WATER TREATMENT FACILITY UPGRADE
HART transmitters and a control system with HART capability were chosen to upgrade a water treatment facility. The completed
installation reduced capital, engineering, and installation costs. The process dynamics of the water treatment facility allowed the HART instruments to be used in all-digital mode without compromising plant performance.
The water treatment plant
is divided into two areas, each with 14 filters. Each area is controlled by a separate control system for complete autonomy. A HART network monitors each filter for filter level,
filter bed differential, and filter outlet flow. The multidrop installation used a
three-wire system in order to accommodate both the two-wire and the four-wire devices (magnetic flowmeters) in use (Figure 23)
(see
Multidrop on page 6).
Figure 23: Multidrop Networks with 2-Wire and 4-Wire
Devices
Because the water treatment facility had a modular design, the use of HART instruments allowed the configuration from the one filter network
to be copied to the others, which reduced the implementation time.
Engineering, system configuration,
drafting, commissioning,
maintenance, and documentation were simplified. A reduced I/O card count also saved money.
IMPROVED DIAGNOSTICS
A cleaning materials supplier required periodic checkup of the instrument condition and configuration information as compared to the initial installation. The field transmitters provided a historical record of status changes along with current configuration information. Periodic download of this information was made possible using PLC ladder logic developed for HART instruments.
