400amps change over between existing 250kva genset and new 80kva genset

A interesting challenge!

You have an existing 250kVA genset that needs to be replaced with a new 80kVA genset, and you need to ensure a smooth transition (changeover) between the two. Since the new genset has a significantly lower capacity, you'll need to consider the following:

  1. Voltage: Both gensets are likely to produce the same voltage (e.g., 400V). This is a good starting point, as it simplifies the transition process.
  2. Current: The existing 250kVA genset produces approximately 400A (250kVA / 0.8 power factor), while the new 80kVA genset will produce around 200A (80kVA / 0.8 power factor). This is where the challenge lies.
  3. Changeover strategy: You'll need to design a changeover strategy that ensures a smooth transition between the two gensets. Here are a few options:
    • Parallel operation: Run both gensets in parallel for a short period to ensure the new genset is synchronized with the existing one. Then, gradually reduce the output of the existing genset and increase the output of the new genset.
    • Series operation: Run the existing genset in series with the new genset, allowing the new genset to take over gradually. This method is more complex and requires careful planning.
    • Automatic transfer switch (ATS): Install an ATS that can detect the output of both gensets and automatically switch between them. This is the most convenient option, but it may require additional hardware and programming.

To ensure a safe and successful changeover, consider the following:

Remember to always follow safety guidelines and consult with a qualified electrician or engineer if you're unsure about any aspect of the changeover process.