Skin Pass Mill
Project Value: £140,000
The Skin Pass Mill (Tata Steel, Teesside) processes coils up to around 20 tonne in weight, with gauges varying from 2 to 10mm. APL supplied a complete system package using Converteam (now GE Energy) Gemdrive Micro 1 DC convertors and a GEM80 PLC. The scope of supply included :-
- New unwind and rewind drives (890A each)
- New 12 pulse main mill drive (1600A)
- New GEM80 PLC, complete with Imagem graphics and mainframe link
- New operators desk
APL were responsible for complete project management including design, manufacture, installation and commissioning.
The PLC performs all sequencing functions, coiler control functions including diameter computation, inertia calculations, loss compensation, autoslowdown, screwdowns control, serial communications with the drives for enhanced control, monitoring and diagnostic facilities, serial link to mainframe production computer, and alarms printing facilities.
The main point of interface is provided by the operator VDU, driven by GEM80 Imagem. This provides :-
- Main mimic containing relevant mill details
- Coil data entry facilities, including auto load from mainframe computer
- Current alarms details
- Alarms history
- Line run and inch permissives
- Graphical trend facilities to enable monitoring of mill performance
One of the requirements of the newly installed system was that it should be able to operate under no load conditions. This permitted the mill to rewind coils without the skin pass process, a function never previously available with the old system. This was achieved by the use of pulse generators to accurately derive coiler and mill speeds. This then enabled the PLC to perform an outer speed control, which provided a speed trim to match the mill speed with the rewind speed.
Wire Drawing Machine
Project Value: £60,000
The wire draw machine takes a basic wire coil, and draws it through a series of dies to produce a final wire size. With each die there is an associated block (physically positioned after the die) around which the wire is coiled. This block is driven by a DC convertor and motor. The higher the wire reduction, the higher the load imposed on the drive system. The final block (the ‘Rotadie’), also coils the wire vertically onto a former. In this particular system, there were a total of eight blocks, each driven by Converteam (now GE Energy) Micro 2 convertors.
Each block motor is rated at 98A DC, and operates on overspill control to achieve high top speeds. The gearbox of each block is such that the nominal top speed matches the typical reduction of each block, i.e. as the block speeds have to increase the nearer to the Rotadie (due to the reduction process), the top speed of the motor remains equivalent to maximum line speed.
As the ratio of reduction is never exactly the same for each product, a dancer control system is used to trim the speed of each block. A dancer for each block provides wire position feedback which is used directly by the drive to perform a position control by trimming the speed reference for the drive. The speed reference, including the position trim, is then cascaded to the previous drive. The whole referencing system is hardwired to ensure a fast update.
The Alspa 80/35 PLC system provides complete line control, including individual inching, line threading and striping (to empty the machine), line running and stopping. Throughout operation, the drives are monitored via a serial link to provide highly detailed alarm conditions. This link is also used to provide running data such as motor load, speed, dancer position, dancer trim output which can then be used to provide production data. A second serial link is used to communicate with the operator keypad/display unit. This provides enhanced operator facilities such as - data entry, alarm display and history, production records (e.g. lengths/weights/speeds), emergency stop and guard interlock status.
Project Value: £115,000
The coating line takes a basic steel or aluminium coil, cleans it , coats it and finally recoils it. The process runs at 90 MPM. The complete system, designed, manufactured and commissioned by APL, consisted of a total of 18 Converteam (now GE Energy) Micro 2 dc drives, a GEM80 PLC with remote I/O and operators desk with an MMI.
As can be seen from the block diagram above, the process requires a wide range of drive applications, including:
- Accumulator control - Required to position the accumulator during coil changeover. Also includes inertia compensation to ensure strip tension remains constant during speed changes.
- Tension Leveller - Provides high tension to level the strip. Can operate in tension control (current) or stretch via leveller entry and exit encoders (speed).
- Oven Catenary - Speed control with additional trim from an outer position loop. The position feedback is provided by a laser unit which monitors the strip edge position.
- Recoil - Ensures constant tension is achieved during the recoiling process. This requires the calculation of the coil diameter, coil inertia and losses. Coil data such as gauge, width, etc. is also required and is entered by the operator via the MMI unit.
The system was progressively installed and commissioned over a period of 2 years. Therefore special attention had to be given during the design stages of each installation to ensure that interface with existing equipment was successful.
Continuous process data including drive currents, line speeds, coil diameters, etc. and a comprehensive alarms facility were provided by the operator MMI unit.
Project Value: £65,000
The Ferrolite Line at Corus Packaging Plus, Trostre, produces laminated steel strip for a variety of applications. The line processes steel coils, in particular providing cleaning, laminating and recoiling facilities and runs at a speed of 80 MPM. The entry and exit sections have a maximum speed of 100 MPM to enable filling and emptying of accumualtors as determined by the process. The waxer system was added to the exit section of the line to provide the facility of coating the strip with a film of wax. This provides protection against the elements.
The system supplied by APL comprised the following:
- 4 off Eurotherm 620 AC vector controlled inverters with motor/gearbox units. These control the 4 applicator roll speeds, which in turn effectively control the application onto the strip. The drive speeds can be varied by an operator trim facility via the Siemens COROS SCADA system.
- 1 off Eurotherm 590 DC drive. This particular drive and motor/gearbox was required as the existing exit section did not have a suitable drive to provide threading once the waxer system was installed. The drive operates as a speed control for standard inching, but also has to operate via a tension loop for group threading.
- 1 off Siemens 115 PLC system. This provides overall control of the waxer system, including automatic and manual control functions. The PLC also interfaces with the existing Siemens main PLC (the existing PLC was also modified to enable this), for control and diagnostic facilities. The existing Siemens COROS SCADA system was also modified by APL to show waxer mimics, data, alarms and to give operator control functions.
Coil Inspection Line
Project Value: £45,000
The cost of modernising industrial process lines can be prohibitive. However, in this case the inspection line at Corus Steel, Ebbw Vale (site now closed) was modernised at a very low cost. This was made possible due to the following reasons -
1. The main PLC used for the line control and complex coiler calculations was the CEGELEC (now GE Energy) Gem80/35 - economical but with all the necessary speed, power and mathematical functions to perform such control.
2. The new drives provided by APL (370A CEGELEC Gemdrive Micro 2) were retrofitted on site into the existing drive cubicles. The existing power equipment - copperwork, contactors, isolators, etc, was re- used, with modifications where necessary. For example, on site copperwork facilites had to be provided.
Obviously, such a project requires much planning, especially as the removal of old equipment, installation of new equipment and commissioning of the system had to be completed within 5 days due to production requirements.
To provide operator interface with the new system, a “Communicator” unit was installed into the main desk. Data was transferred to and from this unit via a serial link.
The existing safety circuits including lockout, emergency stop and crash stop relays were also replaced by new Pilz safety relays.
Due to advance planning and a comprehensive commissioning strategy, the project was completed within the allocted 5 day period.
Project Value: £55,000
The Double Reduction Mill at Corus Steel, Ebbw Vale (site now closed) is a non-reversing cold mill which provides a double reduction process through two main mill stands with a total drive power of 10MW, and processes light gauge coils up to around 20 tonne in weight. It operated via a Ward Leonord system, but due to increased unreliability it was found necessary to update the thyristor convertors driving both the generator and motor fields. A total of 14 Converteam Micro 2 dc drives were used (varying from 13A to 70A) for this purpose, these drives being chosen due to the flexible software functions available. The scope of supply included :-
- New unwind and rewind motor and generator fields
- New entry/exit bridle top and bottom roll generator fields
- New stand 1/2 top and bottom generator and motor fields
Each drive was supplied on a pre-manufactured backplate to enable easy installation and commissioning during standard monthly maintenance periods, thereby causing no disruption to manufacturing. A time slot of only eight hours was available during each period, in which two field convertor backplates were installed and commissioned.
Special consideration to design had to be given as the generator fields were required to be reversing. This entailed the installation of high accuracy CTs for low current detection, (required during thyristor bridge changeover), along with specific software modifications for this particular application.
Installation of the drives was completed over a twelve month period.
After the installation of the field convertors, APL also supplied a new 80/35 PLC to control the entry section walking beam for the double reduction mill to replace the existing NORLOG control system.
Project Value: £120,000
The fuelling machine is basically a crane system which is used at Hartlepool power station to refuel the main reactor. It is around 60 feet above the reactor and has four drives associated with movement - long travel 1, long travel 2, cross travel and hoist. The use of two long travel drives allows the whole system to be positioned on the main tracks by adjusting the speed of one long travel with respect to the other (skew control).
The system previously used operated from a selsyn unit to provide a skew feedback, which was used to adjust the long travel speeds. However, over the distance of the normal travel of the machine, the track was not perfectly parallel, so even if the skew control operated correctly, wheel flanges would scuff the track and cause wear. Because of this problem, the main wheels had to be replaced at regular intervals. The innovative system above was devised to provide not only skew control, but also a means of controlling the displacement, thus ensuring that contact between the track and wheel flanges was eliminated.
The system consisted of fitting two distance sensors on the north and south side of the machine, which effectively monitored the flange position in relation to the track, with normal position giving a zero feedback, and +ve and -ve values for either side of this position. This meant that even if the track "meandered" over the travel range, the system would follow the track. Four new drives were also installed (Converteam Micro 2), which had the software flexibility to allow the skew and displacement control to be developed within the drives themselves.
By developing both sum and difference values within the long travel 2 drive, control of both the amount of skew and displacement is achieved. The speed of long travel 2 drive is adjusted in relation to long travel 1 drive to obtain the necessary control.
Due to the application being within the nuclear industry, hardwired protection for over-skew and overspeed had to provided to ensure safe operation.
Following the successful completion of this project, a very similar system was also installed at the Heysham power station two years later.
Project Value: £995,000
The Beam Mill at Tata Steel, Teesside manufactures beams for the construction industry, and includes a finishing end that provides facilities for the cooling and handling of the beams produced by the beam mill. The dc motors were previously driven from a 230V dc CVE supply with associated flatback panels.
The drives systems were designed, commissioned and installed by APL over a period of 2 years. Three main areas of the mill were updated as detailed below. Each supplied system followed a similar design with the drives suites being supplied with an ACCB incomer section (up to 4000A) feeding the rest of the suite via roof mounted busbars, a common auxiliaries cubicle for generation of supplies and emergency stop facilities, and the dc drives cubicles (56A to 520A full load).
As there was no means of providing a fast communication network with the existing Gem80/400 area control PLCs, a Gem80/500 PLC was supplied with each system. This provided communication with the existing PLC via FIP comms, along with a fast Profibus network to the dc drives. The new PLC also performed all necessary drives sequencing and control.
Areas updated :
- Cogging Mill - Supply and installation of 3.3KV/260V 1.6MVA transformer. Supply, design and software for drives control PLC (Converteam Gem80/500). Supply of 13 packaged dc drives (Converteam WNTC).
- Finishing End, North Route Drives - Design of 3.3KV/260V 1.7MVA transformer. Supply, design and software for drives control PLC (Converteam Gem80/500). Supply of 25 packaged dc drives (Converteam WNTC). Six drives were designed to be installed onto existing dc drives suites, and so special consideration to the design had to be given to ensure that the busbar systems matched when installed at site. Four of these drives also had to have contract specific serial communication software written within programmable software modules to enable communications to be generated with an older Gem80 PLC via ESP protocol.
- Finishing End, South Route Drives - Design of 3.3KV/260V 1.7MVA transformer. Supply, design and software for drives control PLC (Converteam Gem80/500). Supply of 24 packaged dc drives (Converteam WNTC).
Propeller Test Rig
Project Value: £120,000
The propeller test rig system was designed, manufactured and commissioned by APL in 2008.
The system had to be suitable for transporting to different test locations (in UK and Europe) and also for quick dismantling and re-installing. To enable this, all items were provided with transport wheels (including each of the 2 tonne inverter cubicles), and all connections (excluding the main inverter power) were made by industrial plug and sockets.
The system is used to test a dual propeller model in order to gain test data over varying conditions.
APL were responsible for the overall system control, and provided the following equipment:
- 2 x Vacon 690Vac, 800A 4 quadrant AC inverters. These had to be capable of regenerating as the main propellers were situated within test wind tunnels and therefore were susceptible to windmilling effects. They also had to be capable of operating the two specially designed and manufactured liquid cooled motors to speeds of 7000 rpm (360Hz). Optimal fluxing software was used to ensure the motors did not overheat due to high currents.
- 1 x Rockwell Compact-Logix main system PLC to provide overall control, referencing and various communication links to enable control, data collection and diagnostics, these being -
- Devicenet to the two inverters.
- Ethernet to the model cooling system.
- Ethernet to the operators Scada system.
- Ethernet to a remote PC.
- Operators desk with hardwired control and indication functions, along with a PC Scada (Rockwell Factory Talk) system with the following functions -
- System set up.
- System mimic displays.
- System and model information displays, eg temperatures, pressures, currents, speeds, etc.
- Trend functions to plot system and model variables.
- Alarms and diagnostics facilities.
- Printing facilities for trends and alarms.
Cable Armouring Machine
Project Value: £120,000
The armouring machine supplied to AEI Cables provides protective armouring for multicore cabling.
The complete electrical system supplied by APL consisted of 2 DC drives complete with DC motors, and an operators desk.
An additional auxiliary control cubicle was also provided for:
- Cooling oil pump control
- PIV control
- Spray control
The control for the armouring machine is based around the two main DC drives. The main drive operates as a speed control, which determines the overall machine speed via an operators set point. A mechanical line shaft drives the cable binder and main carriages which perform the main armouring process, along with an output capstan. PIVs are used to give control between these units.
From the output capstan, the tension is controlled by the output caterpillar. This drive follows the speed of the main drive, but tension is controlled by an operators potentiometer which acts as a current limit. An additional lead is added to the speed reference so that the speed control operates in saturation, the tension being limited by the operators tension potentiometer. This system ensures that if a cable break occurs, the motor will not overspeed but will hold the speed as defined by the main reference with the added speed lead.
The use of modern digital drives (in this case CEGELEC (now GE Energy) Gemdrive Micro 2) enables much hardware sequencing and control previously required on such projects to be dispensed with. For example, the output caterpillar operates as a tension control drive during line run but also requires speed control functions for inching. Also, automatic change over from a stall reference to operators set tension is selected within the drive software. The main drive similarly performs interlock functions, for example speed dependent functions that control some of the auxiliary AC drives, and brake control.
Wind Power Simulation Test Rig
Project Value: £410,000
The system was supplied to Siemens Wind Power at Keele University and is used to test newly developed wind generator inverters.
Common to both systems was the cooling system. This was effectively 2 separate systems, with 100KW cooling for the static system and 20KW for the dynamic system. Each had its own remote I/O subrack controlled from the main PLC via Ethernet/Fibre optics. Fibre optics was chosen to ensure noise free operation as the cables are run in the trench with the main power cables.
The static test rig enables inverter testing at high currents (to 4000A) at fixed frequencies. APL provided the following for this test rig:
- 4000A Incomer design.
- PWM Filter panel.
- Coolant system.
- PLC system supply.
- PLC and touchscreen software. Installation and commissioning.
The dynamic test rig enables testing at variable frequencies via an MG set, built from an induction motor and a permanent magnet motor. These motors can be reversed to simulate either type of generator when testing. The MG set is driven by a Siemens 720A G130 convertor. A separate grid fault panel was also supplied (containing reactors and shorting contactors) to check the operation of the test unit under fault conditions.
APL provided the following for this test rig -
- 800A Incomer design.
- Coolant system.
- PLC system supply.
- PLC and touchscreen software.
- 40ft industrial container (Lloyds certified), with:
- MG set with bedplate.
- Siemens converter panel.
- Grid fault panel.
- Remote I/O panel.
- All installation and commissioning.
Four years later, an additional over-voltage test facility was added by APL to the dynamic test rig at a cost of £145,000. This was a new system complete with power equipment and a PLC, and enabled over-voltage pulses to be applied to the unit being tested.
Roll Grinding Machine
Project Value: £180,000
The Walrich 5 and Farrel 60 are two virtually identical roll grinding machines at Tata Steel, Trostre, and are used to re-grind mill rolls which are worn or damaged due to use. Each machine has to accurately grind the rolls to a tolerance of around 2 microns, with options to grind the rolls flat, or cambered. Depending on the amount of damage to the rolls, multiple grinding passes are made (from around 5 up to 30) to remove roll damage and blemishes.
To keep the cost of the project as low as possible, the existing control suites were re-used. All old DC drives, axis drive racks, and PLCs were removed and replaced with Rockwell systems. Each system was installed, cabled, tested and commissioned in less than 2 weeks.
To ensure that the accuracy required was achieved, all of the DC drives and axis drives were controlled over Ethernet.
The emergency stop system and machine guarding were updated by the use of programmable Pilz safety relays due to the complexity of operation required.
The main operator desk was also modified to allow the installation of a remote I/O station and a PC system with an Ifix Scada package installed.
The Ifix provided all the necessary control and diagnostic functions required to operate the machines successfully. These functions included:
- Operator “recipe” selections to enable quick set up of roll grinding.
- Manual functions to modify parameters if required.
- Mimics with grinding information and machine data.
- Complete diagnostic facilities, with alarms system and alarm history.