Motors

Discussion in 'Homework Help' started by Mikeelliott74, Jun 28, 2017.

  1. Mikeelliott74

    Thread Starter New Member

    Jun 28, 2017
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    Can anyone help please.

    The chief maintenance engineer has asked you to evaluate and compare the advantages and disadvantages of DC and 3-ph AC motors for two electrical installations in a new extension. The applications he wants you to consider for both types of motors are:

    a) A motor for 3 storey, 8 passenger lift

    b) The operation of fan motors in an air conditioning system
     
  2. MrChips

    Moderator

    Oct 2, 2009
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    1) Use a descriptive subject title other than "Motors". Think of how helpful your title is to readers.

    2) This is "Homework Help", not "We do your homework for you". Show your best effort at answering the question.
     
  3. Mikeelliott74

    Thread Starter New Member

    Jun 28, 2017
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    Thanks for the help
     
  4. MrChips

    Moderator

    Oct 2, 2009
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    You're welcome.
     
  5. Mikeelliott74

    Thread Starter New Member

    Jun 28, 2017
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    I will wait for someone that knows the answer........
     
  6. KeepItSimpleStupid

    AAC Fanatic!

    Mar 4, 2014
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    A) Hydraulic or cable?

    B) Condensor fan motors or air movers?
     
  7. Mikeelliott74

    Thread Starter New Member

    Jun 28, 2017
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    Cable and Condenser.
     
  8. KeepItSimpleStupid

    AAC Fanatic!

    Mar 4, 2014
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    What can a DC motor do that a 3 phase induction motor can't?
    For the DC motor, think "electric car" like even the Prius.
    For DC, there's the brushless DC motor.

    3 phase gives you higher cost with greater ____________.
     
  9. Mikeelliott74

    Thread Starter New Member

    Jun 28, 2017
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    Efficiency

    Do I mention VFD's
     
  10. KeepItSimpleStupid

    AAC Fanatic!

    Mar 4, 2014
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    A 3 phase motor is more reliable. No start capacitor, no extra start windings etc. Reliability is only there if 3 phase power is present and you haven't say, lost a phase. I think efficiency may depend on how loaded the motor is.

    A VFD is a good option for an air mover in duct work, but probably not for a condenser fan. ECM motors are now common in house furnaces because they can indirectly measure CFM and static pressure.
     
  11. Mikeelliott74

    Thread Starter New Member

    Jun 28, 2017
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    Thanks
     
  12. MaxHeadRoom

    Expert

    Jul 18, 2013
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    DC motors have generally been replaced by BLDC PM motors now due to reliability, also VFD's with 3ph motor with encoder feedback have been used in some applications that were typically used for elevator control etc.
    Max.
     
  13. Mikeelliott74

    Thread Starter New Member

    Jun 28, 2017
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    Thanks Max
     
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