Control systems like control panels, transformers like potential, current protective relays & connected circuitry that controls, monitors & protect the components of power conducting. For example, if only one of two sources of supply are permitted to be connected at a given time, the interlock scheme may require that the first switch must be opened to release a key that will allow closing the second switch. Once the short circuit occurs within the power system, then a huge current will flow through the devices. What is the difference between a switchboard and switchgear? To understand where each fits, we will have a look at their functions and differences. Other common switchgear power systems include oil insulated and vacuum switchgear. There are many different types of switches, and we will explore some of these types in this chapter. Switches are essentially binary devices: they are either completely on (closed) or completely off (open). Its design is verified in accordance with IEC 61439-1/-2. Switches: A switch is a static device, which is use to open or close an electrical circuit in a convenient way. The wall switch is one of the most common and important electrical devices in the home. They are usually metal enclosed outdoor type, metal enclosed indoor type, indoor or outdoor type without the metal enclosure, and so forth. See our further post also for detailed knowledge of these devices. As a result, during the designing of this equipment, special care has to be taken. For reasons of fire protection, the wood was replaced by slate or marble. Alternatively referred to as a cord, connector or plug, a cable is one or more wires covered in plastic that transmit power or data between devices or locations. Circuit breakers are usually able to terminate all current flow very quickly: typically between 30 ms and 150 ms depending upon the age and construction of the device. At present, the demand for electrical power is growing rapidly, and this can be fulfilled by the power generating substations. Complex schemes are possible. Circuit breakers with vacuum interrupters have minimal arcing characteristics (as there is nothing to ionize other than the contact material), so the arc quenches when it is stretched by a small amount (<2–8 mm). Whenever there is a separation of current carrying contacts in the oil, the arc in circuit breaker is initialized at the moment of separation of contacts, and due to this arc the oil is vaporized and decomposed in mostly hydrogen gas and ultimately creates a hydrogen bubble around the electric arc. The current through both ends should be identical. A ring main unit is a type of switchgear. See our further post also for detailed knowledge of these devices. Gas-insulated switchgear saves space compared with air-insulated equipment, although the equipment cost is higher. The main functions of this equipment include the following. This is capable of ON/OFF operation, interruption of short circuit current, capacitive current switching, inductive current switching and used in some special applications. It is placed in both the high and low... Types of Switchgear:. There are a number of methods of construction of substations depending on the switchgear type. A switchgear may be a simple open-air isolator switch or it may be insulated by some other substance. When a user presses the button, its metal plate connects with each other, hence the circuit is completed. A. Switchgears . D. Transformation stations Switchgear is equipment that can be used to switch high voltage electrical circuits in and out. 3. The term ‘switchgear’ is a generic term that includes a wide range of switching devices like circuit breakers, switches, switch fuse units, off-load isolators, HRC fuses, contactors, miniature circuit breakers, ELCBs, GFCIs etc. Switchgear and protection Equipments. Depending on operating and environmental conditions Metal-Enclosed Switchgear: This is an earthed metallic enclosure, made of supreme quality sheet steel that houses different types of circuit breakers. These devices play an essential role in the power system to protect the equipment from the heavy current. Therefore, additional care is taken during manufacturing of high voltage switchgear. Switchgear is often inspected using thermal imaging to assess the state of the system and predict failures before they occur. Just to mention before going into test, that low voltage switchgear and controlgear assemblies (Un ≤ 1000 V AC) may be use… Open air substations contain separately mounted and interconnected switching equipment and components, like current transformers (CTs), voltage transformers (VTs), busbar support insulators, cable sealing ends, etc., where atmospheric air provides the main insulation path to earth. This highly compressed gas bubble around the arc prevents re-striking of the arc after current reaches zero crossing of the cycle. Indoor switchgear can also be type tested for internal arc containment (e.g., IEC 62271-200). Transducers which require an external power source for their operation is called as a passive transducer. The switchgear refers to the collection of the switching devices required for a low, medium or high voltage electrical circuit. In an electric power system, switchgear is composed of electrical disconnect switches, fuses or circuit breakers used to control, protect and isolate electrical equipment. Whether to use switchgear, a switchboard, or both, depends largely on the design and requirements of the power system. The switching operation of the HV circuit is very rare. This led to a further improvement, because the switching and measuring devices could be attached to the front, while the wiring was on the back.[4]. However, such switchgear cannot be used profitably on a high voltage system.[5]. [1] The technology has been improved over time and can now be used with voltages up to 1,100 kV. A collection of one or more of these structures is called a switchgear line-up or assembly. From the typical light switch diagram, it controls one wire (pole) and it makes one connection (throw). When the user removes its finger from the button, contact of the pins are detached. Mechanical Switches. Definition: A device that is used to switch, control and protect the circuits as well as devices. Remote racking systems are available which allow an operator to rack switchgear from a remote location without the need to wear a protective arc flash hazard suit. In modern power systems, this is an essential device to protect the equipment from overload or short circuits. Although, switchgear are also classified on the basis of current rating, voltage class, operating methods, type of current, interrupting device, insulation tape, application and purpose. Substation, Its Function And Types An electrical sub-station is an assemblage of electrical components including busbars, switchgear, power transformers, auxiliaries etc. A protective relay detects any imbalance in currents, and trips circuit breakers to isolate the device. So these devices are essential to protect the equipment from the damage like a transformer, generators, lines, etc. Switchgears are as old as electricity generation. The switchgear is used for medium voltage applications. Of the types of distribution equipment described in the NFPA 70: National Electrical Code Article 408: Switchboards, Switchgear and Panelboards, switchgear is generally the most robustly constructed, the largest and the most expensive. This scheme was invented in Great Britain by Charles Hesterman Merz and Bernard Price.[7]. Low Voltage switchgear:. Switchgear and protection Equipments. They are. The tumbler switch with ordinary fuse is the simplest form of switchgear and was used to control and protect lights and other equipment in homes, offices etc. Switchgear is also used to enhance system availability by allowing more than one source to feed a load. Thus, this is all about an overview of switchgear. Switchgear for lower voltages may be entirely enclosed within a building. The earliest central power stations used simple open knife switches, mounted on insulating panels of marble or asbestos. To help ensure safe operation sequences of switchgear, trapped-key interlocking provides predefined scenarios of operation. This standard provides common rules that are recognized worldwide. [16], (German) Allgemeine Elektricitäts-Gesellschaft (ed). Types of Latch and Momentary Operation Switches Push Buttons Switch. The apparatus used for switching, controlling and protecting the electrical circuits and equipment is known as switchgear. Metal-Enclosed Switchgear: This is an earthed metallic enclosure, made of supreme quality sheet steel that houses different types … Breakers that use carbon dioxide as the insulating and arc extinguishing medium work on the same principles as a sulfur hexafluoride (SF6) breaker. The power system which deals above 36KV is called HV (high voltage) switchgear. To overcome this, a switchgear device is used because of its different features and functions. In normal conditions, it can operate manually so it ensures the safety of the operator & also proper electrical energy utilization. Oil-filled switchgear equipment allow arc energy to be contained and safely controlled. Switchgear working trend over time based on the maintenance adopted strategy Whatever support you need, both on and off-site, our teams have the necessary knowledge and experience. Download SGP Notes – 8. This device gives isolation to the circuits from power supplies. The consistent application of the modular principle both in electrical and mechanical design as well as the use of standardized components allows its flexible and compact design. This article will highlight some important things about switchgear. fuse in conjunction with a switch may serve the purpose of controlling and protecting the circuit. To see a good example of the various types of components found in medium voltage switchgear watch the illutrated video below on Siemens NXAir product. Basic Types of Switchgear Components Before learning about different switchgear components, let us understand what is switchgear. It helps to identify the faults and failure connections so that it can reduce the damage. IEEE Standard for Metal-Clad Switchgear. We are located across all five continents with service centers close to you. It includes switches, fuses, lightning arrestors,  Sectionalisers, Auto Reclosures, isolator/disconnect switch, CBS (circuit breakers). For voltages beyond 66 kV, we install outdoor switchgear equipment. Switchgear is used both to de-energize equipment to allow work to be done and to clear faults downstream. Other common types are oil or vacuum insulated switchgear. As the length of the sustainable arc is dependent on the available voltage, the elongated arc will eventually exhaust itself. 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