Industrial Control Systems
Case Studies using SCADA, PLCs and Distributed Control Systems
Control of 400kV Grid Switchgear
JK Controls Ltd designed
industrial control systems for a CCGT power station in the UK, using SCADA systems
to operate remote circuit breakers
over a 2km fibre optic link. The
communications used dual pairs of single mode optical cores to provide secure
data transmission between the local and remote areas.
Mitsubishi PLCs were used for
gathering the plant information and for commanding the switchgear.
A PC running Citect SCADA provided the operator interface in the
control room. The system was also
integrated into the control room mimic display panels for duplicate indication
of the switch states.
A severe installation
constraint was imposed by the section of the Grid System only being available
for maintenance for 2 days every 18 months. The system was to replaced
existing obsolete equipment, which was still operational. JK Controls therefore designed and manufactured custom interface
cards with plug and socket connectors which were compatible with the
connectors of the obsolete equipment. Furthermore
the legacy equipment operated at 50v dc positive earth, so the bespoke
interface cards incorporate level shifting and optical isolation circuitry to
match the industry standard 24v dc technology of the PLC. The output contacts are all duplicated for security.
The process control system
built and thoroughly tested prior to change-over from the old system, enabling
completion in the 2 day outage period allowed.
From enquiry to commissioning the task was completed in only 3 months.
Power station relocation and DCS
client is removing a power station from UK for rebuild at a steel works in the
Far East. The blast furnace turbine driven air blowers are from a
different site. JK Controls is engaged in re-equipping all of the
instrumentation and control services. The disparate collection of second
user plant presents a unique set of problems in establishing successful
control. For example, the boilers are of different size and the steam
conditions required by the several turbines differ considerable.
Unreliable grid supplies puts special demands on the controls to be able to
sustain essential air and electricity supplies from the steam driven plant in
the event of loss of external supplies. Economic and environmental constraints
demand that the blast furnace waste gas is optimally consumed within the power
station boilers. JK Controls is sourcing and coding a new distributed
control system (DCS) and mimic screens, sourcing
new and second user instrumentation, retrofitting obsolete equipment, designing all systems and control room,
commissioning the final installations and training staff.
Boiler - Generator control
Our client has successfully
retrofitted a complete control system to 2 x 500MW boiler/turbine units, using
modern distributed control system (DCS) technology. Our personnel were engaged to provide expert
assistance with advice, design effort and commissioning of the control
structure. The operational needs of the national grid system and the
commercial constraints which now pertain to power plant operation, set onerous
demands upon load and frequency regulation. We custom designed the boiler and
turbine controls and built a computer simulation of the appropriate sections
of plant. The controls were then optimized off line using the model to
achieve near optimum control prior to committing to the plant for final
commissioning. The plant is now providing close control of load and
frequency response together with on time run up to target load, as required by
Crash Test Rig
client (TRL Ltd) operates a range of transport research and test facilities.
A new facility has been built for testing components such as child seats,
wheel chair securing attachments, F1 racing car nose cones, etc.
JK Controls Ltd. have designed, built and commissioned the controls for
operating the test and recording results.
trolley carries the sample under test, which is projected along a track by
strong rubber cords using a patented design.
The trolley is then brought to rest by means of a rapid deceleration
apparatus or by impact with a solid steel wall, dependent upon the type of test
being carried out.
Controls supplied a PLC and SCADA based control system to handle the test
set-up, test sequencing, safety interlocking, data gathering and post-test
recording of results.
The system uses Microsoft Access for data set-up and results history,
Citect SCADA for operator interaction, and Mitsubishi Q series PLC for data I/O
and control. The
screen appearances of the software systems are customised to give a consistent
operator is able to type in a desired impact speed, the number of cords and the
diameter of the cords, as well as many other menu based test set-up
The trolley is weighed and the point of initial impact registered.
The trolley is winched back and the system then carries out a calibration
sequence using force and position measurements with calculations to determine the desired release
point for the trolley that will enable the final speed at impact to be within 1%
of the desired value.
At the onset of impact a high speed measuring phase is started which
gathers depth of impact data, checks its validity, stores the data and records
the greatest depth of impact prior to rebound.
Position measurement was a challenge due
to the rapid movement, deceleration and non-contact requirement of the
application. We researched several methods of measurement and carried out
extensive tests, finally settling upon a Sick-Stegmann laser system with rapid
enables measurement of impact depth to within 2mm and location of the trolley
over the full track length of 22 meters.
completion of the test further data is recorded regarding maximum acceleration
prior to impact and measured impact speed.
The stored energy at release and the energy actually imparted at impact
are calculated to determine the efficiency and hence refine the calibration of
Controls built the control panels and custom designed electronic systems for
speed measurement and calibration.
River Level Control systems within Flood Defence
JK Controls Ltd have carried out specialist
control systems projects for the National Rivers Authority and the Environment
Agency, undertaking design, procurement, building, installation, commissioning
and documentation of measurement and control schemes for weirs, gates,
penstocks, pumps, screens, water intakes etc.
Where many individual installations on a river
have been designed and built by an array of different contracting
organisations, there will inevitably be a diversity of designs and methods
amongst them. JK Controls has taken the best features and eliminated the
worst to improve the overall operation and reliability of the installations.
- In the absence of detailed information for
existing installations, analysis of the river level control software and
hardware has been undertaken, enabling reverse engineering and production
of drawings and manuals for operation and maintenance function.
Where existing control schemes have been of poor design we have analysed
the problems, written reports, re-designed and improved the systems.
- In order to thoroughly verify automatic
control systems under all operational and fault conditions physical models
have been built, thus enabling creation of control schemes that are fully
working and tested prior to fitting at site and so reducing commissioning
set up using model penstock
|| On site
commissioning of river level controls
- Apart from the plant control there is also
the neglected issue of operator "friendliness". Care is
taken to ensure that HMI displays, messages and other operator
interactions are managed in an ergonomic way to minimize confusion.
- JK Controls Ltd also carries out routine and
breakdown maintenance of the controls to achieve high availability of the
- We can supply, install and maintain
Contact Information: e-mail to firstname.lastname@example.org,
or telephone +44 1732 522353
Address: JK Controls Ltd, The Barn, 65 High Street, East Malling, Kent, ME19
6AJ. Reg. No.
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