Maintenance of GIS: Experience has shown that the internal parts of Gas Insulated Substation are so well protected inside the metal enclosure that they do not age and as a result of proper material selection and lubricants, there is negligible wear of the switch contacts. Only the circuit breaker arcing contacts and the Teflon nozzle of the interrupter experience wear proportional to the number of operations and the level of the load or fault currents being interrupted. Good contact and Read More …
Installation, Operation and Interlocks For GIS
Installation: The GIS is usually installed on a monolithic concrete pad or the floor of a building. It is most often rigidly attached by bolting and/or welding the GIS support frames to embedded steel plates or beams. Chemical drill anchors can also be used. Expansion drill anchors are not recommended because dynamic loads may loosen expansion anchors when the circuit breaker operates. Large GIS installations may need bus expansion joints between various sections of the GIS to adjust to the Read More …
Electrical and Physical Arrangement, Grounding, Testing For GIS
Electrical and Physical Arrangement: For any electrical one-line diagram there are usually several possible physical arrangements. The shape of the site for the GIS and the nature of connecting lines and/or cables should be considered. Figure 1 compares a “natural” physical arrangement for a breaker and a half GIS with a “linear” arrangement. Most GIS designs were developed initially for a double bus, single breaker arrangement Figure 2. This widely used approach provides good reliability, simple operation, easy protective relaying, Read More …
Gas Monitor System, Compartments and Zones for GIS
Gas Monitor System: The insulating and interrupting capability of the SF6 gas depends on the density of the SF6 gas being at a minimum level established by design tests. The pressure of the SF6 gas varies with temperature, so a mechanical temperature-compensated pressure switch is used to monitor the equivalent of gas density. GIS is filled with SF to a density far enough above the minimum density for full dielectric and interrupting capability so that from 10 to 20% of Read More …
Surge Arrester and Control System for GIS
Surge Arrester: Zinc oxide surge arrester elements suitable for immersion in SF6 are supported by an insulating cylinder inside a GIS enclosure section to make a surge arrester for overvoltage. Because the GIS conductors are inside in a grounded metal enclosure, the only way for lightning impulse voltages to enter is through the connections of the GIS to the rest of the electrical system. Cable and direct transformer connections are not subject to lightning strikes, so only at SF6-to-air bushing Read More …
Bus and Air, Cable, Direct Transformer Connection For GIS
Bus: To connect GIS modules that are not directly connected to each other, an SF6 bus consisting of an inner conductor and outer enclosure is used. Support insulators, sliding electrical contacts, and flanged enclosure joints are usually the same as for the GIS modules. Air Connection: SF6-to-air bushings are made by attaching a hollow insulating cylinder to a flange on the end of a GIS enclosure. The insulating cylinder contains pressurized SF6 on the inside and is suitable for exposure Read More …
Circuit Breaker, Current And Voltage Transformers, Disconnect And Ground Switches For GIS
Circuit Breaker: GIS uses essentially the same dead tank SF6 puffer circuit breakers used in AIS. Instead of SF6 -to-air as connections into the substation as a whole, the nozzles on the circuit breaker enclosure are directly connected to the adjacent GIS module. Current Transformers: CTs are inductive ring types installed either inside the GIS enclosure or outside the GIS enclosure. The GIS conductor is the single turn primary for the CT. CTs inside the enclosure must be shielded from Read More …
Construction and Service Life of GIS Substation
GIS is assembled of standard equipment modules (circuit breaker, current transformers, voltage transformers, disconnect and ground switches, interconnecting bus, surge arresters, and connections to the rest of the electric power system) to match the electrical one-line diagram of the substation. A cross-section view of a 242-kV GIS shows the construction and typical dimensions. Construction of GIS Substation: The modules are joined using bolted flanges with an “O” ring seal system for the enclosure and a sliding plug-in contact for the Read More …
Ten Crazy Trends In The Smart Home Industry
Smart home technology is sweeping across the nation as rapidly as a field fire. Not only that, it is changing the world at the same time. Here are 10 trends in the smart home industry making a huge impact on people’s lives!. 1. Demand For Voice Control 72% of smart home device owners want voice control capability. It’s one of the easiest ways to automate a home. But voice control capability comes at a high price. Interestingly enough this demand Read More …
GIS – Gas Insulated Substations
A gas-insulated substation (GIS) uses a superior dielectric gas, SF6, at moderate pressure for phase-to-phase and phase-to ground insulation. The high voltage conductors, circuit breaker interrupters, switches, current transformers, and voltage transformers are in SF6 gas inside grounded metal enclosures. The atmospheric air insulation used in a conventional, air-insulated substation (AIS) requires meters of air insulation to do what SF6 can do in centimeters. GIS can therefore be smaller than AIS by up to a factor of 10. A GIS Read More …