Recent Entries

  • Earth fault on MV and HV network

        LV earth fault means very small hv overcurrent Earth fault level tends to remain constant   Generally, MV systems are impedance earthed at its neutral end, which limits the earth fault current to around 300 A. Figure  shows the current distribution for an MV earth faul...
  • solar elevation triangles for PV System

    We need to know a few things first:   Module width (assuming landscape mounting orientation): 40 inches for this example.   Module tilt angle: we will use 30 degrees for this example.   Time of day and year we wish to have no shading: we will use 9 a.m.–3 p.m. ...
  • Advantages of Underground Cables vs Overhead Lines

      Advantages of Underground Cables vs Overhead Lines   There are a number of advantages associated with undergrounding of the transmission line across the development which include the following: Reduced visual impact by removing tower No. 11 in the centre of the development and th...
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  • Protection Against Fire Substation

        with fire associated with power transformers or oil-filled reactors, where the consequences can be particularly serious and extensive because of the large volume of oil that can catch fire and spread widely (Fig). For more details on protection against fire   ...
  • Buchholz relay

      The Buchholz relay is a gas operated relay used for the protection of oil immersed transformers against all the types of internal faults. It is named after its inventor, Buchholz. The slow developing faults called incipient faults in the transformer tank below oil level operate Buchholz re...
  • Coordination Procedure

        Step 1 – The Generator Owner determines the proper undervoltage trip set point for his machine. This should be based on the manufacturer’s recommendation or protection application circumstances for the generating station. Step 2 – The Transmission Owner...
  • Electrical Network schemes

      Single radial network This is the simplest, least costly network scheme and the one with least overall reliability. The single radial scheme for a net-work with several voltage levels has a tree structure, possibly with backbones which supply the loads distributed along the route.   ...
  • Power Fuses

    Power fuses, shown in Figure  in a typical transformer protective application, provide protection that is both reliable and economical. They are inexpensive—both in   The operating procedure for power fuses is straightforward. Typically, after a fuse has operated, the load-side c...
  • Response of a CT in saturated state

      The emergence of static relays leads to revision of protection behaviour as a whole in the case of strong currents: as the CT saturates beyond a certain threshold, the first reaction is often to avoid this by raising the threshold. However, this results in both additional costs (more effic...
  • Factors Affecting Transmission System Losses

    The following is a description of major factors that can affect transmission losses for a system.   Metering Data   Accurate metering of loads, generation, and transmission interties is critical to reconcile load-flow analysis to determine transmission losses. Some utilities are usin...