How Circuit Breakers Work:
The simplest circuit protection device is the fuse.
A fuse is just a thin wire,
enclosed in a casing, that
plugs into the circuit. When a circuit is closed, all
charge flows through the fuse wire -- the fuse
experiences the same current as any other point
along the circuit. The fuse is designed to disintegrate when it heats up above a certain level
-- if the current climbs too high, it burns up the
wire. Destroying the fuse opens the circuit before
the excess current can damage the building wiring.
The problem with fuses is they only work once.
Every time you blow a fuse, you have to replace it with a new one. A circuit breaker does the same
thing as a fuse -- it opens a circuit as soon as
current climbs to unsafe levels -- but you can use it
over and over again.
2. The basic circuit breaker consists of a simple
switch, connected to either a bimetallic strip or an electromagnet. The diagram below shows a
typical electromagnet design. The hot wire in the circuit connects to the two
ends of the switch. When the switch is flipped to
the on position, electricity can flow from the
bottom terminal, through the electromagnet, up to
the moving contact, across to the stationary
contact and out to the upper terminal. The electricity magnetizes the electromagnet (See
How Electromagnets Work to find out why).
Increasing current boosts the electromagnet's
magnetic force, and decreasing current lowers the
magnetism. When the current jumps to unsafe
levels, the electromagnet is strong enough to pull down a metal lever connected to the switch
linkage. The entire linkage shifts, tilting the moving
contact away from the stationary contact to
break the circuit. The electricity shuts off.
Click on the circuit breaker to release the switch.
A bimetallic strip design works on the same principle, except that instead of energizing an
electromagnet, the high current bends a thin strip
to move the linkage. Some circuit breakers use an
explosive charge to throw the switch. When
current rises above a certain level, it ignites
explosive material, which drives a piston to open the switch.
plugs into the circuit. When a circuit is closed, all
charge flows through the fuse wire -- the fuse
experiences the same current as any other point
along the circuit. The fuse is designed to disintegrate when it heats up above a certain level
-- if the current climbs too high, it burns up the
wire. Destroying the fuse opens the circuit before
the excess current can damage the building wiring.
The problem with fuses is they only work once.
Every time you blow a fuse, you have to replace it with a new one. A circuit breaker does the same
thing as a fuse -- it opens a circuit as soon as
current climbs to unsafe levels -- but you can use it
over and over again.
2. The basic circuit breaker consists of a simple
switch, connected to either a bimetallic strip or an electromagnet. The diagram below shows a
typical electromagnet design. The hot wire in the circuit connects to the two
ends of the switch. When the switch is flipped to
the on position, electricity can flow from the
bottom terminal, through the electromagnet, up to
the moving contact, across to the stationary
contact and out to the upper terminal. The electricity magnetizes the electromagnet (See
How Electromagnets Work to find out why).
Increasing current boosts the electromagnet's
magnetic force, and decreasing current lowers the
magnetism. When the current jumps to unsafe
levels, the electromagnet is strong enough to pull down a metal lever connected to the switch
linkage. The entire linkage shifts, tilting the moving
contact away from the stationary contact to
break the circuit. The electricity shuts off.
Click on the circuit breaker to release the switch.
A bimetallic strip design works on the same principle, except that instead of energizing an
electromagnet, the high current bends a thin strip
to move the linkage. Some circuit breakers use an
explosive charge to throw the switch. When
current rises above a certain level, it ignites
explosive material, which drives a piston to open the switch.
About the Author
I am Kashif Mirza, the founder of Student Training Lab (STL). I am working on projects since 2005 before that I just search things and now I am sharing my knowledge through this plateform.
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