An I/P module with subsequent pneumatic amplifier is used to control the pneumatic actuator. The well-proven I/P module proportionally converts the permanent electrical setpoint signal from the CPU into a pneumatic signal used to adjust a 3/3- way valve. The air flow for pressurizing or depressurizing the actuator is continuously adjusted. As a result, excellent control is achieved. When reaching the setpoint, the 3/3-way valve is closed in center position to minimize the air consumption. Four different pneumatics versions are available: for singleacting or double-acting actuators, each with "fail-safe" or "failfreeze" function.
If the electrical supply power fails, the positioner output 1 is depressurized, and the pneumatic actuator’s return spring moves the valve to the defined safe position. In case of a double-acting actuator the second output 2 is additionally pressurized.
If the electrical supply power fails, the positioner output 1 (and 2, if applicable) is closed and the pneumatic actuator stops ("freezes") the valve in the current position. If the compressed air supply power fails, the positioner depressurizes the actuator.
The positioner has a built-in operating panel providing a 2-line LCD display and 4 operating buttons for commissioning, configuration and monitoring during live operation. Alternatively, the appropriate configuration program can be used via the available communication interface.
The positioner has a local communication interface (LCI) as standard. Additionally, a "HART communication" option for communication via the 20 mA signal is available. Both communications are based on the HART Protocol. Alternatively, HART5 or HART7 are available.
Inputs / Outputs
In addition to its input for the analog position setpoint, the positioner is equipped with a digital input which can be used to activate control system functions in the device. A digital output allows you to output collective alarms or fault messages.
The basic model can be enhanced at any time by retrofitting optional equipment. Option modules can be installed for analog and digital position feedback. Additionally, a mechanical position indicator, proximity switches or 24 V microswitches are available for indicating the position independently of the mother board function.
ABB Digital Positioner
The TZIDC-200 is an electronically configurable positioner with communication capabilities designed for mounting to pneumatic linear or part-turn actuators. It features a small and compact design, a modular construction, and an excellent cost-performance ratio. Fully automatic determination of the control parameters and adaptation to the final control element yield considerable time savings and an optimal control behavior.
Microprocessor-based position control in the positioner optimizes control. The positioner features high-precision control functions and high operational reliability. Due to their elaborate structure and easy accessibility, the device parameters can be quickly adapted to the respective application.