it can be set for max four enclosures at min intervals of 10 sec and instantaneous protection can be suppressed after the first reclosure so that persistent faults are referred to time graded protection. It is an attracted armature type relay. Capacitor units for the higher distribution voltages and those connected to conductors energized at transmission voltages are normally mounted on open-type racks. These relays use a permanent magnet or parts with a high remittance to remain the armature at the same point as the coil is electrified when the coil power source is taken away. High speed biased differential relay An instantaneous phase or earth fault protection and for definite time operation when used with a timer. It is used to serve the following three purposes. Optional equipment that may be added to the substation transformer is tap changing equipment. this is a non-directional relay with a definite minimum time which has an adjustable inverse time/current characteristics. Earthing switches are usually associated and interlocked with disconnectors and mounted on the same base frame. This allows up to 10 faults clearance before initiating an alarm. The substation buses are current-carrying devices that interconnect the individual pieces of substation equipment. Underground and overhead conduits and control wire are installed to connect the controls of all the equipment in the substation to the control panels normally installed in the control house. Often, a fourth single-phase transformer will be located at the substation to serve as a spare. Lightning arresters contain semiconductor blocks, which limit the magnitude of high-surge voltages, permit the large-surge currents to pass harmlessly to the ground, and interrupt the power-follow current after the surge is eliminated. Power transformers are the most important equipment in an electrical substation. according to application targets such as transmission In the past, it’s difficult to re-install the protection or control relay by a different manufacturer, to avoid the log-off the communication with the substation control system. The transmission substation transformers support the transmission system and the smaller sub-transmission and distribution substation transformers. The lightning arresters are installed in a substation near the termination of aerial circuits and close to the more valuable pieces of equipment, such as power transformers. Tell us what you're thinking... we care about your opinion! A substation performs a major role in our power system. For over 100 years, Hitachi ABB Power Grids has been keeping substations safe and secure, with protective relays and breakers connected over bulletproof telecommunications. Metal-oxide surge arresters function like a ceramic capacitor at normal line voltage, limiting the flow of current to ground. Zone indication VAA51, CAG12 and VAA31. not possible with fuses and circuit breakers. It has two pair of contacts. It is necessary to use dc control systems with a storage battery as a source to make it possible to operate equipment during periods of system disturbances and outage. Air Insulated Switchgear Substation, as the name suggests, utilizes primary substation equipment whose terminals are in the air. (This adopts a conventional air-insulated way of busbar connection to GIS. Stage 3: At this point, the problem has occurred and caused damage. Almost all Gas Insulated Switchgear substations are built indoor. The dc line or network connects with one (or more) other conversion stations. This CDG 11-type relay is applied for selective phase and earth fault protection in time graded systems for AC machines. Sort by: relevance - date. The faulted circuit is switched out of service automatically and de-energized, protecting the remaining portion of the transmission network from trouble. The fuses are connected in series with the power transformer that serves as a source for the switchgear. According to IEEE, Circuit Switcher is a mechanical switching device with an integral interrupter, suitable for making, carrying, and interrupting currents under normal circuit conditions. Today D-relays are used in its millions across the world. The circuit switcher has the following benefits over circuit breaker: Compact, low cost, and some models include a visible break switch in their operation. The alarm is followed by lockout if selected no. It produces an alternating current (AC) in its secondary which is proportional to the AC current in its primary. The DMH type relay provides high speed biased differential protection for two or three winding transformers. At voltages above about 100 kV (phase) the conventional electromagnetic type of potential transformer becomes expensive owing to insulation requirements. The shorter time setting is provided by a passing contact and longer time setting by the final contact. Protection Relay Substation jobs in Ontario. Lightning arrester (Surge Diverter) The device or equipment used for the protection of the power system against voltage surge is called “surge diverter” or “lightning arrester”. Use this relay with an SV merging unit to provide complete substation bay control with high-speed breaker protection and simplified settings in one economical system. c) VAR 42 giving four reclosure. Disconnectors are not designed to break fault current although some designs will make fault current. The protection relay can be parameterized and controlled from … The contacts of the circuit breakers are opened and closed by mechanical linkages manufactured from insulating materials and utilizing energy from compressed air, electric magnets, or charged springs. Get access to premium HV/MV/LV technical articles, electrical engineering guides, research studies and much more! So just as motor protection relay is common, so are phase monitoring relay applications. This chapter considers the combination of relays required to protect various items of power system equipment, plus a brief reference to the diagrams that are part of substation design work. The CDD type relays are applied for directional or earth fault protection of ring mains, parallel transformers or parallel feeders with the time graded principle. The shunt reactor shown in the figure is a three-phase single-winding transformer which serves as an inductive reactance on the power system, thus neutralizing the capacitive reactance associated with the long extra-high-voltage transmission line. this scheme consists of the following relays, XCG22-3 for phase to phase and 3 for phase to ground, YCG17, mho starting unit one in each place, VAT51 along with timing unit for zone 2 and 3, 86-X aux. Drawbacks over a circuit breaker include low-speed reclosing, and not designed for high-operation environments. Some relays are used to supervise, monitor, and perform predetermined operations as required by system conditions. Circuit Switchers are different from the circuit breakers. Relays automatically operate their contacts to properly identify the source of trouble and remove it from the electrical system. The substations contain power transformers that reduce the voltage from sub-transmission levels to distribution levels, usually in the range of 4.16Y/2.4 kV to 34.5Y/19.92 kV. Transmission, Sub transmission and distribution substation, Electric substations with equipment used to convert high-voltage, extra-high-voltage (EHV), or ultra-high-voltage (UHV) transmission lines to the intermediate voltage sub-transmission lines or to switch sub-transmission circuits operating at voltages in the range of 34.5 kV to 161 kV are referred to as, Substations located in the middle of a load area are called, The transformers are normally equipped to regulate the substation bus voltage. In this article you will learn different types of substations, their functions and different equipment used used in them. Secondly with tapped interposing transformers for use with standard line current transformers of any ratio. The use of a circuit switcher in place of fuses is a major improvement in protection. They perform different functions. The capacity of the transmission substation transformers will normally be in the range of 1,000 MVA to 50 MVA. The voltages will generally be in the range of 161,000 volts to 4,160 volts and the capacities in the range of 50 MVA to 5 MVA. This arrangement avoids the need for separate post insulators for the earth switch and often simplifies interlocking. The PGD relay is a high speed induction cup unit used to give directional properties to three phase IDMT over-current relays, for the protection of parallel feeders, inter connected networks and parallel transformers against phase to phase and three phase faults. They are different from distribution transformers. They are used to. Displayed here are job ads that match your query. Special attention has been paid to the differential protection and over current protection of these transformers, which has been used in this substation presently. The substation bus tubing (or bus bar) is aluminum or copper. Complete and Innovative solution for Transformer Bays and other Machines IDV Relays include all Protection, Control and Measurement functions for Two or Three Winding transformers or autotransformers at any voltage level, with Single or Double Breaker. If one of the transformers connected in the bank fails, the spare is energized to expedite the restoration of electric service.