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  1. Umtully1

    Plenum rated power cables

    Has anyone seen plenum rated power cables? I've got an electrical room with a 1000A feed thats right in the middle of a plenum space. My understanding of the NBCC is that all cables passing through the plenum space (which will be every cable leaving the electrical room) is required to be...
  2. Umtully1

    Surge Capacitor on Unit Transformer

    @Odlanor Not that I'm aware of, but then I wasn't specifically looking for one. Surge arrestors are common on almost all outdoor equipment though.
  3. Umtully1

    Surge Capacitor on Unit Transformer

    Ok, let me see if I understand the reasoning: The client would ask for a surge capacitor on the LV side of the GSU transformer, because there is the possibility, when the generator CB is open, that a lightning strike (or similar) surge event could cause the voltage surge to be transferred from...
  4. Umtully1

    Surge Capacitor on Unit Transformer

    Hi All, So I'm working on a generating station upgrade project and the utility has asked for surge capacitors on the low voltage side of the unit transformers. I've never seen this in my 4 shorts years of engineering, but neither has my mentor. Could anyone shed any light on why they're...
  5. Umtully1

    IEC 60909 - Short Circuit Calculations

    That makes sense. I kind of figured out that I"k was related to switchgear and MCCs, but its good to have confirmation. And you're right about the transformer hand calc, i used: Isc = KVA/(sqrt(3)*LV*%Z) And that would make sense that its a steady state value and furthermore that the...
  6. Umtully1

    IEC 60909 - Short Circuit Calculations

    I know there's going to be a decaying DC offset. What I don't know is how ip relates to my equipment rating.
  7. Umtully1

    IEC 60909 - Short Circuit Calculations

    I've got a question regarding IEC 60909. Can someone explain how the different fault levels, ip, I"k, and Ik relate to different pieces of equipment. Specifically in relation to MCC, variable frequency drives and transformers? I've gone through the standard and understand how those three...
  8. Umtully1

    Large Motor starts on Generators

    Thanks for the help, I should've posted some more details. Being relativily new to motor starts, I've been told that synchronous motors start uncoupled from the load, and once they're up to speed they close a clutch, so that answers one question. We're also planning on using a reduced voltage...
  9. Umtully1

    Large Motor starts on Generators

    Hi I was hoping someone could point me in the direction of some literature or advice regarding starting large motors on generators only? We have a very weak grid, only 1 18MVA generator and we want to start a 2000hp synchronous motor. Our plan is use a couple smallish diesel gensets as...

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