ELECTRICAL ENCYCLOPEDIA

What is a SCADA?   The term SCADA usually refers to centralized systems which monitor and control entire sites, or complexes of systems spread out over large areas (anything from an industrial plant to a nation). Most control actions are performed automatically by RTUs or by PLCs. Host control functions are usually restricted to basic overriding or supervisory level intervention. For example, a PLC may control the flow of cooling water through part of an industrial process, but the SCADA system may allow operators to change the set points for the flow, and enable alarm conditions, such as loss of flow and high temperature, to be displayed and recorded. The feedback control loop passes through the RTU or PLC, while the SCADA system monitors the overall performance of the loop.  continue.. History of SCADA   SCADA (supervisory control and data acquisition) has been around as long as there have been control systems. The first ‘SCADA’ systems utilized data acquisition by means of panel

What is a SONAR?   Sonar (originally an acronym for SOund Navigation And Ranging) is a technique that uses sound propagation (usually underwater, as in submarine navigation) to navigate, communicate with or detect other vessels. Two types of technology share the name "sonar": passive sonar is essentially listening for the sound made by vessels; active sonar is emitting pulses of sounds and listening for echoes. Sonar may be used as a means of acoustic location and of measurement of the echo characteristics of "targets" in the water. Acoustic location in air was used before the introduction of radar.  continue.. History of SONAR   Sonar is a system that uses transmitted and reflected underwater sound waves to detect and locate submerged objects or measure the distances underwater. It has been used for submarine and mine detection, depth detection, commercial fishing, diving safety and communication at sea. The Sonar device will send out a subsurface sound wave an

What is a RADAR?   Radar is an object-detection system which uses radio waves to determine the range, altitude, direction, or speed of objects. It can be used to detect aircraft, ships, spacecraft, guided missiles, motor vehicles, weather formations, and terrain. The radar dish or antenna transmits pulses of radio waves or microwaves which bounce off any object in their path. The object returns a tiny part of the wave's energy to a dish or antenna which is usually located at the same site as the transmitter.  continue.. History of RADAR   In 1934 a large-scale Air Defence exercise was held to test the defences of Great Britain and mock raids were carried out on London. Even though the routes and targets were known in advance, well over half the bombers reached their targets without opposition. Prime Minister Baldwin's statement "The bomber will always get through" seemed true. To give time for their guns to engage enemy aircraft as they came over, the Army was ex

What is a Short CIrcuit?   A short circuit is an abnormal low-resistance connection between two nodes of an electrical circuit that are meant to be at different voltages. This results in an excessive electric current (overcurrent) limited only by the Thévenin equivalent resistance of the rest of the network and potentially causes circuit damage, overheating, fire or explosion. Although usually the result of a fault, there are cases where short circuits are caused intentionally, for example, for the purpose of voltage-sensing crowbar circuit protectors.  continue.. Short Circuit Definition   An electrical path in a circuit that causes most of the current to flow around or away from some other path in the circuit. Accidental short circuits, especially between the high and low voltages of a power supply, can cause very strong current to flow, possibly damaging or overheating the circuit.  continue.. Resistance Review for Short Circuit Understanding   The circuit in the previous se

What is Arc Welding?   Arc welding is a type of welding that uses a welding power supply to create an electric arc between an electrode and the base material to melt the metals at the welding point. They can use either direct (DC) or alternating (AC) current, and consumable or non-consumable electrodes. The welding region is usually protected by some type of shielding gas, vapor, and/or slag.  continue.. Robotic Arc Welding   Robot welding means welding that is performed and controlled by robotic equipment. In general equipment for automatic arc welding is designed differently from that used for manual arc welding. Automatic arc welding normally involves high duty cycles, and the welding equipment must be able to operate under those conditions. In addition, the equipment components must have the necessary features and controls to interface with the main control system.  continue.. Welding Basics for You and Me   In its most basic form, a welder is a device that melts two piece

ANSI Device Numbers   In the design of electrical power systems, the ANSI Standard Device Numbers (ANSI /IEEE Standard C37.2) denote what features a protective device supports (such as a relay or circuit breaker). These types of devices protect electrical systems and components from damage when an unwanted event occurs, such as an electrical fault. Device numbers are used to identify the functions of devices shown on a schematic diagram. Function descriptions are given in the standard.  continue.. ANSI Device Numbers Easy Page Guide   Device numbers may be combined if the device provides multiple functions, such as the instantaneous/time-delay AC over current relay denoted as 50/51  continue.. ANSI Codes – Device Designation Numbers   In the design of electrical power systems, the ANSI Standard Device Numbers (ANSI /IEEE Standard C37.2) denote what features a protective device supports (such as a relay or circuit breaker). These types of devices protect electrical systems and c

Cable thief electrocuted in Minna - Nigerian Tribune   Cable thief electrocuted in MinnaNigerian TribuneTRAGEDY struck in Minna, Niger State capital, last Saturday as an unidentified young man, suspected to be in his 20s, was electrocuted while attempting to vandalise an underground electric cable connected to a transformer, some 200 meters away from the .... continue.. Horses Electrocuted in Racecourse Tragedy   (NEWSER) – Two prize racehorses began prancing grotesquely, then staggered and fell dead on a patch of grass before a British race over the weekend. The horrifying spectacle unfolded in front of a stunned crowd watching the riderless horses being led around the infield paddock of the Newbury track. Official speculated they were killed by a faulty electrical cable buried beneath the ground, reports the Independent.  continue.. Brazilian partygoers electrocuted   AT least 16 were killed and 50 injured in a freak electrocution during a large parade in southeastern Brazil.