The Power plant will be monitored and controlled by DCS.

The instrumentation and system for the project is a microprocessor-based distributed control system. The distributed control system is designed to provide:

- High reliability

- Failsafe operation

- Capability of being upgraded

- High productivity

- Safety for equipment and personnel

- Minimum number of discrete display and recording instruments

The distributed control system includes the following functionally distributed subsystem:

- Distributed digital control for closed loops

- Programmable logic controller for open-loop controls

- Operator console (unit control board)

- Process data acquisition

- Supervision subsystem (engineer console)

- Programming subsystem

- Historical data storage, retrieval, and calculation subsystem

These subsystem are designed to ensure:

- One to two-second response time

- 100 ms data update rate

- 1 ms data resolution for sequence of events points

The distributed control system includes adequate redundancy at various levels. The system is designed for “fail-safe�?operation and is in full conformity with the specifications and recommendations of codes and standards of recognized international technical bodies and institutes.

In general, most of instruments composing the main control loops for plant operation will be electronic type.

Regarding those control loops which are not critical or which do not require precise control, local pneumatic instruments will be used. The standard electronic signal level of 4-20 mA DC will be used for instruments. The power supply for instruments will be 220 V AC and 24 V DC. 

Annunciator system, in accordance with specific requirements, will be provided so that abnormalities in critical systems can be observed. 

The entire system will be so designed that systematic overall operation may be possible with a small complement of operators. 

Each final control drive and/or control valve will be furnished with an electronic/pneumatic positioner where applicable to operate a pneumatic actuator capable of working on an air supply pressure. 

Supervisory instruments (such as indicators, recorders, integrators), controllers, and annunciators will be mounted on control panels. Important control components such as remote control switches, indicating lamps, emergency stop buttons and annunciator test/acknowledge/reset buttons will be also mounted on control panel. 

Main functional instruments such as controllers, various computing relays, alarm setters, signal converters, and power supply units will be mounted insides the control panel. 

In the control room thermo-parameters and equipment will be supervised, controlled in normal operation and treated in emergency.

8.2 Scope of supply

All necessary field instruments, transmitters, control valves, on-off valves, motor valves, auxiliary equipment, wire and cables, installation materials.

DCS system, include necessary hardware and software.

PLC system, include necessary hardware and software.

All instrumentation engineering documents.

8.3 Engineering standard of instrumentation

Standard signal

- Electronic standard signal: 4~20 mADC

- Pneumatic standard signal: 0.02~0.1 Mpa

All materials will be suitable for process requirement.

Standard power supply is 220VAC, 50Hz, single phase, or 380VAC 50Hz, three phases.

Signal cable will be shield cable, 1.0mm².

Air supply tube will be nylon, D6x1 or D8x1.

Instrument pulse pipe will be stainless steel, D14x1.

Temperature measurement

- Up to 300�? resistance temperature detector Pt100 or bimetallic thermometer.

- Over 300�? thermocouple will be used

- Normally integrated temperature transmitter will be used.

Pressure measurement

- Pressure gauges

- Normally pressure transmitter

- Pressure transmitters with diaphragm

- Diaphragm pressure transmitter with capillary

Level measurement

- Float level indicator

- Level switch

- Level transmitter with diaphragm

- DP transmitter

Flow measurement

- Water flow meter

- Throttling device and DP transmitter

- Magnetic flow meter

- Flow switch

- Vortex flow meter

8.5 DCS system specification

The DCS system is standardized and of rigid design for location in industrial control room. The system includes necessary display for operation and dynamic process information, and also safety interlocking, alarms. “Trends�?display can be used for easy process check-up; alarms and report can be printed via printers in control room.

The DCS includes 3 operator stations (OS), one of OS will be also use as engineering station, and also include 2 printers.

Open system structure, easily expanding in future.

Use of only one engineering tool for configuring the automation functions and the operator interface with displays and logs.

Automatic generation of the entire communication between process and operator stations.

Lower cost and time investment for data input due to a system uniform database for process and operator stations, leading to data consistency within the entire system.

The operating system for DCS will be based on Microsoft Windows NT, it is convenient for operator training and operating, and also easily for engineering configuration.

The engineer station located in each control room will do the configuration of DCS system.

The operator and engineer station will be at least P4/2.0GHz, and 256M RAM, 19"CRT

8.6 Turbine generator instrument list