from short circuit or overloading.