Setra’s Model 278 barometric pressure
transducer is designed for use in
environmental applications that require
excellent accuracy, fast dynamic response, and
long-term stability and reliability.
To withstand the environmental extremes
typically found in Automated Weather
Station (AWS) and environmental monitoring
applications, the Model 278 housing is constructed
of stainless steel and polyester. A removable
5-pin terminal strip module is provided
for easy connection to data logger
and signal connections, and a 1/8” Barbed
fitting is used for pressure connection. The
transducer’s footprint (3.6” x 2.4” x 1.0”) makes
it ideal for use as a new or drop-in
replacement to existing configurations.
The Model 278 is operable in temperatures
from -40°C to +60°C (-40°F to +140°F). Users
may choose 0 to 2.5 VDC or 0 to 5 VDC
output, a 3 or 4 wire circuit and an excitation
range of 9.5 to 28 VDC.
This unit consumes low levels of power (3mA
nominal) while in operation. Its sleep mode
feature reduces power consumption to 1 µA, and
provides instant startup for applications where
pressure readings must be taken quickly.
Principles of Operation
The Model 278 utilizes Setra’s Setraceram™
capacitive sensor and proprietary custom IC
analog circuit. This fundamentally simple design
and thermally stable glass fused ceramic sensing
capsule is coupled with Setra’s sophisticated
capacitance charge-balance IC circuit where
accurate signal conditioning and environmental
compensation is performed. The Setraceram™
sensor provides excellent thermal expansion
coefficient and low mechanical hysteresis,
which contributes to the long-term stability of
the Model 278.
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