Recent Entries

  • Circuit analysis software

    With this software you will see over 80 examples of circuits analysis with help. Using help will give formula and steps for calculation.    Download
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  • Selecting of the MCCB

        The next step is selecting a breaker for use in an industrial control panel. In the following section we will focus on the MCCB for use as a feeder and as a branch circuit protective device.   Selecting The MCCB for Use as The Main Disconnect or  Feeder A typical industr...
  • General requirements for sizing conductors

        In this topic, we will look at the general requirements for sizing conductors once the calculated load current is known. This is a two-step process:   The first step is to look at the temperature rating of the terminals and the ampacity of the conductor that could be used ...
  • Short circuit calculation excel sheet

      With this excel sheet you will be able to calculate the short circuit in main feeders as well as branch circuit.     Download
  • Phase-to-earth faults

      Resistance-earthed neutral at A zero sequence generator is used for resistance-earthing.   Earth fault protection units (ANSI 51G) are installed on the feeders, incomer and zero   sequence generator.   Time-based discrimination is used between the different protectio...
  • Switchgear interlocking systems

      Interlocking between different switchgear apparatus and enclosure access covers and doors enhances personnel safety, as well as improving operational convenience. If a switching device can cause serious damage in an incorrect position, this must also have a locking facility.   Inter...
  • Static Transfer Switch

        Static Transfer Switch consists of two bidirectional thyristor switches equipped with control and protection system. The SSN (1-phase 2-poles) switch has an additional neutral line switch. Control system is based on the fail-safe CMOS logic. Input source and out-put line are protec...
  • Typical protective settings for motors

    Motor protection is used to prevent damage to the electrical motor, such as internal faults in the motor. Also external conditions when connecting to the power grid or during use have to be detected and abnormal conditions must  be prevented. Additionally, the protection relay prevents the di...
  • 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. ...