Eight town Bid. (part 3)
Treatment plant control.
Treatment plant control is provided by PLC consists from CPU module EMS 015 and three I/O blocks.
The CPU module is a computer with RAM and ROM memory, a fully- functional and fast processor, a real-time clock and serial data I/ O ports. Using an advanced version of the familiar Ladder Logic language programs the CPU. The CPU module is the core of the treatment plant PLC. The module contains the operating system code, provides RAM for run- time variables and historical data and provides FLASH memory for the Application Program.
The C programming language may be used to code functions and routines which may be compiled and downloaded into the CPU. The CPU module may use some third- party protocol for its communication needs. These protocols include MODBUS, X. 25, and others.
I/O blocks provide informational capacity of IOs to meet control demands for treatment plant.
The I/O block is named EMS016. The I/O block main function is an analogue to discrete conversion and root-mean-square (RMS) value calculation for any signal waveforms. This block has static RAM memory and can by configure for primary data filtration. The I/O block also can store signal waveform and analyze signal correlation. The I/O block provides the data acquisition and control functions by IEC 807-5-103, DNP 3.0, MODBUS and etc protocols. It has high-speed serial port for IEDs (relay protection units, etc.) connection. It provides a communication rate up to 115 kbps.
Each I/O block has eight-bit switch for address located on the printed circuit.
The EMS016 family controllers are created for distributed data acquisition systems and execute next functions:
• analogue input and output
• discrete input and output
• primary data conversion
• control command executing
• data exchange
|quantity of analogue inputs (TM)||16||4-20 mA, 0-5 mA, 0-10 B|
|ADC resolution||10|| |
|quantity of discrete inputs (TS)||48||24 V input|
|quantity of discrete outputs (TC)||16||relay 6A, 250V|
|flash memory capacity||32||Kbytes|
|interface types|| || CAN, RS485, I ² C, RS232|
|quantity of counter’s inputs||32||0-100 kHz|
|event list capacity||256||Notes|
|event list store time (without external power supply)||10||years|
Discrete inputs (TS)
The discrete inputs are connecting with dry contact relays or control switches. The 24 volts galvanic detached power source is applying for relay contact self-cleaning purposes. The all signal inputs has galvanic isolation and can be used as frequency or pulse inputs.
Analogue inputs (TM)
The analog inputs are connecting with measuring equipment with 4-20 mA, 0-5 mA or 0-10V outputs. The input signals are scaling, converting in ADC and then transmitting via station bus. The feature of this block is a secondary parameter calculation and analyzes. All analog inputs have surge and overstress CLAMPDOWN™ protection.
Discrete outputs (TC)
The control outputs are presented as relays contacts. Relays are located in control cubicle on DIN-rail. Outputs from the I/O block are protected OK drivers’ outputs.
The I/O block is supplied from AC 220 V, 50 Hz. The internal power supply subblock converts input AC voltage in DC voltage to supplying:
• -I/O block
• -sensors power supply
• -control relay’s power supply
The power supply subblock has surge and overstress CLAMPDOWN™ protection. This configuration provides high durability and guaranty high reliable power supply for equipment.
The I/O block is placed in metal cabinet and can be mounted on DIN rail. The two bus connectors and four power 48 pins connectors for I/O terminals are located on the front side of the cabinet. The I/O block face side has three LED indicators:
These controllers are mounted in control cubicle.
The pre-engineered cable-and-terminal block assemblies replace independently wired marshalling blocks and I/O connectors, and they eliminate point-to-point wiring checkout at this level. The cable is prewired at both ends and was purchased for the project already fused and in lengths tailored to the cabinet layouts.
Should communications with any of the remote station fail the local PLC will assume control and follow predetermined instructions that vary from season to season.
Using UHF Simplex radios, the PLCs communicate with the PC plant. The process of receiving necessary FCC licenses is very simple.
With the SCADA radio system up and running is clearly achieved its goals of reducing communications system cost, reducing the operations and maintenance costs associated with running the SCADA system, and simultaneously improving system reliability.
The communication software
As main communication software we applying “Object manager v2.4”. This software answered for next requirements:
• -communication via many difference devices in same time
• -using difference protocols in same time
• -construction one object from difference data sources
• -high stable algorithm based on POSIX subsystem
• -short time for any algorithm changing
The communication model based on three layers of abstraction:
• -communication task
• -communication device
The object collects and keeps all object state information in standard.
The communication task realizes specific communication algorithm and data exchange protocol for information source or destination.
The communication device realizes device specific algorithm, channel or frequency selection and divide time between communication tasks. Each communication task independently communicates via communication device and can change device at any time.
For authority users accepts to run system utilities as described below. (All system utilities protected by supervisor password)
Administration tools include next utilities:
• configuration manager
• event viewer
• communication statistic viewer
The configuration manager accepts to edit object manager configuration.
The event viewer accepts to view all communication and system events for analyze.
The communication statistic viewer accepts to view communication statistic databases and detecting communication channels faults.
Diagnostic tools include next utilities:
• communication test tool
• configuration diagnostic tool
• database configuration tool
The communication test tool accepts to estimate channel quality and adjust aerial direction.
The configuration diagnostic tool accepts to optimize object manager configuration and check it for configuration format errors.
The database configuration tool accepts to check for database errors and pack or delete old database records.
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