Family Background of Edgar Sia Essay

1. * Electronic Controller uses electrical signals and digital algorithms to perform its receptive, comparative and corrective functions. is best suited for applications where large load changes are encountered and/or fast response changes are required. Trerice Electronic Controllers have full auto tuning and PID capabilities, and offer a host of available options, including user selectable inputs and ranges, outputs, setback functions, and alarms. An economical â€Å"on/off† only style is also available for simple control applications. * Electromechanical controller is a type of traffic signal controller. Despite the fact that computerized traffic signal controllers have dominated the world of traffic signal control, electromechanical traffic signal controllers are still in existence. Electromechanical controllers have been in existence for over 60 years, and they are interesting in many ways, such as how they operate, for example. An electromechanical controller is solely operated by electrical relays. Electrical relays are what provide electrical currents to the important parts that are responsible for controlling the indications of a traffic signal that the electromechanical traffic signal controller is wired to * ELECTRICAL CONTROLLER For actuating a number of electrical devices in accordance with control inputs received from a number of control input sources includes a number of optical isolators having inputs coupled to the control input sources. The optical isolators function to electrically isolate each of the control input sources from each other and to provide individual control voltages corresponding to the control inputs received from the control input sources. The outputs of the optical isolators are coupled through a user-actuable matrix switch to the coils of a number of relays which, in turn, control the electrical devices. Through various settings of the matrix switch, various ones of the electrical devices can be actuated in response to control inputs received from particular ones of the control input sources. Electrical isolation is maintained among the control input sources to avoid the development of undesirable feedbacks to the non-actuated control input sources. * Mechanical Controllers combine sensors, logic, and actuators to maintain the performance of components of a machine. Perhaps the best known is the flyball governor for a steam engine. Examples of these devices range from a thermostat that as temperature rises opens a valve to cooling water to speed controllers such the cruise control system in an automobile. The programmable logic controller replaced relays and specialized control mechanisms with a programmable computer. Servomotors that accurately position a shaft in response to an electrical command are the actuators that make robotic systems possible. 2.) * Motor control * PWM controller * DC-DC controller * Switched mode power supply a) SWITCH is an electrical component that can break anelectrical circuit, interrupting the current or diverting it from one conductor to another.[1][2] The most familiar form of switch is a manually operated electromechanicaldevice with one or more sets of electrical contacts, which are connected to external circuits. Each set of contacts can be in one of two states: either â€Å"closed† meaning the contacts are touching and electricity can flow between them, or â€Å"open†, meaning the contacts are separated and the switch is nonconducting. The mechanism actuating the transition between these two states (open or closed) can be either a â€Å"toggle† (flip switch for continuous â€Å"on† or â€Å"off†) or â€Å"momentary† (push-for â€Å"on† or push-for â€Å"off†) type. A switch may be directly manipulated by a human as a control signal to a system, such as a computer keyboard button, or to control power flow in a circuit, such as a light switch. Automatically operated switches can be used to control the motions of machines, for example, to indicate that a garage door has reached its full open position or that a machine tool is in a position to accept another workpiece. Switches may be operated by process variables such as pressure, temperature, flow, current, voltage, and force, acting assensors in a process and used to automatically control a system. For example, a thermostat is a temperature-operated switch used to control a heating process. A switch that is operated by another electrical circuit is called a relay. Large switches may be remotely operated by a motor drive mechanism. Some switches are used to isolate electric power from a system, providing a visible point of isolation that can be padlocked if necessary to prevent accidental operation of a machine during maintenance, or to prevent electric shock. An ideal switch would have no voltage drop when closed, and would have no limits on voltage or current rating. It would have zero rise time and fall time during state changes, and would change state without â€Å"bouncing† between on and off positions. Practical switches fall short of this ideal; they have resistance, limits on the current and voltage they can handle, finite switching time, etc. The ideal switch is often used in circuit analysis as it greatly simplifies the system of equations to be solved, however this can lead to a less accurate solution. Theoretical treatment of the effects of non-ideal properties is required in the design of large networks of switches, as for example used in telephone exchanges. b) RELAY is an electrically operated switch. Many relays use an electromagnet to operate a switching mechanism mechanically, but other operating principles are also used. Relays are used where it is necessary to control a circuit by a low-power signal (with complete electrical isolation between control and controlled circuits), or where several circuits must be controlled by one signal. The first relays were used in long distance telegraph circuits, repeating the signal coming in from one circuit and re-transmitting it to another. Relays were used extensively in telephone exchanges and early computers to perform logical operations. A type of relay that can handle the high power required to directly control an electric motor or other loads is called a contactor. Solid-state relays control power circuits with no moving parts, instead using a semiconductor device to perform switching. Relays with calibrated operating characteristics and sometimes multiple operating coils are used to pro tect electrical circuits from overload or faults; in modern electric power systems these functions are performed by digital instruments still called â€Å"protective relays†. c) COIL is formed when a conductor (usually an insulated solid copper wire) is wound around a core or form to create an inductor or electromagnet. When electricity is passed through a coil, it generates heat. One loop of wire is usually referred to as aturn, and a coil consists of one or more turns. For use in an electronic circuit, electrical connectionterminals called taps are often connected to a coil. Coils are often coated with varnish or wrapped with insulating tape to provide additional insulation and secure them in place. A completed coil assembly with taps is often called a winding. A transformer is an electromagnetic device that has aprimary winding and a secondary winding that transfers energy from one electrical circuit to another by inductive coupling without moving parts. The term tickler coil usually refers to a feedback coil, which is often the third coil placed in relation to a primary coil and secondary coil. A coil tap is a wiring feature found on some electrical transformers, inductors and coil pickups, all of which are sets of wire coils. The coil tap(s) are points in a wire coil where a conductive patch has been exposed (usually on a loop of wire that extends out of the main coil body). As self induction is larger for larger coil diameter the current in a thick wire tries to flow on the inside. The ideal use of copper is achieved by foils. Sometimes this means that a spiral is a better alternative. Multilayer coils have the problem of interlayer capacitance, so when multiple layers are needed the shape needs to be radically changed to a short coil with many layers so that the voltage between consecutive layers is smaller (making them more spiral like).