07-12-2012, 10:58 AM
CIRCUIT BREAKER INTRODUCTION
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Introduction
Any electrical or electronic equipment that is designed without
including circuit protection is an accident waiting to happen.
Under normal operating conditions, this may not appear to be a
problem. However, normal operating conditions are not always
guaranteed. Under strained or heavy use, a motor and/or another
load-generating component within the equipment will draw
additional current from the power source; when this happens,
the equipment’s wires and/or components will overheat and may
ultimately burn up. Also, power surges and short circuits in
unprotected equipment can cause extensive damage to the
equipment and to the conductors leading to the equipment.
In addition to protecting the equipment, the entire electrical system
including the control switches, wires, and power source
must be protected from faults. A circuit protection device should
be employed at any point where a conductor size changes.
Many electronic circuits and components like transformers have
a lower overload withstand threshold level than conductors such
as wires and cables. These components require circuit protection
devices featuring very fast overload sensing and opening
capabilities.
Specifying a circuit protection device for an application is not a
difficult task, but it will require some thought. If electrical and
electronic equipment is designed with over-specified circuit protection
devices they will be vulnerable to the damaging effects of
power surges and the catastrophic results of a fire; while using
under-specified circuit protection devices will result in nuisance
tripping.
Available Choices of Circuit Protection
Carling Technologies offers three types of circuit protection
devices: thermal circuit protectors, hydraulic/magnetic circuit protectors/
breakers and equipment leakage circuit breakers. This
catalog features hydraulic/magnetic circuit protection and equipment
leakage circuit breaker products. For details related to our
thermal circuit protection product line, please see our thermal
circuit protection catalog.
Thermal circuit protectors utilize a bimetallic strip electrically in
series with the circuit. The heat generated by the current during
an overload deforms the bimetallic strip and trips the breaker.
Thermal protectors have a significant advantage over fuses in
that they can be reset after tripping. They can also be used as
the main ON/OFF switch for the equipment being protected.
However, thermal breakers have some disadvantages. They are,
in effect, "heat sensing" devices, and can be adversely affected
by changes in ambient temperature. When operating in a cold
environment, they will trip at a higher current level. When operating
in a hot environment, they will "nuisance trip" at a lower
current level resulting in unwanted equipment shut downs.
Carling Technologies’ Hydraulic/Magnetic Circuit Breakers
Carling Technologies’ hydraulic/magnetic circuit breakers are current sensing devices employing a time proven hydraulic magnetic
design. Their precision mechanisms are temperature stable and are not adversely affected by temperature changes in their operating
environment. As such, derating considerations due to temperature variations are not normally required, and heat-induced nuisance
tripping is avoided.
Features
Carling Technologies’ Hydraulic/Magnetic Circuit Breakers
• A trip-free mechanism, a safety feature, makes it impossible
to manually hold the contacts closed during overcurrent
or fault conditions.
• Worldwide safety agency approvals are available.
• Current ratings to 700 Amps and rated voltages to 600 VAC
are available.
• A common trip linkage between all poles, another safety
feature, ensures that an overload in one pole will trip all
adjacent poles.
• Industry standard dimensions, mounting and current ratings
provide maximum application versatility.