Circuit breakers, disconnectors
Circuit breakers and disconnectors are a large group of electrical
devices which, having some common features, differ from each other in
terms of their structure and functionality. Together with disconnectors,
circuit breakers and disconnectors fall into a common category of
switches designed to connect electrical circuits in their own way.
Circuit breakers and disconnectors in networks and installations
Circuit breakers are equipped with extinguishing chambers, which
enable them to switch off overcurrents, while disconnectors are used
to disconnect operating currents with a maximum intensity equal to the
rated intensity. Switch disconnectors are not suitable for breaking
overcurrents. In order to categorize circuit breakers, various criteria
can be adopted, e.g. electric power or the medium used to extinguish an
electric arc.
Molded case circuit breakers
Molded case circuit breakers are also called power circuit breakers.
They are used in circuits whose receivers are characterized by high
electrical power. They are used to control the flow of power in an
electrical installation (mainly industrial) or network, as well as
protect other circuits and devices against the effects of short circuits
and overloads. Molded case circuit breakers are characterized by several
parameters:
- rated voltage,
- rated current,
- short-circuit current,
- permissible operating temperature,
- way to extinguish the arc.
Circuit-breakers can be classified according to their voltage into low,
medium and high voltage. In turn, taking into account the method of
extinguishing the arc, we distinguish, among others air circuit
breakers , sulfur hexafluoride, vacuum or pneumatic. Usually, the
specific method of arc extinguishing is related to the voltage at which
the circuit breaker works, but now the division is not as obvious as it
used to be. Today you can buy, for example, an air circuit breaker of
both high and low voltage.
Circuit breakers, switch disconnectors and disconnectors, or electrical switches
Switches are electrical devices that are used to transfer operating
currents as well as short-term overload and short-circuit currents. They
include:
- disconnectors,
- disconnectors,
- switches.
Disconnectors are devices that do not have the ability to turn on and
off the electricity - they are used to increase the safety of works with
power devices. The disconnectors can switch operating and overload
currents, but they cannot switch short-circuit currents. On the other
hand, the circuit breakers (which include not only the compact circuit
breakers described above) can switch on and off the operating, overload
and short-circuit currents.
The most popular electrical connectors
The most frequently used switches in residential and industrial
installations include screw and panel switches, as well as overcurrent
circuit breakers (abbreviated as redundant), i.e. popular, commonly used
so-called Modular construction, usually manufactured for rated currents
from 0.3 A to 63 A, rated alternating current voltages of 230 and 400 V
and direct current voltages of 60 and 110 V, as well as rated
short-circuit capacity of 10kA. Selective switches are also important in
electrical installations, as they ensure the selectivity of protections
in relation to the overcurrent switches located behind them (from the
power supply side).
Another group are motor circuit breakers , which are designed to
protect motors against the effects of overcurrents (overloads or short
circuits). They enable manual switching on and off, while switching off,
as in the case of other switches - is also always automatic. A separate
group consists of residual current devices, most often in the form of
residual current blocks.
Manual switches are another category, which includes, for example,
manual panel disconnectors, but also RIN or FR type switches, as well as
cam switches . The latter are intended for switching on and off
operating currents occurring during the control and connection of motors
and other electrical receivers. Next in the category of switches are
mechanical switches, contactors and finally installation fuses.
