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STI S.r.l. – Via Dei Caravaggi 15, 24040 Levate (BG) – ITALY www.imi-critical.com
Manual 4054 – rev.00 02/2021 – DT2 - 5 -
2. DESCRIPTION
DT2 Intelligent Electro pneumatic Positioner is a loop powered instrument produced by STI s.r.l. As a control part of the
pneumatic valve set, DT2 Intelligent Electro pneumatic valve Positioner is widely used in petroleum, chemical, electric
power, metallurgy, paper, light industry and other fields of automation systems.
DT2 Intelligent Electro pneumatic valve Positioner accepts the 4÷20mA valve setting signal from the control system; at
the same time, it gets the actual valve signal through the location sensors; the two signals are compared by instrument
software in order to control the feeding and exhaust of the gas to actuator, driving the valve to reach set point (as
Figure 1).
DT2 Intelligent Electro pneumatic valve Positioner is based on microprocessor technology. It can overcome friction and
the imbalance power on the control valve well, and improve the response speed of control valve, which makes the
position set rapidly and accurately. It is not only able to completely substitute conventional valve positioner, but also is
able to directly access HART network, exchanging information between control system and positioner.
Figure 1: DT2 Intelligent Electropneumatic valve Positioner Principle
2.1 Description of Function instruction
• Self-adaptive function: automatic search the Zero and Span of valve, optimize the valve’s control parameters
and improve the control precision.
• Configuration function: valve characteristics curve, action mode, dead band, stroke range, shut-off value and
alarm events.
• Self-diagnosis function: show the value of setpoint current, travel time, and dead band.
• Fault mode function: Fail safe or fail freeze.
• Communication function: HART communication protocol.
• Valve position feedback function: 4~20mA DC valve position feedback signal, switch valve feedback signal.
2.2 Performance
• Position precision: 0.5% F.S.
• Manual setting operation allowed directly on the positioner, without opening the cover.
• Simple and compact design, modular construction.
• Automatic initialization, automatic diagnosis, valve characteristic curve.
• Reduced number of mechanical parts, good vibration resistance performance.
• Local or remote parameter setting.
• Low power, low air consumption, low running cost.
• Two-wire supply in 4-20mA standard.
• Integrated lighting protection module can be used to reduce the damage probability, due to surge of lighting.
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