27-10-2012, 04:58 PM
A TECHNICAL PAPER ON SCADA TECHNOLOGY
SCADATECHNOLOGY.pdf (Size: 233.26 KB / Downloads: 29)
INDRODUCTION
Widely used in industry for Supervisory Control and Data Acquisition of
industrial processes, SCADA systems are now also penetrating the experimental physics
laboratories for the controls of ancillary systems such as cooling, ventilation, power
distribution, etc. More recently they were also applied for the controls of smaller size
particle detectors such as the L3 muon detector and the NA48.
SCADA systems have made substantial progress over the recent years in terms of
functionality, scalability, performance and openness such that they are an alternative to in
house development even for very demanding and complex control systems as those of
physics experiments.
EVOLUTION:
Phonetics created the SENSAPHONE SCADA 3000, a Y2K-complaint hardware
and software system design to accommodate small to mid-size companies seeking
SCADA control. The system main unit uses two microprocessors to perform all control
and communication functions. In terms of hard ware, the standard SENASAPHONE
SCADA 3000 is equipped with 16 universal inputs, eight relay outputs, two RS-232 ports
for local programming and radio communications, and a four line by 20-characters LCD.
WHAT DOES SCADA MEAN?
SCADA stands for Supervisory Control and Data Acquisition, it is a computer
system for gathering and analyzing “real time data” SCADA systems are used to monitor
and control a plant or equipment in industries.
SCADA systems are used not only in industrial processes: e.g. steel making,
power generation (conventional and nuclear) and distribution, chemistry, but also in some
experimental facilities such as nuclear fusion. The size of a plant ranges from few 1000 to
several thousand to 10 thousand input/output (I/O) channels. SCADA systems used to run
on DOS, VMS, and UNIX; in recent years all SCADA vendors have moved to NT and
some also to Linux.
Software Architecture
The products are multi-tasking and are based upon a real-time database (RTDB)
located in one or more servers. Servers are responsible for data acquisition and handling
(e.g. polling controllers, alarm checking, calculations, logging and archiving) on a set of
parameters, typically those they are connected to.
FUNCTIONALITY:
1. Alarms and Event Monitoring:
A SCADA system must be able to detect, display, and log alarms and events. When
there are problems the SCADA system must notify the operators to take corrective action.
Alarms and event must be recorded so that engineers and programmers can review the
alarms to determine what caused the alarm and prevent them happening again. More
complicated expressions can be developed by creating derived parameters on which status
or limit checking is then performed. The alarms are logically handled centrally, i.e. the
information only exists in one place and all users see the same status, and multiple alarm
priority levels are supported.
DEVELOPMENT WITH THE HELP OF SCADA:
SCADA system were developed for gathering data from far and wide using poor
quality comms and providing and providing high levels of reliability and operability.
Given the rapid expansion of communication systems,(satellite, cellular, fiber, microwave
etc)and the increasing processing power available at site.
When the data gathering, integrity and validations requirements of SCADA can be
met by commonly used for IT systems, then there will be even further convergence.
SCADA system can be justified cost, but the really big payoff is to reduce the
capital investment. In many cases the applications that run at that level are becoming
more important than the user stuff. However applications like batch tracking and leak
detection are SCADA advantages.
OPERATION OF SCADA:
Supervisory control and data acquisition (SCADA) technology collects real-time
data from virtually any environment where there is a need to monitor machinery or
processes, make adjustments based on measurable conditions, measure down time, or
regulate processes to avoid costly problems. The computer-based technology was
designed to do all the things with little human involvement.
From a central reading location, a SCADA system can monitor a number of
remote sites equipped with RTUs. The RTUs measures various conditions and
parameters, including tank levels, temperature, voltage, current, volume, and flow. The
unit reports the data back to the CPU, carrying out the necessary analysis and cost
functions.
Additionally, SCADA technology personal of current or potential alarm
situations, allowing an operator to and fine tune a process. Control can be automatic or
initiated by operator commands, based on the sophistication of the individual system. The
technology is widely accepted as a reliable and efficient control system within numerous
industrial markets.
APPLICATION OF SCADA:
A typical SCADA application requires several low cost distributed RTUs,
controlled by a central station/master.
Common applications for SCADA systems typically include water and waste
treatment, petroleum and hydro carbon processing, power generation, food processing,
steel manufacturing, remote telecommunications and plant machinery maintenance.
Unlike in plant process control systems, SCADA systems typically include a
remote telecommunication link. Real-time measurements and controls at remote stations
are transferred to a CPU through the communication link. Large systems can monitor and
control 10-2000 remote sites, with each site containing as many as 2000 I/O points.
CONCLUSION:
SCADA systems are used to monitor and control a plant and equipment in
industries. The benefits one can expect from adopting a SCADA system a rich
functionality and extensive development facilities. The systems are used to mission
critical industrial processes where reliability and performance are paramount. These
systems are used to gather and analyze “real time data”.