Service of Controllers
Service of Controllers – The job of a control system is to monitor and operate other connected mechanisms i.e. devices or systems and ensure their proper functioning. Its applications can be very extensive, from a simple thermostat controller that it used for heat control of a boiler, to an enormous control system of the industry which is used to regulate the operations of various machines and their associated processes.
The most typical example of this is that of the control system for the feedback in which a plant is controlled which is a process. As a result a control signal is generated. This signal can have either a fixed value or a modifying value. The job of the control system is to check the plant’s output against the generated control signal. The difference between the two is termed as the error signal and this is applied such that the actual output can be brought closer to the generated control signal.
There are manual systems and controls that are used by the operator and this is what a control system fundamentally means. These controls can be the closing or opening of a hydraulic press as an example. Certain logic can also be implemented, for example any safety precaution in terms of safety guards for this hydraulic press.
Service of Controllers – A control system can also be automatic and a sequential control. It can be used to operate a line of mechanical actuators that can be activated in a specific order so that a specific task is performed. An example of this would be that that there can be numerous electric and inflatable sensors that work together and get a box of cardboard folded and glued. The box can then be filled with something before it is packed and sealed by a packaging machine which is automatic. The logic controllers that can be programmed can be made use of in many such applications, however, various alternative methodologies also exist.
When we talk about a feedback system that is linear, it has various components including a control loop, sensors, algorithms and actuators, which are all put up in a specific arrangement so that a variable can be controlled and regulated at some specific set point or a value for reference. An example of this would be that when a specific temperature measurement falls, the quantity of the supplied fuel to the furnace would automatically increase as per requirements. For such purposes, mostly PID controllers are adequately used. Some control systems can also adjust to changing circumstances due to their usage of feedback. These kinds of systems make use of some kind of sensing in terms of the results and targets that are to be achieved. When it comes to open-loop control systems, they do not operate using any sort of feedback and their operations’ arrangements are already pre-specified.
Service of Controllers – In terms of physical implementations, the latest microprocessors are small and cheaply affordable too, which is why it’s very typical to make use of embedded systems for the implementation of control systems, complete with feedback loops and computers.
Service of Drives
What is the definition of a “variable frequency drive”?
Service of Drives – A variable frequency drive, or VFD for short, is basically a motor controller. Its job is to vary and change the frequencies and the supply voltage of the related electric motor so that its speed can be kept in check when it is driven. A variable speed drive is known by many other names which include modifiable speed drive, modifiable frequency drive, AC drive, micro-drive and inverter.
Service of Drives – There is a directly proportional relationship between the frequency and the motor speed. Frequency is measured in hertz while motor’s speed is measured as revolutions per minute i.e. RPMs. In simpler words, the more speedy the frequency, the speedier the RPMs will be. If the requirements of the application are such that there is no need of running the motor at full speed, a variable frequency drive comes in handy by turning down the frequency and voltage so that it is all balanced and in accordance with the electric motors load. With time the application’s motor speed requirements can and do vary, and a variable frequency drives ensures that the speed is modified, turned up or down, and all of the requirements are met.
What is the working of a variable frequency drive?
Service of Drives – The converter is the very first part of a variable frequency AC drive i.e. VFD. Six diodes make up the composition of the converter. The working of these diodes is similar to the working of check valves which are part of a plumbing system. A diode restricts the movement or flow of current to only one direction. This direction is specified by an arrow that makes up a diode symbol. In the following example, voltage is the counterpart of pressure in a plumbing system. The example is such that if at a moment the A phase voltage has higher positivity as compared to B or C phase voltages then A phase diode will let the current to flow through it. If after that the B phase’s positivity becomes higher than that of A phase then that diode will open resulting in the closure of A phase diode. There will be the same working for the three diodes that are present on the side of the bus that is negative. After the opening and closing of all the diodes, we are able to get six current pulses. This configuration is known as a “six pulse variable frequency drive”. This is also the standard configuration that is typical for current variable frequency drives.
Benefits of using a VFD
Numerous advantages are provided by a variable frequency drive, which are listed as follows:
- The first one is the conservation of energy
- No more need of costly machineries for mechanical driving.
- Motor’s endurance and life is increased significantly
- The power line noises are lessened.
- There is also significant reduction in the danger of motor damage that occurs during the starting up and stopping.
Some of these benefits can be compromised as a result of poor practice, but the energy conservation is enough justification on its own.
Service of HMI
Service of HMI – There are numerous benefits to using a human machine interface and some of the most important ones are listed below as following.
- The machineries and procedures consist of very good quality of graphics so that all of the representations are realistically relatable.
Service of HMI – Due to this, the operator and the administration involved will be able to visualize a very real-like view of the plant. It becomes possible for the operator to handle all processes of the plant from one core location. This is also beneficial when security fears arise. Things are made easier for the operator as well who does not have to be in close proximity to the plant at all times in order to manage or monitor it.
- Both real-time and historical alarms data
Service of HMI – The operator of the interface can easily view alarms i.e. he or she can place and also respond quicker to any sort of malfunction or any anomaly. The alarms can be of different types, with one being the preventive type. This is the type in which a warning is generated for example when the oil level goes below a critical value in a hydraulic tank.
Historical alarm means that the alarms are logged and this is particularly useful when it comes to tracking of issues. It also contributes to the process optimization. And as a result of optimization, both the overall productivity and the total time lost are improved.
- Both real-time and historical trends
Service of HMI – Trends data comes in very handy in terms of PIDs. The curve made use of for the attainment of a specific set point can be easily visualized. This study of the set points and their attainment will help to optimize the whole process and increase the level of efficiency significantly.
- Recipe Manager
Both the simpler and complex recipes can be managed using HMI. The execution of recipes becomes much more effective.
There are some HMIs that are of such good quality that an operator can visualize a full-fledge simulation in just an office. This enables the PLC programmers to test their programs without even a single piece of plant equipment. This helps in significant reduction in the startup time.
The operator can message, page or fax any concerned person whenever there is the occurrence of a specific event. The animation and instrument depend on the standards of the operator.
The picture that will be generated is not just a picture but a complete animated picture. This will help significantly towards visualizing of the whole process and system. As a result, effectiveness and efficiency of anomaly detection will also be enhanced.
- Reduction in hardware expenses
The operator panel goes from countless buttons, selectors and lights etc. to just one human machine interface. This means that ultimately the hardware expenses are lessened as number of controls and cables minimizes.
An extensive variety of human machine interfaces are able to communicate with a variety of the most typical and common PLCs. These communications include serial port, Ethernet, remote I/O, DDE etc.
Service of HVAC Control System
HVAC Control System – The hardware used for heating, ventilation and air conditioning i.e. HVAC requires a control system that handles and manages the processing of residential systems including an air conditioning system or a heating system. The working of this control system involves the usage of a sensing mechanism. This device senses the actual conditions in the environment and then compares that data with desirable conditions data. After this comparison a conclusion is inferred as to what measure needs to be implemented so as to minimize the variance between the two states e.g. starting of the compressor.
Direct Digital Control
HVAC Control System – A central along with almost all of the terminal unit controllers can be programmed if required. This means that there is plenty room for customization of the direct digital control or DDC program code so that it is fully adapted to whatever specific use is required. There are a number of features available which include timers and scheduling, notifications, log of historic data, controllers, logic components and setpoints. There are usually two different types of inputs in unit controller i.e. analog and digital inputs. Using these inputs, the outside variable conditions can be measured. These variables include temperature, humidity and pressure. There are also two types of outputs i.e. analog and digital outputs. These channels are used for controlling of the transport substance. The substance can be water of any temperature and/or steam. In case of the digital inputs, they are usually dry contacts that are connected to a device for control. The analog inputs are usually measured in either voltage or current from a device used for environment sensing including temperature, humidity, velocity or pressure. The digital outputs are basically relay contacts. These relays are usually used for the starting or stopping of the machinery. The analog outputs are basically electric signals that can be of either voltage or current. They are used for controlling of the medium control mechanism’s movements i.e. of air, water or steam. The devices include valves, dampers and motors.
A layer is formed from clusters of DDC controllers. This feature is central to the whole system’s operation. It plays the role of the “brain” of the whole system. It generates instructions for the operation of the rest of the devices.
Building automation system
HVAC Control System – There are some complicated HVAC systems that allow their users to have more say in the running of the temperature regulating units by having an interface connection to the Building Automation system. This enables the owner of the construction to react to the alarm notifications even if they are not present at the locality but are at some remote location. A scheduling feature is part of the system through which occupancy scheduling can be achieved or it so is the case that the configuration is subject to direct modification from the building automation system. It is also not unusual to see that the HVAC equipment and hardware is manipulated directly from the building automation system for more control. The type of interfacing used is dependent on the type of the building automation systems.
Service of Indl Automation System
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