Gas Insulated Switchgear (GIS) are very useful in urban applications where there are space limitations and installing conventional switchgear components is not possible. GIS has full functionality of a switchyard, and consists of a compact array of all important protection components like Incomer, Bus, Line isolators, earthing switches, CBs, CTs and PTs, etc. GIS are installed in city buildings, on roofs, on offshore platforms, industrial plants, and hydroelectric power stations. These devices switch off an electrical circuit in case of an over current or short circuit condition occurring downstream. If a GIS fails to operate or operates incorrectly under these fault conditions, it can cause severe damage to itself and to the equipment connected to it. This can result in huge revenue losses due to outages on the transmission lines.
In many cases, the GIS may be standing still for a number of years without operating. But, when an abnormal condition occurs, it needs to operate within a few milliseconds to isolate the fault and protect the system.
GIS has a very compact design with all the electrical components of the switchgear enclosed in a gas-tight enclosure filled with SF6 gas. It contains a number of moving parts that are working in close coordination that require periodic inspection and maintenance to ensure that they operate reliably when required. Contact timings, contact bounce, non-simultaneity of contacts, contact travel and speed measurements, current and voltage characteristics, static and dynamic contact resistance, insulation tests, endurance tests, etc. are some of the tests performed on GIS. However, in addition to the above tests, gas pressure measurements are also critical for GIS, as any gas leakage could prove devastating to the GIS operation.
Crest manufactures a full range of GIS testing products for OEMs for ensuring the quality of the product before delivery and for end users to ensure optimum performance of their assets.