Recent Entries

  • Protective conductors, PEN conductors and equipotential bonding

      Requirements as specified by VDE 0100 Part 540 The following may be used as protective conductors: – conductors in multicore cables and wires, – insulated or bare conductors in the same covering together with phase conductors and the neutral conductor, e.g. in pipes or electr...
  • Medium voltage switchgear cubicle types

        The medium voltage switchgear consists of the following cubicle types: Incoming feeder (circuit-breaker) cubicle. Standard design with cable connections from the front at the bottom (options for cable connections from the rear at the bottom). Outgoing feeder (circuit-breaker) c...
  • Circuit breaker vs Fuse

      Circuit breaker. A circuit breaker is a mechanical device for making and breaking an electrical circuit under all conditions. Switch. A switch is a device for making and breaking a circuit which is carrying a current not greatly in excess of normal loading. Isolator. An isolator is a means...
  • Low voltage switchboard

    A distribution switchboard is the point at which an incoming-power supply divides into separate circuits, each of which is controlled and protected by the fuses or switchgear of the switchboard. A distribution switchboard is divided into a number of functional units, each comprising all the electr...
  • Disconnectors (Isolators)

      A disconnector is a device consisting of moving contacts that are mechanically closed to close the electrical circuit to other devices or mechanically open so that it can detach part of the adjacent grid through proximity and along the path. Provide disconnection. This allows the conn...
  • Pump Motor Starting

    Various methods are utilized to accelerate the generator/motor in the pump direction during starting (IEEE, 1010). These include the following: Full voltage, across the line starting—Used primarily on smaller units, the unit breaker is closed and the unit is started as an induction genera...
  • Rule of Parallel Circuits

      In a parallel circuit, there are as many independent currents as there are branches, in the same way that in a series circuit, there are as many independent voltages as the number of components. Independent is used, because there are also currents that are dependent on the other currents and...
  • Electrical Safety at Work and Safety Rules

      We work for our living. Therefore work must not endanger our lives nor must it harm the workers, but accidents always happen. As a professional individual when working with electricity, we must avoid any unsafe conditions by following the safety rules. Something that one must always c...
  • All possible faults in a three-phase a-c system

    A minimum of three overcurrent relays and a total  of  three current transformers is required to detect all possible faults in a three-phase a-c system. Two of the relays are usually connected in the phase circuits and the third relay     is usually connected in the r...
  • Electrical cables in the substation

    As regards the cables, in substations we can have the following situations: – accessible sub-panel compartment, or a walkable basement under the supporting plane of the switchgear, for which a net height of not less than 1.7 m is recommended. This solution is suitable for cases where the ca...