Preferred three-phase grounding applications on wood pole structures using grounding cluster bars are shown in figures 1 and 2. Grounding cluster bars must be positioned just below the lowest elevation of the lineman’s feet for the work zone (approximately the elevation of the phase conductors) and shall be bonded to the pole structure ground leads …
Improve power transfer with shunt capacitor banks
Shunt capacitor banks are used to an increasing extent at all voltage levels. There are a variety of reasons for this like the growing need for power transfer on existing lines while avoiding transfer of reactive power, better use of existing power systems, improving voltage stability, right-of-way and cost problems, voltage control and compensation of …
HGI generator circuit breaker – ABB
Application The circuit-breakers type HGI can be used as generator circuit-breaker in all types of power plants with unit sizes between 60 – 180 MVA and nominal voltages up to 21kV. If used as feeder breakers in industry plants, the nominal voltage can be up to 24kV. The breakers are also suited for retrofit or …
MiCOM P139 – Feeder Management and Bay Control
MiCOM P139 is a cost-effective one-box solution for integrated numerical time-overcurrent protection and control. The unit’s protection functions provide selective short-circuit protection, ground fault protection and overload protection in medium- and high voltage systems. The systems can be operated as solidlygrounded, low-impedance-grounded, resonantgrounded or isolated-neutral systems. The multitude of protection functions incorporated into the unit …
Economics of GIS
The equipment cost of GIS is naturally higher than that of AIS due to the grounded metal enclosure, the provision of an LCC, and the high degree of factory assembly. A GIS is less expensive to install than an AIS. The site development costs for a GIS will be much lower than for an AIS …
Transients – Line Disturbances
Lightning strikes and switching transients on power lines will propagate down the line and eventually arrive at a substation. There, the voltage will be clamped by lightning arresters to a level the substation equipment can handle without damage. This voltage will be passed on to the distribution lines in two forms: differential and common modes. …
Gas-Insulated Transmission Line – GIL
The gas-insulated transmission line (GIL) is a system for the transmission of electricity at high power ratings over long distances. In cases where overhead lines are not possible, the GIL is a viable technical solution to bring the power transmitted by an overhead line underground without a reduction of power transmission capacity. As a gas-insulated …
SF6 gas as insulating and arc-quenching medium
Sulphur hexafluoride gas (SF6) is employed as insulation in all parts of the installation, and in the circuit-breaker also for arc-quenching. SF6 is an electronegative gas, its dielectric strength at atmospheric pressure is approximately three times that of air. It is incombustible, non-toxic, odourless, chemically inert with arc-quenching properties 3 to 4 times better than …
Use Of Vacuum As A Breaking Medium
SF6 and vacuum are the two most modern breaking techniques in the fields of Medium Voltage (from 1 to 52 kV) and High Voltage (> 72.5 kV). They appeared in the 1960’s and rapidly developed as of the 1970’s. Today they have replaced the former air and oil breaking techniques (see fig. 1). Whereas SF6 …
Basics Of Subtransmission Systems
Subtransmission systems are those circuits that supply distribution substations. Several different subtransmission systems can supply distribution substations. Common subtransmission voltages include 34.5, 69, 115, and 138 kV. Higher voltage subtransmission lines can carry more power with less losses over greater distances. Distribution circuits are occasionally supplied by high-voltage transmission lines such as 230 kV; such …
