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  1. Jk1996

    Kw rating of a motor

    Thanks guys this has been interesting. So can I just clarify the kW rating on an isolator is equivalent to the motor name plate kW?
  2. Jk1996

    Kw rating of a motor

    So when sizing the isolator we can’t just use the Kw rating on the isolator and compare it to the motor nameplate?
  3. Jk1996

    Kw rating of a motor

    Thank you for your reply. I think I was getting confused as from what I believe a motor nameplate displays Kw ratings that are the mechanical output of the motor. The confusion then comes as the isolator is rated for the electrical power. Am I making sense?
  4. Jk1996

    Kw rating of a motor

    Hi, is the Kw rating on a motor mechanical output? I’m trying to get my head round if I can use a 7.5kw isolator for a 7.5kw motor?
  5. Jk1996

    Transformer short circuit secondary

    Hi I’m trying to understand the physics of a transformer with the secondary short circuited. When it’s shorted I’ve read something about the current decreasing in the secondary and rising in the primary what causes this?
  6. Jk1996

    22Kw motor isolator

    Thank you for your replies. So if it’s not being used to break the load the current is okay, the FLC of the motor is 40amp? This is temporary so ideally it should be labelled. What are your thoughts?
  7. Jk1996

    22Kw motor isolator

    I’ve got a temporary 22Kw motor running on a 63amp isolator. Think the isolator is rated AC3 for 11Kw . If the isolators not being used to switch the load is this okay?
  8. Jk1996

    Inductive circuits

    I’m really trying to understand this. How does the added resistance in the circuit effect the current?
  9. Jk1996

    Tensile testing

    I’m trying to answer a question relating to tensile testing and how the results from the test would differ from theoretical. I’m thinking temperature but I’m not sure if there is something more obvious I’m missing?
  10. Jk1996

    Inductive circuits

    But say if a motors voltage dropped from 415v across lines to 300v dues to something like a contactor fault would this not increase the impedance of the circuit (high resistance at contactor) so the current would be reduced?
  11. Jk1996

    motor cable

    So am I right in thinking for a motor circuit the fuse is purely for short circuit protection. Overloads on the cable will be protected by the overload set to 70Amps so the cable can be sized to the 70 amps not to 100amp?
  12. Jk1996

    Inductive circuits

    But what happens if voltage drops in all phases equally?
  13. Jk1996

    Inductive circuits

    I’ve been trying to understand inductive loads and voltage drop. I though if voltage drops on an inductive circuit the current will also decrease. Is this correct? I understand if on phase of a 3 phase motor circuit one phase is high resistance this causes an imbalance causing the other two...
  14. Jk1996

    three phase transformer

    Yes winding configuration?
  15. Jk1996

    three phase transformer

    hi guys I'm trying to get my head clear on transformer winding polarity on a three phase transformer. what are the effects of one winding having an incorrect polarity wrt the other 2. I know the phase relationship will change but physically what will happen? many thanks for your in-depth...
  16. Jk1996

    motor cable

    say if you have a motor circuit fed by 100amp fuses then then the overload set at 75 amps does this mean the motor cable should be rated for 100amps or should it be rated at 75amps?
  17. Jk1996

    Pure sine wave inverter

    Thank you guys, so what is the main reasons for worse or better efficiency?
  18. Jk1996

    Pure sine wave inverter

    What losses do we have in a pure sine wave inverter an I right in saying we’d have losses from the transistors. And from the internal transformer? I’m trying to work out what effects the efficiency of these.
  19. Jk1996

    Generator efficiency

    Thank you guys!!!
  20. Jk1996

    Generator efficiency

    Hi again guys I’m trying to get my head around the efficiency of generators. I’m looking at car alternator and can see this is an AC machine that then used a bridge rectifier to convert to DC this is where I’m thinking most of the efficiency is lost but want to understand in more depth?

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