ABB MEASUREMENT & ANALYTICS TZIDC-220 Digital Positioner

Brief description

The TZIDC-220 is an electronically configurable positioner

with communication capabilities designed for mounting on

pneumatic linear or rotary 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 positioner allow for considerable time

savings as well as optimum control behavior.

Pneumatics

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.

Dosing of the air flow for pressurizing or depressurizing the

actuator is continuously adjusted. As a result, excellent

control results are achieved. When reaching the setpoint, the

3/3-way valve is closed in center position to minimize the air

consumption.

The pneumatic system can be supplied in four versions: for

single acting and double acting actuators and each with the

‘fail-safe’ / ‘fail-freeze’ safety function.

‘Fail-safe’ safety function

If the electric power supply fails, the positioner output 1 is

depressurized and the return spring in the pneumatic

actuator moves the valve to the safe position. In case of a

‘double-acting’ version, output 2 is additionally pressurized.

‘Fail-freeze’ function

If the electric power supply fails, the positioner Output 1

(and Output 2 if applicable) is closed and the pneumatic

actuator blocks the valve in the current position. If the

compressed air supply power fails, the positioner

depressurizes the actuator.