GE DewPro MMY31, Инструкция по установке и эксплуатации

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General System Information 1-3
September 2005
Unit Description
The DewPro MMY31 trace moisture transmitter is a loop-powered
dewpoint measuring device. The transmitter includes a sensor
element, a stainless steel probe, a weather-proof enclosure,
microprocessor electronics, and assorted fittings, all in a compact
assembly. It is designed to be installed “in-line.” Various types of
mounting hardware, such as flange and compression fittings, are
available for mounting into a process chamber or pipe.
An optional display with user interface feature allows the DewPro to
be configured by the user. See Chapter 4 for more information.
Theory of Operation
4–20mA Loop
The DewPro MMY31 microcontroller operated electronics works
with a voltage supply of 12 to 28 VDC. At the nominal 24 VDC
supply, the maximum loop resistance is 600 ohms. The signal is
represented by the 4–20 mA loop current and is directly proportional
to the dewpoint temperature range in °C or °F. In the standard range,
4 mA corresponts to –90°C (–130°F) and 20 mA to +10°C (+50°F)
dewpoint temperature. The optional unit of measure is ppm
v
in the
standard range 0-100 ppm
v
, unless ordered differently
Planar Sensor
The heart of the MMY31 is the planar sensor element. It incorporates
a superior aluminum oxide sensor that provides longer calibration
stability, excellent corrosion resistance, and improved speed of
response. The sensor, mounted on a ceramic substrate, also has a
reduced temperature coefficient.
Calibration
Each DewPro is factory calibrated against precise NIST certified
moisture references and has an accuracy of ±2°C dewpoint at 25°C
temperature. For field validation, GE Sensing offers a unique
validation device. The MMY245 field validator connects to the
DewPro on site and offers a one-point or two-point correction.