Power consumption of 1/10 HP motor.

Discussion in 'Electrical Engineering' started by RFI-EMI-GUY, Jun 18, 2008.

  1. RFI-EMI-GUY

    RFI-EMI-GUY Guest

    Can anyone comment the power consumption of this motor? Is this at all
    typical. The application is a 800 CFM attic fan.

    "1.2.2 Motor: 1/10th HP, thermally protected shaded pole type, 1100 RPM,
    3.4 AMPS." - used at 115 VAC - 391 VA

    My concern is not with peak load, but typical consumption when running
    in that application. By comparison I measured my 1/2 HP rated air
    handler motor at 3.0 Amps 230 VAC. 690 VA

    Given that this is 1/5 the motor as the one used in my airhandler I
    would expect it to consume only about 138 VA or 1.2 A at 115 VAC.

    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
    RFI-EMI-GUY, Jun 18, 2008
    #1
  2. RFI-EMI-GUY

    James Sweet Guest

    RFI-EMI-GUY wrote:
    > Can anyone comment the power consumption of this motor? Is this at all
    > typical. The application is a 800 CFM attic fan.
    >
    > "1.2.2 Motor: 1/10th HP, thermally protected shaded pole type, 1100
    > RPM, 3.4 AMPS." - used at 115 VAC - 391 VA
    >
    > My concern is not with peak load, but typical consumption when running
    > in that application. By comparison I measured my 1/2 HP rated air
    > handler motor at 3.0 Amps 230 VAC. 690 VA
    >
    > Given that this is 1/5 the motor as the one used in my airhandler I
    > would expect it to consume only about 138 VA or 1.2 A at 115 VAC.
    >



    You need to know the power factor in order to get a meaningful number
    here, it may only be around 0.5. One of those $20 Kill A Watt devices is
    perfectly adequate for measuring the true power consumption.

    Shaded pole motors are not very efficient, you'll notice they tend to
    run very hot. Still, without knowing the actual load or the power factor
    you're flying blind and anything is just a guess, but it's easy to measure.
    James Sweet, Jun 18, 2008
    #2
  3. RFI-EMI-GUY

    RFI-EMI-GUY Guest

    James Sweet wrote:
    >
    > RFI-EMI-GUY wrote:
    >> Can anyone comment the power consumption of this motor? Is this at all
    >> typical. The application is a 800 CFM attic fan.
    >>
    >> "1.2.2 Motor: 1/10th HP, thermally protected shaded pole type, 1100
    >> RPM, 3.4 AMPS." - used at 115 VAC - 391 VA
    >>
    >> My concern is not with peak load, but typical consumption when running
    >> in that application. By comparison I measured my 1/2 HP rated air
    >> handler motor at 3.0 Amps 230 VAC. 690 VA
    >>
    >> Given that this is 1/5 the motor as the one used in my airhandler I
    >> would expect it to consume only about 138 VA or 1.2 A at 115 VAC.
    >>

    >
    >
    > You need to know the power factor in order to get a meaningful number
    > here, it may only be around 0.5. One of those $20 Kill A Watt devices is
    > perfectly adequate for measuring the true power consumption.
    >
    > Shaded pole motors are not very efficient, you'll notice they tend to
    > run very hot. Still, without knowing the actual load or the power factor
    > you're flying blind and anything is just a guess, but it's easy to measure.


    True but I have neither the motor or a Kill A Watt meter on hand.



    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
    RFI-EMI-GUY, Jun 18, 2008
    #3
  4. RFI-EMI-GUY

    RFI-EMI-GUY Guest

    Salmon Egg wrote:
    > In article <AsY5k.16835$8q2.2690@trnddc02>,
    > James Sweet <> wrote:
    >
    >> RFI-EMI-GUY wrote:
    >>> Can anyone comment the power consumption of this motor? Is this at all
    >>> typical. The application is a 800 CFM attic fan.
    >>>
    >>> "1.2.2 Motor: 1/10th HP, thermally protected shaded pole type, 1100
    >>> RPM, 3.4 AMPS." - used at 115 VAC - 391 VA
    >>>
    >>> My concern is not with peak load, but typical consumption when running
    >>> in that application. By comparison I measured my 1/2 HP rated air
    >>> handler motor at 3.0 Amps 230 VAC. 690 VA
    >>>
    >>> Given that this is 1/5 the motor as the one used in my airhandler I
    >>> would expect it to consume only about 138 VA or 1.2 A at 115 VAC.
    >>>

    >>
    >> You need to know the power factor in order to get a meaningful number
    >> here, it may only be around 0.5. One of those $20 Kill A Watt devices is
    >> perfectly adequate for measuring the true power consumption.
    >>
    >> Shaded pole motors are not very efficient, you'll notice they tend to
    >> run very hot. Still, without knowing the actual load or the power factor
    >> you're flying blind and anything is just a guess, but it's easy to measure.

    >
    > 1/10 HP is only about 75W. Obviously, the power factor and most likely
    > the efficiency is going to be piss poor. How much did this thing cost?
    > My guess is that any price is too high for what you are getting.
    >
    > Bill


    The 3.4 amp specs are typical for attic exhaust fans. Should I assume
    that the nameplate current draw is "locked rotor" value provided in case
    someone decides to install 5 of these on one 15 amp circuit?

    I am only interested in what the motor normally draws while running. If
    two of these fans require nearly 800 watts to exhaust and cool my attic,
    I am concerned. If its only 300 watts I am less concerned. Does anyone
    have a ballpark on this?

    --
    Joe Leikhim K4SAT
    "The RFI-EMI-GUY"©

    "Treason doth never prosper: what's the reason?
    For if it prosper, none dare call it treason."

    "Follow The Money" ;-P
    RFI-EMI-GUY, Jun 18, 2008
    #4
  5. RFI-EMI-GUY

    James Sweet Guest

    RFI-EMI-GUY wrote:
    > Salmon Egg wrote:
    >> In article <AsY5k.16835$8q2.2690@trnddc02>,
    >> James Sweet <> wrote:
    >>
    >>> RFI-EMI-GUY wrote:
    >>>> Can anyone comment the power consumption of this motor? Is this at
    >>>> all typical. The application is a 800 CFM attic fan.
    >>>>
    >>>> "1.2.2 Motor: 1/10th HP, thermally protected shaded pole type,
    >>>> 1100 RPM, 3.4 AMPS." - used at 115 VAC - 391 VA
    >>>>
    >>>> My concern is not with peak load, but typical consumption when
    >>>> running in that application. By comparison I measured my 1/2 HP
    >>>> rated air handler motor at 3.0 Amps 230 VAC. 690 VA
    >>>>
    >>>> Given that this is 1/5 the motor as the one used in my airhandler I
    >>>> would expect it to consume only about 138 VA or 1.2 A at 115 VAC.
    >>>>
    >>>
    >>> You need to know the power factor in order to get a meaningful number
    >>> here, it may only be around 0.5. One of those $20 Kill A Watt devices
    >>> is perfectly adequate for measuring the true power consumption.
    >>>
    >>> Shaded pole motors are not very efficient, you'll notice they tend to
    >>> run very hot. Still, without knowing the actual load or the power
    >>> factor you're flying blind and anything is just a guess, but it's
    >>> easy to measure.

    >>
    >> 1/10 HP is only about 75W. Obviously, the power factor and most likely
    >> the efficiency is going to be piss poor. How much did this thing cost?
    >> My guess is that any price is too high for what you are getting.
    >>
    >> Bill

    >
    > The 3.4 amp specs are typical for attic exhaust fans. Should I assume
    > that the nameplate current draw is "locked rotor" value provided in case
    > someone decides to install 5 of these on one 15 amp circuit?
    >
    > I am only interested in what the motor normally draws while running. If
    > two of these fans require nearly 800 watts to exhaust and cool my attic,
    > I am concerned. If its only 300 watts I am less concerned. Does anyone
    > have a ballpark on this?
    >



    I would guess about 140W, but that's only a guess. The power factor if
    uncorrected is probably only about 0.5, so the VA will be around double
    what the wattage is, and the label is for worst case conditions. In the
    real world, the fan is probably not pushing the motor to produce its max
    rated horsepower.
    James Sweet, Jun 18, 2008
    #5

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