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Read the text and underline or highlight the key points
CIRCUIT BREAKERS AND SWITCHES
A circuit breaker is an electromagnetic device that opens the circuit
automatically when the current exceeds a predetermined value. It can be reset
operating a lever or by other means. A switch is a manually, or mechanically,
electrically or electronically actuated device for making, breaking, or changing
the connections in an electric circuit. Their function, to put it simple, is to
protect the circuit in which they are built from possible damages. They are
designed to interrupt excess current that can overload the electrical wires, and
they cut off the circuit whenever the current jumps above a safe level.
A circuit breaker, unlike a fuse, which operates once and then has to be
replaced, can be reset (either manually or automatically) to resume normal
operation. The choice of a proper circuit breaker depends on the particular
application, i.e. it may be a small device used for protecting individual
household appliance, or a large switchgear designed to protect high voltage
circuits feeding an entire city. A circuit breaker is required to
withstand the maximum voltage stress,
carry rated current continuously without damage,
have sufficient interrupting capacity,
be suitable for operation in the intended environment
provide the protective function or protective and control functions if
needed.
There are many types of switches available
f
or electric circuits. All
switches perform the same basic function of opening or closing circuits. The
type used in a given application is often a matter of style and/or convenience of
operation. When the switching requirements are complex, the choice narrows to
the rotary switch. On the other hand, simple switches, such as toggles, slides,
rockers, levers etc, usually control only one or two circuit paths. Some switches
are constructed so that they always return to the same position when released by
the operator. There are also safety switches which look similar to circuit
breakers, but they provide extra protection from electric shock. Safety switches
monitor the flow of electricity and if any irregularity is detected, the electricity
supply is immediately cut off.
Work in pairs. Turn to your partner and recite the key points
Make notes from the information you have highlighted or underlines.
Organize them logically, and be concise
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