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Project Title: Automation & Control
Student's Name: Viral Mandaviya
Programme: B.Tech Mechanical & Automation Engineering
Year: 2006-2010
Semester: 7th
Faculty Guide: D. K Sharma
industry Guide: Franklin Stephenson
ABSTRACT
The demands made on the surface quality and thickness of steel strip have increased in recent years. At the same time, operators have had to concentrate on maintaining high annual production rates. To balance these needs, plants have to be equipped with advanced electrical systems featuring dedicated control functions.
This is a study made on the general automation and control system generally used in major Steel Industries of the world. This study deals only with the products and services provided by ABB Ltd. This Study includes the general description on Automation & Control System of Steel Industry, Drives, AC800 Power Electronics Controller, Communication Protocols & Case Study on Coil Car Pushing.
When procuring electrical equipment for a plant, consideration needs to be given not only to the first-time cost of the equipment but also to the total cost over its lifetime. This has to take into account factors such as efficiency, energy consumption, spare parts and maintenance. The industry's preference in the past for adjustable speed DC drives, which easily achieve a good torque and speed response, is giving way to a trend towards AC drives. This has come about as a result of modern electronic converters offering the same speed accuracy and fast torque response,
but with the added plus that the AC motors allow a major cost saving due to their simpler construction and high reliability, even in harsh environments, and easier maintenance.
It is not possible to define a unique control strategy for a continuous processing line that will take account of all the different drive combinations in the various line configurations; this is particularly true in the case of the process section. Nevertheless, it can be done for some of the motor drives.
This arrangement, known as indirect tension control, ensures that the required strip speed and tension are maintained. Another words, a bridle not assigned the function of a speed master acts as an indirect tension-controlled drive. I could successfully understand the whole system of automation and control in a metal industry. I understood the products and services provided by ABB Ltd and I was even fortunate to learn the manufacturing, assembly & testing procedures of those products.
INTRODUCTION
The demands made on the surface quality and thickness of steel strip have increased in recent years. At the same time, operators have had to concentrate on maintaining high annual production rates. To balance these needs, plants have to be equipped with advanced electrical systems featuring dedicated control functions.
This is a study made on the general automation and control system generally used in major Steel Industries of the world, amongst them is ABB Ltd.
ENTRY TO EXIT AUTONATION WITH ADVANCED ELECTRICAL SYSTEM IN
COLD ROLLING AREA
New developments in AC drive technology, including Direct Torque Control,are at the heart of advanced electrical systems developed by ABB for stainless steel treatment lines. Among the system features are operator stations for automated plant control and efficient management of the production data. Powerful software functions not only enable steel producers to control the quantity of produced material more precisely but also provide valuable information about the quality of the finished steel strip.
Adjustable-speed AC drives featuring advanced DTC technology and flexible control systems are destined to make a significant contribution to process line developments in the metallurgical industry Steel producers benefit from the use of such powerful tools not only by being able to control more precisely the quantity of produced material but also due to the important information they provide about the quality of the finished strip.
This study features intoducion to automation, Standard Drive(ACS800), System Drive(ACS800), Motion Control Drive(ACS M1),Power Electronics Controller(AC800 PEC), Communication Protocols, Compact Control Builder and a Case Study on Coil Car Control.
INTRODUCTION TO METAL
INDUSTRY
What is Metal
Greek Metallon, a word of unknown origin, has a range of meanings, including 'mine' (the original sense) and 'mineral' as well as 'metal.' These were carried over into Latin Metallum, but by the time the word reached English, via Old French metal, 'metal' was all that was left. Mettle is a variant spelling of metal, used to distinguish its metaphorical senses. Closely related to medal, which etymologically means 'something made of metal.'
Metal : a substance that is usually shiny, a good conductor of heat and electricity, and can be
made into wire, or hammered into sheets. Gold, silver, iron, copper, lead, tin
or aluminum are metals" . All metals can be classified as either Ferrous or Nonferrous.
How metals are manufactured
Industries in the Primary Metal Manufacturing subsector smelt and/or refine ferrous and nonferrous metals from ore,or scrap, using electrometallurgical and other process metallurgical techniques. Establishments in this subsector also manufacture metal alloys and superalloys by introducing other chemical elements to pure metals. The output of smelting and refining, usually in ingot form, is used in rolling, drawing, and extruding operations to make sheet, strip, bar, rod, or wire, and in molten form to make castings and other basic metal products.
Non-Ferrous Metals
These are metals which do not contain any iron. They are not magnetic and are usually more resistant to corrosion than ferrous metals. Example aluminium, copper, lead. zinc and tin.
Ferrous Metals
These are metals which contain iron. They may have small amounts of other metals or other elements added, to give the required properties.
Rolling Mill
Rolling: A process of working on metals to flatten or spread ,by passing them through rotating rolls.
Mill: A machine for grinding or crushing
Rolling Mill: Machine where metal is rolled in to sheets and bars.
Rolling Mills Classification
ROLLING MILL
¢ FLAT MILL
o HOT ROLLING
¦ ROUGHING MILL
¦ FINISHING MILL
¦ DOWNCOILER o COLD ROLLING
¦ 20Hi MILL
¦ 6Hi MILL
¦ 4Hi MILL
¦ 2Hi MILL
¢ PROFILE MILL
o HOT ROLLING and COLD ROLLING
A
Rolling is a fabricating process in which the metal, plastic, paper, glass, etc. is passed through a pair (or pairs) of rolls. There are two types of rolling process, flat and profile rolling. In flat rolling the final shape of the product is either classed as sheet (typically thickness less than 3 mm, also called "strip") or plate (typically thickness more than 3 mm). In profile rolling the final product may be a round rod or other shaped bar, such as a structural section (beam, channel, joist etc). Rolling is also classified according to the temperature
Profile rolling for a cone
of the metal rolled. If the temperature of the metal is above its recrystallization temperature, then the process is termed as
hot rolling. If the temperature of the metal is below its recrystallization temperature, the process is termed as cold rolling. Another process also termed as 'hot bending' is induction bending, whereby the section is heated in small sections and dragged into a required radius.
Heavy plates tend to be formed using a press process, which is termed forming, rather than rolling.
The process involved in a steel plant are mining of ore, steel making, slab casting, reheating, hot rolling, cold rolling, strip processing, saleable product.
Hot rolling
Hot rolling is a hot working metalworking process where large pieces of metal, such as slabs or billets, are heated above their recrystallization temperature and then deformed between rollers to form thinner cross sections. Hot rolling produces thinner cross sections than cold rolling processes with the same number of stages. Hot rolling, due to recrystallization, will reduce the average grain size of a metal while maintaining an equiaxed microstructure where as cold rolling will produce a hardened microstructure.
Hot Rolling Process
A slab or billet is passed or deformed between a set of work rolls and the temperature of the metal is generally above its recrystallization temperature, as opposed to cold rolling, which takes place below this temperature. Hot rolling permits large deformations of the metal to be achieved with a low number of rolling cycles. As the rolling process breaks up the grains, they recrystallize maintaining an equiaxed structure and preventing the metal from hardening. Hot rolled material typically does not require annealing and the high temperature will prevent residual stress from accumulating in the material resulting better dimensional stability than cold worked materials.
Hot rolling is primarily concerned with manipulating material shape and geometry rather than mechanical properties. This is achieved by heating a component or material to its upper critical temperature and then applying controlled load which forms the material to a desired specification or size.
Hot Rolling Applications
Hot rolling is used mainly to produce sheet metal or simple cross sections such as rail road bars from billets.
Mechanical properties of the material in its final 'as-rolled' form are a function of:
¢ material chemistry,
¢ reheat temperature,
¢ rate of temperature decrease during deformation,
¢ rate of deformation,
¢ heat of deformation,
¢ total reduction,
¢ recovery time,
¢ recrystallisation time, and
¢ subsequent rate of cooling after deformation.
Types of hot rolling mill
Prior to continuous casting technology, ingots were rolled to approximately 200 millimetres (7.9 in) thick in a slab or bloom mill. Blooms have a nominal square cross section, whereas slabs are rectangular in cross section.Slabs are the feed material for hot strip mills or plate mills and blooms are rolled to billets in a billet mill or large sections in a structural mill.
The output from a strip mill is coiled and, subsequently, used as the feed for a cold rolling mill or used directly by fabricators. Billets, for re-rolling, are subsequently rolled in either a merchant, bar or rod mill.
Merchant or bar mills produce a variety of shaped products such as angles, channels, beams, rounds (long or coiled) and hexagons. Rounds less than 16 millimetres (0.63 in) in diameter are more efficiently rolled from billet in a rod mill.
COLD ROLLING
Cold rolling is a metalworking process in which metal is deformed by passing it through rollers at a temperature below its recrystallization temperature. Cold rolling increases the yield strength and hardness of a metal by introducing defects into the metal's crystal structure. These defects prevent further slip and can reduce the grain size of the metal, resulting in Hall-Petch hardening.
Cold rolling is most often used to decrease the thickness of plate and sheet metal.
HISTORY
Dates back to 1859. Initially cold rolling developed in the area of profile mills. Later with the development of wider mills,cold flat rolling developed to what it is to-day. Purpose of cold rolling was more to achieve mechanical properties than required end thickness. To-day's cold rolling produces tailor made products to suit individual end product requirement.
Physical metallurgy of cold rolling
Cold rolling is a method of cold working a metal. When a metal is cold worked, microscopic defects are nucleated throughout the deformed area. These defects can be either point defects (a vacancy on the crystal lattice) or a line defect (an extra half plane of atoms jammed in a crystal). As defects accumulate through deformation, it becomes increasingly more difficult for slip, or the movement of defects, to occur. This results in a hardening of the metal.
If enough grains split apart, a grain may split into two or more grains in order to minimize the strain energy of the system. When large grains split into smaller grains, the alloy hardens as a result of the Hall-Petch relationship. If cold work is continued, the hardened metal may fracture.
During cold rolling, metal absorbs a great deal of energy. Some of this energy is used to nucleate and move defects (and subsequently deform the metal). The remainder of the energy is released as heat.
While cold rolling increases the hardness and strength of a metal, it also results in a large decrease in ductility. Thus metals strengthened by cold rolling are more sensitive to the presence of cracks and are prone to brittle fracture.
A metal that has been hardened by cold rolling can be softened by annealing. Annealing will relieve stresses, allow grain growth, and restore the original properties of the alloy. Ductility is also restored by annealing. Thus, after annealing, the metal may be further cold rolled without fracturing.
Degree of cold work
Cold rolled metal is given a rating based on the degree it was cold worked. "Skin-rolled" metal undergoes the least rolling, being compressed only 0.5-1% to harden the surface of the metal and make it more easily workable for later processes. Higher ratings are "quarter hard," "half hard" and "full hard"; in the last of these, the thickness of the metal is reduced by 50%.
Cold rolling is a common manufacturing process. It is often used to form sheet metal. Beverage cans are closed by rolling, and steel food cans are strengthened by rolling ribs into their sides. Rolling mills are commonly used to precisely reduce the thickness of strip and sheet metals.
Types Of Cold Rolling Mill
¢ Reversible Mill
o 20Hi o 6Hi o 4Hi
o 2Hi
¢ Non-reversible Mill
o Tandem Mill o Skin Pass Mill
COMPONENTS
Pay-off Reel
The incoming coil which is the raw-material to be processed is loaded.This is a rotating mandrel which may be electrically or hydraulically driven. Tension Reels
Where the strip after reduction in each pass is wound.Tension reels are electrically driven from Drives and maintain a constant tension in the strip for proper winding. Mill Stand
Contains set of rotating rolls where reduction takes place.These rolls are rotated at constant speed and hydraulic pressure to get the desired thickness.
¢ Consists of a hydraulic mandrel with segmented construction.
¢ After coil loading,mandrel is expanded to hold the coil tight.
¢ Is driven by electric motors, either AC or DC.
¢ Is required to provide a constant preset tension throughout the coil.
Screwdown (Hydraulic or Electric)
To impart the necessary pressure on the rolls which work on the strip.
rolling.
¢ There is no scale formation in case of cold rolling,which results in loss of metal as scale.
¢ Hot rolling results in decarburization as strip is heated and rolled at high temperatures.This deteriorates the surface qualities of the strip.
¢ Cold rolling and subsequent annealing develops superior grain structure.
¢ Cold rolling improves permeability,is good for transformer steels.
PROCESSING LINE
Hot rolled coils needs to be surface cleaned before they can be taken for cold rolling. Cold Rolled metal will not have the necessary chemical and surface properties desired for various end products for which they will be used. Processing lines is the generic name for a machine which runs the rolled metal through a process which imparts the necessary surface or chemical qualities. Depending on the type of process,a processing line may be positioned ahead or after cold rolling. Main processes are:
¢ Annealing
¢ Pickling
¢ Galvanizing
¢ Tinning
¢ Electrolytic cleaning
¢ Tension levelling cum inspection lines
¢ Cut to length/ Slitting lines
¢ Some times annealing is carried out as a separate process through Batch Annealing Furnaces.
Challenges In Rolling Mill
¢ Controlling 40 tons of rolls to a positioning accuracy of 1 urn with a roll force of up to 30 MN in a roll gap of a rolling mill
¢ Controlling strip thickness of 2 x 6 um with an accuracy of < ± 0,5 um with about 15
close tight integrated control loops with a scan time between 2 and 20 msec
¢ Controlling the tension in a Cold Rolling Mill (CRM) or Processing Line (PCL) to a static accuracy of ± 1 % and dynamic to ± 2 %
¢ Coordination of 6 (CRM) to 200 (PCL) drives in a speed range of 400 ... 2000 m/min with acceleration of 100 ... 400 m/min/sec
Overview or AUTOMATION & CONTROL systems
One of the most important parts of an integrated steelworks is the cold rolling area, where the oils from the hot rolling mill are processed into steel strip.This area can be divided into two main sections :
¢ Cold rolling mills for reducing the strip thickness
¢ Plants for the treatment of the structure/surface of the material and for changing the strip dimensions (Table 1)
The electrical equipment installed for the strip treatment plant has a large influence on the quality of the finished products. For example, the line control system has to ensure very precise movement of the strip.A standstill in the process section or uncontrolled strip tension can easily cause irreversible damage to the material or loss of production.
Table 1
Plants determining the structure and surface of the material
Surface Surface treatment/ Strip dimensions
improvement structural change
¢ Electrolytic ¢ Pickling lines ¢ Slitting lines tin/chrome lines ¢ Continuous annealing ¢ Shearing lines
¢ Electrolytic cleaning lines ¢ Recoiling lines
¢ Galvanizing and ¢ Combined annealing aluminizing lines
¢ Coating lines ¢ Electrolytic strip Degreasing
Main processing lines
Strip processing lines alter the characteristics,appearance and/or dimensions of flat-rolled products. Typical examples are the galvanizing line, which coats the steel with a layer of corrosion-resistant zinc, the colour coating line, which applies a layer of paint, and the slitting line, which cuts wide coils into narrow strips. Except for those lines with a shearing section at the exit end, most coil processing lines can be described as continuous coil-to-coil operations. This means that coils of metal are brought to the line entry, uncoiled, fed continuously throughout the treatment process, and recoiled at the exit.
Continuous operating lines
To ensure that the quality goals are achieved, the process sections have to operate at constant speed and the process has to be supervised from beginning to end. After preparation of the coil, eg by removing any damaged outer wraps, the strip is fed into the line. One of the first operations to be performed is the welding of the incoming coil to the tail end of the coil being processed. This is a prerequisite for continuous operation, and requires a strip storage device known as the entry looper. The entry looper, in effect a buffer between the entry and the process area, stores enough strip to keep the processing section operating during the welding. As soon as the looper has emptied, the entry section accelerates to a preselected overspeed to provide more strip to
refill it.
The main functions of the exit section are strip rewinding and coil discharging. These are made possible by another looper, which stores the strip coming from the processing section. Also, the exit section is capable of working at overspeed to compensate for the excess strip stored in the exit looper during stops in this section.
Annealing and pickling line
The annealing and pickling line (APL) is one of the plants requiring a constant material processing time. To remove the hardness caused by rolling, the strip is first run through the annealing section of the APL. During the annealing process the lattice of the steel is stress-relieved and its structure rearranged. Annealing can be performed in a continuous process in which the strip is passed through a furnace with different heating zones that raise it to an exactly defined temperature and afterwards through cooling zones that gradually cool it down to its exit temperature of about 80 °C (higher temperatures cause the line to be stopped to prevent possible damage to mechanical equipment further along). The temperatures in the heating zones are varied according to the type of steel being treated and the strip gauge and width. After being annealed the strip is passed through the pickling section to give the material a clean, bright surface. This section consists of tanks containing electrolytic, electrochemical and mixed acid solutions. Table 2 gives details, including the running speeds and annealing data, of a new APL installed recently by ABB at Baoyong Special Steel in Ningbo, China . Drive control strategy It is not possible to define a unique control strategy for a continuous processing line that will take account of all the different drive combinations in the various line configurations; this is particularly true in the case of the process section. Nevertheless, it can be done for some of the motor drives.
Normally, it is necessary to isolate the strip tensions in the various sections from each other in order to stop one section from influencing another. This is accomplished by means of speed-controlled bridle rolls. Each section has a master bridle which determines the reference speed; a speed pilot in the entry and exit sections controls the overspeed for the looper operation during stops (eg, for coil welding and finishing operations). When these operations have been completed the speed is adapted again to the process. Normally, there is one bridle operating in underspeed mode (feedbackward regulation) and another in overspeed mode (feedforward regulation), in each case referred to the master bridle of the process. This arrangement, known as indirect tension control, ensures that the required strip speed and tension are maintained. In other words, a bridle not assigned the function of a speed master acts as an indirect tension-controlled drive. Very precise control of the strip tension is necessary to avoid strip breakage in critical areas. Direct tension control, with load cells mounted directly on the rolls , guarantees this.
Table 2
Specification of the new annealing and pickling line at Baoyong Special Steel in Ningbo, China
Product data
Strip material Hot and cold stainless steel
Strip thickness Strip width Coil weight
(AISI300-400) 0.3 mm - 5.0 mm 650 mm - 1350 mm max 31 t
Running characteristics of line
Threading speed Entry/exit speed Process speed
25 m/min 90 m/min 60 m/min
Entry/process/exit acc and dec
Normal acceleration Normal deceleration Fast stoppage
+ 0.13 m/s2
- 0.13 m/s2
- 0.26 m/s2
Annealing temperatures
HR 300 CR 300 CR 400
1130 °C 1090 °C
840 °C
Usually, the speed control of a master bridle is based on load sharing between the two drives of the bridle. The advantage of this configuration over the solution with one drive as the speed master and the other speed-controlled is that the stability is better during acceleration and deceleration and differences in the roll diameter are compensated for at constant speed. Indirect tension control with compensation of acceleration and losses is normally used for the coiler and looper. Thus, in the entry and exit section only one bridle is designated the speed master. If there is a side trimmer in the exit section it may have (with respect to the strip direction) one bridle before and one after the side trimmer, the latter acting as master so as to ensure constant speed at the side trimmer.
There is no particular rule for the process section. In general, the speed master should be behind the most critical part (eg, the furnace). If the line has only one process, the speed master will be next to the exit of the process. If there is a stretch leveler in the section, the leveler itself should be the master.
Electrical solutions
When procuring electrical equipment for a plant, consideration needs to be given not only to the first-time cost of the equipment but also to the total cost over its lifetime. This has to take into account factors such as efficiency, energy consumption, spare parts and maintenance. The industry's preference in the past for adjustable speed DC drives, which easily achieve a good torque and speed response, is giving way to a trend towards AC drives. This has come about as a result of modern electronic converters offering the same speed accuracy and fast torque response, but with the added plus that the AC motors allow a major cost saving due to their simpler construction and high reliability, even in harsh environments, and easier maintenance.
Direct torque control
Direct Torque Control (DTC) [1, 2, 3] is the motor control platform launched by ABB in 1994 as the universal solution for LV drive applications and recently adapted for MV applications. This technology is also used to control the induction motors delivered to the new annealing and pickling line of Baoyong Special Steel in Ningbo, China.
Unlike traditional vector control, in which the parameters affecting the voltage and frequency (eg, the motor current and flux) are measured indirectly and a pulse encoder has to constantly provide new data to obtain a real degree of accuracy, DTC allows fast and flexible control of the
machine without encoder feedback. Also, the variables used in flux vector control are controlled by a modulator, which delays the responsiveness of the motor to changes in torque and speed. DTC onthe other hand uses advanced motor theory to calculate the torque directly without the need for a modulator; the control variables are the stator flux and the motor torque. When DTC open-loop drives are installed, high dynamic performance (speed accuracy and torque control) is possible in many cases without having to use a tachometer. Where a higher accuracy is required, closed-loop DTC drives are employed, but the feedback device may be less accurate and therefore cheaper than the one used in traditional flux vector drives as the speed error and not the rotor position is known by the drive. In processing lines such as the APL described, the main motors used to transport material (in the bridles, loopers, uncoilers, coilers) are fitted with pulse generators. The control variables in DTC are:
¢ Stator flux
¢ Torque, calculated on the basis of the flux and stator current
¢ Comparison of the flux amplitude and torque deviation with given references;
the information this provides is sufficient to determine the optimum voltage vector at each instant The high precision of the mathematical motor model makes speed feedback unnecessary. Combining high-speed signal processing with the advanced mathematical model has produced a 25 us high-performance control loop that ensures accurate torque control and low oscillation levels. The resulting very fast torque response makes the DTC AC drive twice as fast as flux vector AC drives and at least ten times faster than open-loop AC drives with scalar control. Other benefits in the torque control area include very precise torque control at low speeds, even down to zero, and full torque at zero speed. Measurements of shaft torque (with a torque ramp from 100% to -100 % at zero speed) for different drive controls are shown in . With DTC the dynamic speed accuracy is at least eight times better than with open-loop AC drives, and static speed control accuracy is twice as good as with the existing general-purpose AC drives .
Automation systems
Modern automation systems based on an open system architecture provide userfriendly, reliable tools that support the operator in his daily work. Such systems feature a combination of field controls and higher-level information that makes it easy to interchange data between the Open Control System (OCS) and the Manufacturing Execution System (MES) . By combining these concepts, a plant automation system evolves with capabilities that extend from single motor control to overall plant control.
OCS operator stations
Advant OCS operator stations have direct access to a database in which all the data related to the processing line is stored. BLocated at the entry and exit pulpits of the line, the stations manage alarm reports and information arriving from each section, allowing the status of the plant to be kept under control. For example, the general starting conditions, motor torque and motor speed can be viewed and preset from these stations.
Strip tracking is one of the main functions provided by Advant OCSl. It as assists the operator with routine work by keeping track of the coil welding so that the position of the strip inside the line and the amount of coil threaded in the entry section and rewound at the exit are always
known.
Standard ABB solution
ABB Advant® Open Control System
With its Advant® Open Control
System (OCS), ABB offers a standard, state-of-the-art platform
with open system architecture for the
automation of industrial processes.
The system is characterized throughout by an object-oriented and distributed structure, high-performance operator stations, very high availability and ease of maintenance. All process and operator stations are linked by a
systembus.The process control
stations communicate with I/O units
by means of field buses. Every stage
in the industrial process can be controlled and monitored from each
of the process operator stations.
Programmable logic controllers manage the exchange of signals between the different process sections. The current standard ABB solution for a strip processing line consists of two PLCs (AC450RMC) dedicated to applications in the metallurgical sector. A wide choice of standardized functions and ready-made software modules makes it easy to find reliable solutions that meet customers' needs.
The first multi-CPU AC450 controls the entry section, the tracking and the presetting functions, while the second PLC interfaces with the process and exit sections.To relieve the CPU load of the PLCs some functions are implemented on the motor drives; these incorporate the majority of the application software for motor control. The large drive systems are, in fact, linked through a fast, dedicated fieldbus(AF100) via a control unit called the Application Controller (APC). Softwarerunning on the APC includes modules for speed control, current control and tensioncontrol. Remote I/O devices communicate through the AF100 with the overriding
control CPU.
The standard overall control system function covers the generation of all sequences,velocity and acceleration references for the drives, and the signals for starting and stopping the line. Application specific modifications are made according to the project requirements.
OCS Alarm
Operator Station reports
MES Operator Station
OCS PC server
MES PC server
Ethernet comm. bus
AC 450 AC 450
AF 100
Remote I/Os Drives Remote I/Os Drives
Automation layout with two multi-CPU PLCs in control of the whole line. From the control desk it is possible
to view all the operations taking place in the line.
Manufacturing Execution System
Quality control depends not only on accurate control of the technological parameters of the strip but also on overall control of the production process. The necessary coordination is achieved by means of Manufacturing Execution System (MES) functions, being divided into operator functions and process functions.
Operator functions
These functions are as follows:
¢ Order management, giving the list of coils to be worked and detailing for each coil its dimensional data, main characteristics (coil code, steel grade identification for furnace and pickling, customer code) and required final characteristics.
¢ Line preset management , comprising a set of data used to set the line up before starting production; preparations for all the electrical and mechanical devices are based on the order data. Coil data given by the order management and line preset functions assigned to the coil constitute the preset data sent to the OCS for correct coil processing.
Coil reporting , with displays and print-outs of data on worked coils. The main displays are the quality product report (thickness, flatness, elongation data) and the technological product report (furnace, pickling, thickness, flatness, elongation distribution data for the process technology engineer).
Production reporting, showing the number of coils produced and the work shifts in the plant (production reports can be displayed on a shift, daily and monthly basis). Reporting of the plant time distribution (how long the plant has been in operation and how long at standstill) and the pickling consumption is also possible.
¢ Maintenance reporting, showing the actual operating time of the mechanical and electrical equipment.
Process functions
These functions are automatically activated by the system whenever a message is received or something occurs in the plant.
¢ Material tracking, allowing monitoring of the position of the coil in each section of the line.
¢ Data acquisition, for collecting information from the OCS about the uncoiler and recoiler, tension and process sections, as well as for archiving in the system database.
APL automation systems normally make use of mathematical models that control the processing area with high precision and have a direct effect on the overall strip quality. In the case of the furnace, for example, the mathematical model uses the line speed, type of steel, strip width and thickness as information when converting the annealing curve characteristics into working parameters. A model may also be provided for the pickling area, for example to precisely control the acid dosing needed to obtain a clean, bright surface.
DRIVES
In electrical engineering, a drive is an electronic device to provide power to a motor or servo. A Drive (motor controller) is a device or group of devices that serves to govern in some predetermined manner the performance of an electric motor. A motor controller might include a manual or automatic means for starting and stopping the motor, selecting forward or reverse rotation, selecting and regulating the speed, regulating or limiting the torque, and protecting against overloads and faults. There are in general three types of dirves : Standard Control Drive, System Control Drive, Motion Control Drive.
Many industrial applications are dependent upon motors (or machines), which range from the size of one's thumb to the size of a railroad locomotive. The motor controllers can be built into the driven equipment, installed separately, installed in an enclosure along with other machine control equipment or installed in motor control centers. Motor control centers are multi-compartment steel enclosures designed to enclose many motor controllers. It is also common for more than one motor controller to operate a number of motors in the same application. In this case the controllers communicate with each other so they can work the motors together as a team.
The most basic is the Standard Drive. ABB manufactures standard drive control by the name of ACS800.
STANDARD DRIVE CONTROL (ACS800)
Genrally ACS800 are vertically installed and there is free space above and below the unit. The design of the cabin or cabinet of ACS800 ensures that there is sufficient cool air in the cabinet to compensate for the power losses.
In ACS800 if the supply network is floating (IT network) both grounding screws are removed otherwise it may lead to accident or damage the unit. Here the motor cables are three phase cables and shielded type. Motor cable are routed away from control wires and the power supply cable to avoid electromagnetic interference. For this kind of drive motor must be a three-phase induction motor and suitable for frequency converter use.
The control of drive may be done by a desktop or control display panel. The drive controls the speed, frequency, torque, power etc.
There are two start-up methods between which the user can select: Run the Start-up Assistant, or perform a limited start-up. Standard ID Run needs to be performed during the drive start-up. (ID Run is essential only in applications which require the ultimate in motor control accuracy.) The ID Run (STANDARD or REDUCED) should be selected if: - The operation point is near zero speed, and/or
Operation at torque range above the motor nominal torque within a wide speed range.
CONTROLLING STANDARD DRIVES
When power is supplied to the drive
Apply mains power. The control panel first shows the panel identification data ...
... then the Identification Display of the
drive...
... then the Actual Signal Display
.. .after which the display suggests starting
the Language Selection.
(If no key is pressed for a few seconds, the
display starts to alternate between the Actual Signal Display and the suggestion on selecting the language.)
The drive is now ready for the start-up.
Selecting Language And starting guided start-up
Press the FUNC key.
Scroll to the desired language by the arrow keys (
press ENTER to accept.
(The drive loads the selected language into use, shifts back to the Actual Signal
Display and starts to alternate between the Actual Signal Display and the
suggestion on starting the guided motor set-up.)
Press FUNC to start the guided motor set-up.
(The display shows which general command keys to use
when stepping through the assistant.)
Press ENTER to step forward.
Language Selection 1/1
LANGUAGE [ENGLISH]
ENTER:OK ACT:EXIT
1 -> 0.0 rpm O *** INFORMATION *** Press FUNC to start guided Motor Setup
Motor Setup 1/10 ENTER: Ok/Continue
ACT: Exit FUNC: More Info
Motor Setup 2/10
MOTOR NAMEPLATE DATA
Follow the instructions given on the display.
AVAILABLE ENTER:Yes FUNC:Info
Manual Start-up
Select the language. The general parameter setting 1 -> 0.0 rpm O
procedure is 9 9 START-UP DATA
01 LANGUAGE
described below. ENGLISH
The general parameter setting procedure:
- Press PAR to select the Parameter Mode of the panel. 1 -> 0.0 rpm O
- Press the double-arrow to scroll the parameter groups. 99 START-UP DATA
- Press the arrow keys to scroll parameters within a 01 LANGUAGE
group. [ENGLISH]
- Activate the setting of a new value by ENTER.
- Change the value by the arrow keys or, fast change by
the double-arrow keys .
- Press ENTER to accept the new value (brackets
disappear).
Select the Application Macro. The general 1 -> 0.0 rpm O 99 START-UP DATA
parameter setting
procedure is given above. 02 APPLICATION MACRO
The default value FACTORY is suitable in [ ]
most cases.
Select the motor control mode. The general
parameter setting 1 -> 0.0 rpm O
procedure is given above. 99 START-UP DATA
04 MOTOR CTRL MODE
DTC is suitable in most cases. The SCALAR [DTC]
control mode is recommended:
- for multimotor drives when the number of the
motors connected to the drive is
variable
- when the nominal current of the motor is less
than 1/6 of the nominal current of Note: Set the motor data to
the inverter exactly the same value as
- when the inverter is used for test purposes on the motor nameplate. For example, if the motor nominal speed is 1440 rpm
with no motor connected.
Enter the motor data from the motor on the nameplate, setting
the value of parameter
nameplate: 99.08 MOTOR NOM
SPEED to 1500 rpm
Identification Magnetisation (Motor ID Run)
Press the LOC/REM key to change to local
control (L shown on the first row). 1 L -> 1242.0 rpm I
Press start to start the Identification Magnetisation. The motor is ** WARNING ** MOTOR STARTS
magnetised at zero speed for 20 to 60 s. Three 1 L-> 0.0 rpm I
warnings are displayed: ** WARNING **
ID MAGN
The first warning is displayed when the 1 L-> 0.0 rpm O
magnetisation starts. ** WARNING ** ID DONE
The second warning is displayed while the
magnetisation is on.
The third warning is displayed after the
magnetisation is completed.
How to start, stop and change direction
STEP ACTION PRESS KEY DISPLAY
1. To show the status row. ACT PAR FUNC 1 ->1242.0 rpm I
FREQ 4 5.00 Hz CURRENT 8 0.00 A POWER 75.00 %
2. To switch to local control. (only if the drive is not under local control, i.e.
there is no L
on the first row of the
display.) LOC
REM 1 L ->1242.0 rpm I
FREQ 45.00 Hz CURRENT 8 0.00 A
POWER 75.00 %
3. To stop V 1 L ->1242.0 rpm O FREQ 4 5.00 Hz CURRENT 8 0.00 A POWER 75.00 %
4. To start o 1 L ->1242.0 rpm I
FREQ 45.00 Hz CURRENT 8 0.00 A POWER 75.00 %
5. To change the direction to reverse. 1 L <-1242.0 rpm I
FREQ 4 5.00 Hz CURRENT 8 0.00 A POWER 75.00 %
6. To change the direction to forward. 1 L ->1242.0 rpm I FREQ 4 5.00 Hz CURRENT 8 0.00 A POWER 75.00 %
Actual signal display mode
In the Actual Signal Display Mode, the user can:
¢ show three actual signals on the display at a time
¢ select the actual signals to display
¢ view the fault history
¢ reset the fault history.
The panel enters the Actual Signal Display Mode when the user presses the ACT key, or if he does not press any key within one minute.
How to display the full name of the actual signals
Step Action Press Key Display
1. To display the full name of the three actual signals. HOLD 1 L -> 12 42.0 rpm I
FREQUENCY
CURRENT
POWER
2. To return to the Actual RESET 1 L -> 12 42.0 rpm I FREQ 45.00 Hz
Signal Display Mode.
CURRENT 80.00 A POWER 75.00 %
FAULT ANALYSIS
Step Action Press key Display
1. To enter the Actual Signal Display Mode. ACT 1 L -> 12 42.0 rpm I FREQ 45.00 Hz CURRENT 80.00 A POWER 75.00 %
2. To enter the Fault History Display. 1 L -> 12 42 . 0 rpm I 1 LAST FAULT +OVERCURRENT
6451 H 21 MIN 23 S
3. To select the previous
UP) orthe next
fault/warning (DOWN). To clear the Fault History. 1 L -> 12 42.0 rpm I
2 LAST FAULT +OVERVOLTAGE
1121 H 1 MIN 23 S
1 L -> 1242.0 rpm I
2 LAST FAULT H MIN S
4. To return to the Actual Signal Display Mode. 1 L -> 12 42.0 rpm I FREQ 45.00 Hz CURRENT 80.00 A POWER 75.00 %
MRW^ 99 START-UP DATA
02 APPLICATION MACRO HAND/AUTO
Drive selection mode
In normal use the features available in the Drive Selection Mode are not needed; the features are reserved for applications where several drives are connected to one panel link. (For more information, see the Installation and Start-up Guide for the Panel Bus Connection Interface Module, NBCI, [3AFY58919748 (English)].
In the Drive Selection Mode, the user can:
¢ Select the drive with which the panel communicates through the panel
link.
¢ Change the identification number of a drive connected to the panel
link.
¢ View the status of the drives connected on the panel link.
How to select a drive and change its panel page link ID number
Step Action Press key Display
1. To enter the Drive Selection Mode. Drive ACS800
ASAAA5 000 xxxxxx ID NUMBER 1
2. To select the next ACS800
drive/view.
The ID number of the station is changed by first pressing ASAAA5000 xxxxxx ID NUMBER 1
ENTER (the brackets 1o
round the ID number
appear) and ARROW UP
then adjusting the value Status Display Symbols:
with arrow buttons. The o = Drive stopped,
new value direction
is accepted with ENTER. forward
The power of the drive = Drive running,
must be direction
switched off to validate its reverse
new ID number setting.
F = Drive tripped on a
The status display of all
fault
devices connected to the
Panel
Link is shown after the
last individual station. If all
stations
do not fit on the display at
once, press the double-
arrow up
to view the rest of them.
3. To connect to the last ACT 1 L-> 12 42.0 rpm I
displayed drive mode, FUNC PAR FREQ 45.00 Hz
press one of the mode
CURRENT 80.00 A
selection keys.
POWER 75.00 %
The selected mode is
entered.
Reading and entering packed boolean values on the display
Some actual values and parameters are packed boolean, i.e. each individual bit has
a defined meaning (explained at the corresponding signal or parameter). On
the
control panel, packed boolean values are read and entered in hexadecimal format.
In this example, bits 1, 3 and 4 of the packed boolean value are ON:
Boolean 0000 0000 0001 1010
Hex 0 0 1 A
NAME DESCRIPTION SET PARAMETERS
Language Select Selecting the language 99.01
Motor Set-up Setting the motor data 99.05, 99.06, 99.09, 99.07, 99.08, 99.04
Application Selecting the application macro 99.02, parameters associated to the macro
Option Modules Activating the option modules Group 98, 35, 52
Speed Control EXT1 Selecting the source for the speed reference
(If AI1 is used: Setting analogue input AI1
limits, scale, inversion)
Setting the reference limits Setting the speed (frequency) limits Setting acceleration and deceleration times 11.03
(13.01, 13.02, 13.03, 13.04, 13.05, 30.01) 11.04, 11.05
20.02, 20.01, (20.08, 20.07)
22.02, 22.03
Torque Control Selecting the source for the torque reference
(If AI1 is used: Setting analogue input AI1
limits, scale, inversion)
Setting the reference limits
Setting the torque ramp up and ramp down
times 11.06
(13.01, 13.02, 13.03, 13.04, 13.05, 30.01) 11.08, 11.07 24.01, 24.02
PID Control Selecting the source for the process reference
(If AI1 is used: Setting analogue input AI1
limits, scale, inversion)
Setting the reference limits Setting the speed (reference) limits Setting the source and limits for the process actual value 11.06
(13.01, 13.02, 13.03, 13.04, 13.05, 30.01)
11.08, 11.07
20.02, 20.01 (20.08, 20.07) 40.07, 40.09, 40.10
Start/Stop Control Selecting the source for start and stop signals of the two external control locations, EXT1 and EXT2 Selecting between EXT1 and EXT2 Defining the direction control Defining the start and stop modes Selecting the use of Run Enable signal Setting the ramp time for the Run Enable function 10.01, 10.02
11.02
10.03
21.01, 21.02, 21.03 16.01, 21.07
22.07
Protections Setting the torque and current limits 20.03, 20.04
Contents of the assistant displays
There are two types of displays in the Start-up Assistant: The main displays and the information displays. The main displays prompt the user to feed in information or answer a question. The assistant steps through the main displays. The information displays contain help texts for the main displays. The figure below shows a typical example of both and explanations of the contents.
Main Display Information Display
Motor Setup 3/10 INFO P99.05
MOTOR NOM VOLTAGE Set as given on the
[0 V] motor
ENTER:Ok RESET:Back nameplate.
Local control vs. External control
The drive can receive start, stop and direction commands and reference values from the control panel or through digital and analogue inputs. An optional fieldbus adapter
enables control over an open fieldbus link. A PC equipped with DriveWindow can also control the drive.
Control Panel Connector
Terminal Interface, wall mounted (ACS800-01/-U1)
X20 Voltage reference-10V
X21 Analog Inputs and outputs
Option slot 1
(RAIO option connected)
Option slot 2
(RDIO option connected)
X22 Digital Inputs
X23 Voltage reference *24V
Option slot 3
(RDCO option connected)
X24 Relay Output 1
X25 Relay Output 2
X26 Relay Output 3
Terminal blocks of the RMIO board: I
Ul VI Wl R- R+ U2 V2 W2
(Pover Supply) || Vdc* Udc- || (Motor Connection)
Local control
The control commands are given from the control panel keypad when the drive is in local control. L indicates local control on the panel display.
1Q->1242 rpm I
The control panel always overrides the external control signal sources when used in local mode.
External control
When the drive is in external control, the commands are given through the standard I/O terminals (digital and analogue inputs), optional I/O extension modules and/or the fieldbus interface. In addition, it is also possible to set the control panel as the source for the external control.
External control is indicated by a blank on the panel display or with an R in those special cases when the panel is defined as a source for external control.
1 Q ->1242 rpm I 1 fp)->1242 rpm I
External Control through the Input/ External Control by control panel Output terminals, or through the fieldbus interfaces
The user can connect the control signals to two external control locations, EXT1 or EXT2. Depending on the user selection, either one is active at a time. This function operates on a 12 ms time level.
Reference trimming
In reference trimming, the external %-reference (External reference REF2) is corrected depending on the measured value of a secondary application variable. The block diagram below illustrates the function.
EXAMPLE:
The drive runs a conveyor line. It is speed-controlled but the line tension also needs to be taken into account: If the measured tension exceeds the tension setpoint, the speed will be slightly decreased, and vice versa.
To accomplish the desired speed correction, the user:
¢ activates the trimming function and connects the tension setpoint and the
measured tension to it
¢ tunes the trimming to a suitable level.
Drive Rollers(pull)
Simplified Block Diagram
Speed Reference
ADD
Speed controlled conveyor line
PID
Tension Measurement
Trimmed speed reference
Tension Setpoint
Programmable analogue inputs
The drive has three programmable analogue inputs: one voltage input (0/2 to 10 V or -10 to 10 V) and two current inputs (0/4 to 20 mA). Two extra inputs are available if an optional analogue I/O extension module is used. Each input can be inverted and filtered, and the maximum and minimum values can be adjusted.
Programmable analogue outputs
Two programmable current outputs (0/4 to 20 mA) are available as standard, and two outputs can be added by using an optional analogue I/O extension module. Analogue output signals can be inverted and filtered.
The analogue output signals can be proportional to motor speed, process speed (scaled motor speed), output frequency, output current, motor torque, motor power, etc.
It is possible to write a value to an analogue output through a serial communication
link.
Motor identification
The performance of Direct Torque Control is based on an accurate motor model determined during the motor start-up.
A motor Identification Magnetisation is automatically done the first time the start command is given. During this first start-up, the motor is magnetised at zero speed for several seconds to allow the motor model to be created. This identification method is suitable for most applications.
In demanding applications a separate Identification Run can be performed.
Settings
Parameter 99.10.
Power loss ride-through
If the incoming supply voltage is cut off, the drive will continue to operate by utilising the kinetic energy of the rotating motor. The drive will be fully operational as long as the motor rotates and generates energy to the drive. The drive can continue the operation after the break if the main contactor remained closed.
Note: Cabinet assembled units equipped with main contactor option have a .hold circuit. that keeps the contactor control circuit closed during a short supply break. The allowed duration of the break is adjustable. The factory setting is five seconds.
DC Magnetising
When DC Magnetising is activated, the drive automatically magnetises the motor before starting. This feature guarantees the highest possible breakaway torque, up to 200% of motor nominal torque. By adjusting the premagnetising time, it is possible to synchronise the motor start and e.g. a mechanical brake release. The Automatic Start feature and DC Magnetising cannot be activated at the same time. Settings
Parameters 21.01 and 21.02.
DC Hold
By activating the motor DC Hold feature it is possible to lock the rotor at zero speed. When both the reference and the motor speed fall below the preset DC hold speed, the drive stops the motor and starts to inject DC into the motor. When the reference speed again exceeds the DC hold speed, the normal drive operation resumes.
Flux Braking
The drive can provide greater deceleration by raising the level of magnetisation in the motor. By increasing the motor flux, the energy generated by the motor during braking can be converted to motor thermal energy. This feature is useful in motor power ranges below 15 kW.
. The cooling of the motor is efficient. The stator current of the motor increases during the Flux Braking, not the rotor current. The stator cools much more efficiently than the rotor. Settings
Parameter 26.02.
Scalar control
It is possible to select Scalar Control as the motor control method instead of Direct Torque Control (DTC). In the Scalar Control mode, the drive is controlled with a frequency reference. The outstanding performance of the default motor control method, Direct Torque Control, is not achieved in Scalar Control.
It is recommended to activate the Scalar Control mode in the following special
applications:
. In multimotor drives:
1) if the load is not equally shared between the motors,
2) if the motors are of different sizes, or
3) if the motors are going to be changed after the motor identification
. If the nominal current of the motor is less than 1/6 of the nominal output current of the drive
. If the drive is used without a motor connected (e.g. for test purposes)
. The drive runs a medium voltage motor via a step-up transformer.
In the Scalar Control mode, some standard features are not available.
Settings
Parameter 99.04.
IR compensation for a scalar controlled drive
IR Compensation is active only when the motor control mode is Scalar (see section Scalar control on page 60). When IR Compensation is activated, the drive gives an extra voltage boost to the motor at low speeds. IR Compensation is useful in applications that require high breakaway torque. In Direct Torque Control, no IR Compensation is possible/needed.
Settings
Parameter 26.03.
Motor Thermal Protection
The motor can be protected against overheating by activating the Motor Thermal Protection
function and by selecting one of the motor thermal protection modes available.
The Motor Thermal Protection modes are based either on a motor temperature thermal model or
on an overtemperature indication from a motor thermistor.
Motor temperature thermal model
The drive calculates the temperature of the motor on the basis of the following assumptions:
1) The motor is at the estimated temperature (value of 01.37 MOTOR TEMP TEST saved at power switch off) when power is applied to the drive. When power is applied for the first time, the motor is at the ambient temperature (30°C).
2) Motor temperature is calculated using either the user-adjustable or automatically calculated motor thermal time and motor load curve (see the figures below). The load curve should be adjusted in case the ambient temperature exceeds 30°C.
Use of the motor thermistor
It is possible to detect motor overtemperature by connecting a motor thermistor (PTC) between the +24 VDC voltage supply offered by the drive and digital input DI6. In normal motor operation temperature, the thermistor resistance should be less than 1.5 kohm (current 5 mA). The drive stops the motor and gives a fault indication if the thermistor resistance exceeds 4 kohm. The installation must meet the regulations for protecting against contact. Settings
Parameters 30.04 to 30.09. Stall Protection
The drive protects the motor in a stall situation. It is possible to adjust the supervision limits (torque, frequency, time) and choose how the drive reacts to a motor stall condition (warning
indication / fault indication & stop the drive / no reaction). The torque and current limits, which define the stall limit, must be set according to the maximum load of the used application. Note: Stall limit is restricted by internal current limit 03.04 TORQ_JNV_CTJR_LJM. When the application reaches the stall limit and the output frequency of the drive is below the stall frequency: Fault is activated after the stall time delay. Settings
Parameters 30.10 to 30.12.
Parameters 20.03, 20.13 and 20.14 (Define the stall limit.) Underload Protection
Loss of motor load may indicate a process malfunction. The drive provides an underload function to protect the machinery and process in such a serious fault condition. Supervision limits - underload curve and underload time - can be chosen as well as the action taken by the drive upon the underload condition (warning indication / fault indication & stop the drive / no reaction). Settings
Parameters 30.13 to 30.15. Motor Phase Loss
The Phase Loss function monitors the status of the motor cable connection. The function is useful especially during the motor start: the drive detects if any of the motor phases is not connected and refuses to start. The Phase Loss function also supervises the motor connection status during normal operation.
Settings
Parameter 30.16. Earth Fault Protection
The Earth Fault Protection detects earth faults in the motor or motor cable. The protection is based on sum current measurement.
. An earth fault in the mains does not activate the protection.
. In an earthed (grounded) supply, the protection activates in 200 microseconds.
. In floating mains, the mains capacitance should be 1 microfarad or more.
. The capacitive currents due to screened copper motor cables up to 300 metres do not activate
the protection.
. Earth fault protection is deactivated when the drive is stopped.
Note: With parallel connected inverter modules, the earth fault indication is
CUR UNBAL.
Settings
Parameter 30.17. Communication Fault
The Communication Fault function supervises the communication between the drive and an external control device (e.g. a fieldbus adapter module).
Settings
Parameters 30.18 to 30.21. Supervision of optional IO
The function supervises the use of the optional analogue and digital inputs and outputs in the application program, and warns if the communication to the input/output is not operational.
Settings
Parameter 30.22.
Preprogrammed faults Overcurrent
The overcurrent trip limit for the drive is 1.65 to 2.17 ¢ /max depending on the drive type. DC overvoltage
The DC overvoltage trip limit is 1.3 ¢ U1max, where U1max is the maximum value of the mains voltage range. For 400 V units, U1max is 415 V. For 500 V units, U1max is 500 V. For 690 V units, U1max is 690 V. The actual voltage in the intermediate circuit corresponding to the mains voltage trip level is 728 VDC for 400 V units, 877 VDC for 500 V units, and 1210 VDC for 690 V units.
DC undervoltage
The DC undervoltage trip limit is 0.6 ¢ Ui min, where Uimin is the minimum value of the mains voltage range. For 400 V and 500 V units, Uimin is 380 V. For 690 V units, Uimin is 525 V. The actual voltage in the intermediate circuit corresponding to the mains voltage trip level is 307 VDC for 400 V and 500 V units, and 425 VDC for 690 V units.
Drive temperature
The drive supervises the inverter module temperature. There are two supervision limits: warning limit and fault trip limit.
Enhanced drive temperature monitoring for ACS800-U2, -U4 and -U7, frame sizes
R7 and R8
Traditionally, drive temperature monitoring is based on the power semiconductor (IGBT) temperature measurement which is compared with a fixed maximum IGBT temperature limit. However, certain abnormal conditions such as cooling fan failure, insufficient cooling air flow or excessive ambient temperature might cause overheating inside the converter module, which the traditional temperature monitoring alone does not detect. The Enhanced drive temperature monitoring improves the protection in these situations. The function monitors the converter module temperature by checking cyclically that the measured IGBT temperature is not excessive considering the load current, ambient temperature, and other factors that affect the temperature rise inside the converter module. The calculation uses an experimentally defined equation that simulates the normal temperature changes in the module depending on the load. Drive generates a warning when the temperature exceeds the limit, and trips when temperature exceeds the limit
by 5°C.
Application macros
Application macros are preprogrammed parameter sets. While starting up the drive, the user typically selects one of the macros - the one that is best suited to his needs - by parameter 99.02, makes the essential changes and saves the result as a user macro.
There are five standard macros and two user macros. The table below contains a summary of the
macros and describes suitable applications.
MACRO SUITABLE APPLICATION
Factory Ordinary speed control applications where no, one, two or three constant speeds are used:
- Conveyors
- Speed-controlled pumps and fans
- Test benches with predefined constant speeds
Hand/Auto Speed control applications. Switching between two external control devices is possible.
PID Control Process control applications e.g. different closed loop control systems such as pressure control, level control, and flow control. For example:
- pressure boost pumps of municipal water supply systems
- level controlling pumps of water reservoirs
- pressure boost pumps of district heating systems
- material flow control on a conveyor line.
It is also possible to switch between process and speed control.
Torque Control Torque control applications. Switching between torque and speed control is possible.
Sequential Control Speed control applications in which speed reference, seven constant speeds and two acceleration and deceleration ramps can be used.
User The user can save the customised standard macro i.e. the parameter settings including group 99, and the results of the motor identification into the permanent memory, and recall the data at a later time. Two user macros are essential when switching between two different motors is required
Hand/Auto macro
Start/Stop and Direction commands and reference settings can be given from one of two external control locations, EXT1 (Hand) or EXT2 (Auto). The Start/Stop/Direction commands of EXT1 (Hand) are connected to digital inputs DI1 and DI2, and the reference signal is connected to analogue input AI1. The Start/Stop/Direction commands of EXT2 (Auto) are connected to digital inputs DI5 and DI6, and the reference signal is connected to analogue input AI2. The selection between EXT1 and EXT2 is dependent on the status of digital input DI3. The drive is speed controlled. Speed reference and Start/Stop and Direction commands can be given from the control panel keypad also. One constant speed can be selected through digital input DI4. Speed reference in Auto Control (EXT2) is given as a percentage of the maximum speed of the drive. Two analogue and three relay output signals are available on terminal blocks. The default signals on the display of the control panel are FREQUENCY, CURRENT and
CTRL LOC.
PID Control macro
The PID Control macro is used for controlling a process variable . such as pressure or flow . by controlling the speed of the driven motor. Process reference signal is connected to analogue input AI1 and process feedback signal to analogue input AI2.
Alternatively, a direct speed reference can be given to the drive through analogue input AI1. Then the PID controller is bypassed and the drive no longer controls the process variable.
Selection between the direct speed control and the process variable control is done with digital input DI3. Two analogue and three relay output signals are available on terminal blocks. The default signals on the display of the control panel are SPEED, ACTUAL VALUE1 and CONTROL DEVIATION.
Connection example, 24 VDC / 4.20 mA two-wire sensor
Default control connections
The figure below shows the external control connections for the PID Control macro. The markings of the standard I/O terminals on the RMIO board are shown.
Default control connections
Time
The above picture shows the evolution of drives as manufactured by ABB. There is always a scope of research and development. Nowadays the series being manufactured is ACS800. But the usage of standard drive is becoming less and less popular as well. Now System drives are becoming popular and they are the one also known as engineering drives. The system drives are used for specific and precised work. They are generally used for servo motors as the required precission is more and tolerance is reduced.
Nowadays multidrive system is becoming popular as there is less power loss and output is more. The energy lost in converting AC to DC and DC to AC is reduced as they use IGBT. Now the direct torque control technique is the most preferred one. Day by day development i
