compressor motor tripping breaker

Discussion in 'Home Repair' started by a, Aug 13, 2004.

  1. a

    a Guest

    I have an older model electric motor driven compressor that causes my
    electrical circuit breaker to trip when the motor kicks in to "refill" a low
    pressurized tank. In other words, when the tank is empty and I plug it in,
    it starts and works fine, filling up the tank, then stops automatically when
    full. After use or when the tank's pressure becomes low, the motor attempts
    to start the compressor again, but is not able to. The motor hums for a
    short while, then trips the breaker.

    The circuit is one a 15 amp breaker, the motor draws less than 11 amps. Any
    ideas?
    a, Aug 13, 2004
    #1
    1. Advertising

  2. "a" <> wrote in message news:UpUSc.13229$fz2.1992@edtnps89...
    > I have an older model electric motor driven compressor that causes my
    > electrical circuit breaker to trip when the motor kicks in to "refill" a

    low
    > pressurized tank. In other words, when the tank is empty and I plug it

    in,
    > it starts and works fine, filling up the tank, then stops automatically

    when
    > full. After use or when the tank's pressure becomes low, the motor

    attempts
    > to start the compressor again, but is not able to. The motor hums for a
    > short while, then trips the breaker.
    >
    > The circuit is one a 15 amp breaker, the motor draws less than 11 amps.

    Any
    > ideas?


    Have you really checked the motor draw? It can be substantially higher at
    start-up than in a steady state situation. I experienced breaker trips for
    years in the exact same situation with my compressor. My solution was to
    run a dedicated circuit to the shop for the compressor. I think I used a 25
    or 30 amp breaker and sized the wire appropriately.

    KB
    Kyle Boatright, Aug 13, 2004
    #2
    1. Advertising

  3. "Greg O" <> wrote in message
    news:...
    >
    > "a" <> wrote in message news:UpUSc.13229$fz2.1992@edtnps89...
    > > I have an older model electric motor driven compressor that causes my
    > > electrical circuit breaker to trip when the motor kicks in to "refill" a

    > low
    > > pressurized tank. In other words, when the tank is empty and I plug it

    > in,
    > > it starts and works fine, filling up the tank, then stops automatically

    > when
    > > full. After use or when the tank's pressure becomes low, the motor

    > attempts
    > > to start the compressor again, but is not able to. The motor hums for a
    > > short while, then trips the breaker.
    > >
    > > The circuit is one a 15 amp breaker, the motor draws less than 11 amps.

    > Any
    > > ideas?
    > >
    > >

    >
    > On all compressors there is some sort of unloader that releases the air
    > pressure at the head or discharge of the compressor pump. My bet is your
    > compressor's unloader has failed, and does not dump the air at shut off.
    > Some units have this unloader tied in to the pressure switch, others use a
    > valve at the tank that looks like a plain old fitting.
    > Greg
    >


    Ditto.

    The function of the unloader being so the motor doesnt start under
    load--allows it to get up to speed before having to do any serious work, as
    motor startup draws a buncha amperage as is.

    Oftentimes the unloader valve gets clogged with crud from the compressor oil
    and simply need cleaning in solvent of some type.

    Usually a properly functioning unloader will release a small amount of air
    each time the pump cycles off and it makes a short hissing sound at this
    time.

    --

    SVL
    PrecisionMachinisT, Aug 13, 2004
    #3
  4. "PrecisionMachinisT" <> wrote in message
    news:...
    >
    > "Greg O" <> wrote in message
    > news:...
    > >
    > > "a" <> wrote in message news:UpUSc.13229$fz2.1992@edtnps89...
    > > > I have an older model electric motor driven compressor that causes my
    > > > electrical circuit breaker to trip when the motor kicks in to "refill"

    a
    > > low
    > > > pressurized tank. In other words, when the tank is empty and I plug

    it
    > > in,
    > > > it starts and works fine, filling up the tank, then stops

    automatically
    > > when
    > > > full. After use or when the tank's pressure becomes low, the motor

    > > attempts
    > > > to start the compressor again, but is not able to. The motor hums for

    a
    > > > short while, then trips the breaker.
    > > >
    > > > The circuit is one a 15 amp breaker, the motor draws less than 11

    amps.
    > > Any
    > > > ideas?
    > > >
    > > >

    > >
    > > On all compressors there is some sort of unloader that releases the air
    > > pressure at the head or discharge of the compressor pump. My bet is your
    > > compressor's unloader has failed, and does not dump the air at shut off.
    > > Some units have this unloader tied in to the pressure switch, others use

    a
    > > valve at the tank that looks like a plain old fitting.
    > > Greg
    > >

    >
    > Ditto.
    >
    > The function of the unloader being so the motor doesnt start under
    > load--allows it to get up to speed before having to do any serious work,

    as
    > motor startup draws a buncha amperage as is.
    >
    > Oftentimes the unloader valve gets clogged with crud from the compressor

    oil
    > and simply need cleaning in solvent of some type.
    >
    > Usually a properly functioning unloader will release a small amount of air
    > each time the pump cycles off and it makes a short hissing sound at this
    > time.
    >
    > --
    >
    > SVL
    >


    warning: thread hijack for another compressor question

    i also have one that has a problem. it will go on, charge up the tank to 125
    psi and shutoff correctly. however, the relief valve under the electronics
    will then open, vent to 75psi, close, and the motor will go on again.

    there is another safety release valve screwed into the top of the tank. that
    one isn't the one that lets go.

    is this also a failure in the unloader? there's a plug in the top that has 2
    tubes coming out of it. one goes to the motor, one to the valve that's
    giving me the problem. does this plug have some sort of diaphragm that could
    be bad? the schematic i have of the compressor doesn't even have this part
    listed, so i don't know what it does.

    thanks,
    charlie
    Charles Spitzer, Aug 13, 2004
    #4
  5. "Greg O" <> wrote in message
    news:...
    >
    > "Charles Spitzer" <> wrote in message
    > news:cfilfc$pdq$...
    > >
    > > > >

    > >
    > > warning: thread hijack for another compressor question
    > >
    > > i also have one that has a problem. it will go on, charge up the tank to

    > 125
    > > psi and shutoff correctly. however, the relief valve under the

    electronics
    > > will then open, vent to 75psi, close, and the motor will go on again.
    > >
    > > there is another safety release valve screwed into the top of the tank.

    > that
    > > one isn't the one that lets go.
    > >
    > > is this also a failure in the unloader? there's a plug in the top that

    has
    > 2
    > > tubes coming out of it. one goes to the motor, one to the valve that's
    > > giving me the problem. does this plug have some sort of diaphragm that

    > could
    > > be bad? the schematic i have of the compressor doesn't even have this

    part
    > > listed, so i don't know what it does.
    > >
    > > thanks,
    > > charlie
    > >
    > >

    > With the unloader that is controlled by the pressure switch, there is a
    > one-way cheack valve in the compressor discharge line, before the line
    > enters the tank. Your check valve is stuck open. The function of the check
    > valve is to stop air from leaveing the tank, flowing back through the
    > discharge line, when the unloader is working.
    > Greg
    >

    thanks. any idea where it could be, or if it can be fixed? what would it
    look like? there's no check valve on my parts list.

    regards,
    charlie
    Charles Spitzer, Aug 13, 2004
    #5
  6. a

    m Ransley Guest

    Unloader or not a motor on a compressor can take 9x surge on an old
    worn motor- compressor. Test your surge laod, wires etc.
    m Ransley, Aug 13, 2004
    #6
  7. "Greg O" <> wrote in message
    news:...
    >
    > "Charles Spitzer" <> wrote in message
    > news:cfjd9m$s2o$...
    > >
    > > "Greg O" <> wrote in message
    > > news:...
    > > >
    > > > "Charles Spitzer" <> wrote in

    message
    > > > news:cfilfc$pdq$...
    > > > >
    > > > > > >
    > > > >
    > > > > warning: thread hijack for another compressor question
    > > > >
    > > > > i also have one that has a problem. it will go on, charge up the

    tank
    > to
    > > > 125
    > > > > psi and shutoff correctly. however, the relief valve under the

    > > electronics
    > > > > will then open, vent to 75psi, close, and the motor will go on

    again.
    > > > >
    > > > > there is another safety release valve screwed into the top of the

    > tank.
    > > > that
    > > > > one isn't the one that lets go.
    > > > >
    > > > > is this also a failure in the unloader? there's a plug in the top

    that
    > > has
    > > > 2
    > > > > tubes coming out of it. one goes to the motor, one to the valve

    that's
    > > > > giving me the problem. does this plug have some sort of diaphragm

    that
    > > > could
    > > > > be bad? the schematic i have of the compressor doesn't even have

    this
    > > part
    > > > > listed, so i don't know what it does.
    > > > >
    > > > > thanks,
    > > > > charlie
    > > > >
    > > > >
    > > > With the unloader that is controlled by the pressure switch, there is

    a
    > > > one-way cheack valve in the compressor discharge line, before the line
    > > > enters the tank. Your check valve is stuck open. The function of the

    > check
    > > > valve is to stop air from leaveing the tank, flowing back through the
    > > > discharge line, when the unloader is working.
    > > > Greg
    > > >

    > > thanks. any idea where it could be, or if it can be fixed? what would it
    > > look like? there's no check valve on my parts list.
    > >
    > > regards,
    > > charlie
    > >
    > >

    >
    > What brand of compressor?
    > My guess it would be right where the pump discharge line enters the tank.
    > Greg
    >


    Agreed.

    Probly a brass plug looking thing screwed into the top of the tank, 1in pipe
    threads or so usually--the compresser generally delivers air to it through
    copper or aluminum tubing.

    --

    SVL
    PrecisionMachinisT, Aug 14, 2004
    #7
  8. a

    Guest

    It could be you have a weak breaker. Swap it with another one in the
    box (of the same amperage), or just buy another one and try. At most
    you'll be out the cost of the breaker, usually around $5, and you'll
    have a spare breaker. Motors consume huge amounts of power during
    startup. most breakers allow for that. Your breaker may just not be
    able to handle it. You could also have a weak/dying capacitor in the
    motor.


    On Fri, 13 Aug 2004 01:01:40 GMT, "a" <> wrote:

    >I have an older model electric motor driven compressor that causes my
    >electrical circuit breaker to trip when the motor kicks in to "refill" a low
    >pressurized tank. In other words, when the tank is empty and I plug it in,
    >it starts and works fine, filling up the tank, then stops automatically when
    >full. After use or when the tank's pressure becomes low, the motor attempts
    >to start the compressor again, but is not able to. The motor hums for a
    >short while, then trips the breaker.
    >
    >The circuit is one a 15 amp breaker, the motor draws less than 11 amps. Any
    >ideas?
    >
    , Aug 14, 2004
    #8
  9. a

    DanG Guest

    The problem is with the compressor.

    It is either the unloader or the back check valve, more likely
    the back check (on some compressors the same piece performs both
    functions). This part is located where the compressor discharge
    line enters the tank on many units. Your compressor is trying to
    start against the pressure in the tank for which it was never
    designed.

    ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^
    Keep the whole world singing . . . .
    DanG (remove the sevens)




    "PrecisionMachinisT" <> wrote in
    message news:...
    >
    > "Greg O" <> wrote in message
    > news:...
    > >
    > > "a" <> wrote in message

    news:UpUSc.13229$fz2.1992@edtnps89...
    > > > I have an older model electric motor driven compressor that

    causes my
    > > > electrical circuit breaker to trip when the motor kicks in

    to "refill" a
    > > low
    > > > pressurized tank. In other words, when the tank is empty

    and I plug it
    > > in,
    > > > it starts and works fine, filling up the tank, then stops

    automatically
    > > when
    > > > full. After use or when the tank's pressure becomes low,

    the motor
    > > attempts
    > > > to start the compressor again, but is not able to. The

    motor hums for a
    > > > short while, then trips the breaker.
    > > >
    > > > The circuit is one a 15 amp breaker, the motor draws less

    than 11 amps.
    > > Any
    > > > ideas?
    > > >
    > > >

    > >
    > > On all compressors there is some sort of unloader that

    releases the air
    > > pressure at the head or discharge of the compressor pump. My

    bet is your
    > > compressor's unloader has failed, and does not dump the air at

    shut off.
    > > Some units have this unloader tied in to the pressure switch,

    others use a
    > > valve at the tank that looks like a plain old fitting.
    > > Greg
    > >

    >
    > Ditto.
    >
    > The function of the unloader being so the motor doesnt start

    under
    > load--allows it to get up to speed before having to do any

    serious work, as
    > motor startup draws a buncha amperage as is.
    >
    > Oftentimes the unloader valve gets clogged with crud from the

    compressor oil
    > and simply need cleaning in solvent of some type.
    >
    > Usually a properly functioning unloader will release a small

    amount of air
    > each time the pump cycles off and it makes a short hissing sound

    at this
    > time.
    >
    > --
    >
    > SVL
    >
    >
    DanG, Aug 14, 2004
    #9
  10. "PrecisionMachinisT" <> wrote in message news:<>...
    > "Greg O" <> wrote in message
    > news:...
    > >
    > > "Charles Spitzer" <> wrote in message
    > > news:cfjd9m$s2o$...
    > > >
    > > > "Greg O" <> wrote in message
    > > > news:...
    > > > >
    > > > > "Charles Spitzer" <> wrote in

    > message
    > > > > news:cfilfc$pdq$...
    > > > > >
    > > > > > > >
    > > > > >
    > > > > > warning: thread hijack for another compressor question
    > > > > >
    > > > > > i also have one that has a problem. it will go on, charge up the

    > tank
    > to
    > 125
    > > > > > psi and shutoff correctly. however, the relief valve under the

    > electronics
    > > > > > will then open, vent to 75psi, close, and the motor will go on

    > again.
    > > > > >
    > > > > > there is another safety release valve screwed into the top of the

    > tank.
    > that
    > > > > > one isn't the one that lets go.
    > > > > >
    > > > > > is this also a failure in the unloader? there's a plug in the top

    > that
    > has
    > 2
    > > > > > tubes coming out of it. one goes to the motor, one to the valve

    > that's
    > > > > > giving me the problem. does this plug have some sort of diaphragm

    > that
    > could
    > > > > > be bad? the schematic i have of the compressor doesn't even have

    > this
    > part
    > > > > > listed, so i don't know what it does.
    > > > > >
    > > > > > thanks,
    > > > > > charlie
    > > > > >
    > > > > >
    > > > > With the unloader that is controlled by the pressure switch, there is

    > a
    > > > > one-way cheack valve in the compressor discharge line, before the line
    > > > > enters the tank. Your check valve is stuck open. The function of the

    > check
    > > > > valve is to stop air from leaveing the tank, flowing back through the
    > > > > discharge line, when the unloader is working.
    > > > > Greg
    > > > >
    > > > thanks. any idea where it could be, or if it can be fixed? what would it
    > > > look like? there's no check valve on my parts list.
    > > >
    > > > regards,
    > > > charlie
    > > >
    > > >

    > >
    > > What brand of compressor?
    > > My guess it would be right where the pump discharge line enters the tank.
    > > Greg
    > >

    >
    > Agreed.
    >
    > Probly a brass plug looking thing screwed into the top of the tank, 1in pipe
    > threads or so usually--the compresser generally delivers air to it through
    > copper or aluminum tubing.


    http://www.harborfreight.com/cpi/ctaf/displayitem.taf?Itemnumber=47065

    there is a plug screwed into the top of the tank on the side that
    isn't visible in this picture. however, that part isn't listed in the
    parts list that came with it, so i don't know if it's orderable. is
    this fixable, or jury-riggable with another check valve?
    Charlie Spitzer, Aug 16, 2004
    #10
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