Brochure

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SOLID STATE RELAYS IN COMMERCIAL
HVAC APPLICATIONS
Background
HVAC systems can be found almost anywhere
to provide thermal comfort to people inside
homes and buildings. Outside climates can
vary wildly so these systems are required to
maintain inside temperature in a comfortable
level and provide good indoor air quality.
One of the main types of HVAC systems
used are the ones called Air Handlers (AHU),
which are used mainly in medium to large
commercial and industrial buildings. These
systems are typically mounted in the ceiling
and they take outside air, lter it, heat it or cool
it, dehumidify it if necessary and then distribute
it through ducts across one or several sections
of the building.
Air handlers normally consist of large metal
boxes containing several different components
such as blowers, lters, heating/cooling
elements, dampers and
in some cases, heat
exchange devices.
Solution
Sensata offers a wide range of solid state relays
and contactors that can be used in commercial
HVAC systems to keep them running smoothly
and reliably. A lot of these systems still use
electromechanical contactors and relays while
some older systems even make use of mercury
displacement relays (MDR), due to their higher
life expectancy compared to traditional EMRs,
but these are being discontinued due to the
toxicity of that substance.
Solid state relays offer many advantages
when used in these systems, such as long
life expectancy, no mechanical noise, low
input current and fast response, so they are
well suited for replacing these older switching
technologies.
SSRs can handle almost any type of load
used in HVAC systems, such as fans/blowers,
motors, compressors and they are perfect
for use in heating control applications, where
there is a requirement to switch electric heating
elements on and off constantly to maintain a
certain temperature. In some cases, a more
precise temperature control can be achieved
by using a proportional power control method
such as phase angle control or burst re
control, which can only be done using a solid
state device.
APPLICATION NOTE
SSRs can handle almost
any type of load used in
HVAC systems and they are
perfect for use in heating
control applications.