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Thread: Generators and well pumps

  1. #16
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by VAWellDriller View Post
    It was 2 wire, and I didn't catch the starting amps, but it was running at 9.8 ... I started it multiple times with no problem. You should; as I think you mentioned before, turn the eco throttle off... I tried it once just to see, and though it worked, it didn't like it much. With a warm gen and eco turned off, it doesn't sound like much of a strain on the gen at all, I would easily rely on this for water.

    With that reading, That motor has about a 50% loss of power, or more.

    Harmonics off of a inverter, can throw off the reading of a amp meter.


    Can you close the outlet of the pump and get a reading, Just for Fun ?


    I want to play. lol
    Theory only works perfect in a vacuum.

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  2. #17
    DIY Member Arky217's Avatar
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    Quote Originally Posted by valveman View Post
    It is the capacitor in the control box that “kicks” the motor harder, so the gen set doesn’t have to do it, which keeps the starting amps lower.

    The smaller wire limits how much current you can send to the motor, so is decreases the starting amperage.

    With a capacitor start, small wire, and starting against a closed valve, the starting amps may not be much more than the running amps.

    Thanks VAWellDriller for the quick reply !

    To Valveman,

    On your quote above, what you said seems logical, but could you explain how that ties in to the data on the following 2 pumps ?

    Pump #1, Goulds 2 wire, model# 5GS05421C, 1/2 hp, 115v.
    The electrical data shows full load amps 7.9, Service Factor amps 9.8, Locked Rotor amps 28

    Pump #2, Goulds 3 wire, model# 5GS05411CL, 1/2 hp, 115v.
    The electrical data shows full load amps 'Y=8.8', 'B=8.8', 'R=0', service factor amps 'Y=10.9', 'B=10.9', 'R=0',
    Locked Rotor amps 44

    On the 3 wire under the general description, it just shows amps as 11.0, but on the electrical data chart it gets into
    these Y, B, R figures. I don't know what that means.
    I got the above data off of the Goulds electrical data for these two pumps.


    Could you explain in a little more detail how the 3 wire setup results in a lesser start current.
    ( I'm just curious, since the data shows such a diffenence in the locked rotor current between the 2 wire and 3 wire (28 vs 44).

    Thanks,
    Arky

  3. #18
    DIY Senior Member VAWellDriller's Avatar
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    Quote Originally Posted by DonL View Post
    With that reading, That motor has about a 50% loss of power, or more.

    Harmonics off of a inverter, can throw off the reading of a amp meter.


    Can you close the outlet of the pump and get a reading, Just for Fun ?


    I want to play. lol
    Really bored today and I guess you sparked my interest; so I re-tested with pressure gauge and 1" water meter.
    I'm not at all following you with the statement about 50% power loss or more??? And also not at all following you on the inverter throwing off the amp readings.

    Here's what I got:

    9.8 amp, wide open, 16 gpm
    9.2 amp, 60 psi on pump, 10 gpm
    6.6 amp, 103 psi deadhead pressure.

    Repeated this test with shop power and got results within +/- 0.1 amps.

    As I see it, the motor was right on for the manufacturers nameplate amp draw, and the wet end was pretty close on the pump curve (actually high on the deadhead) and a little low on flow at 60 psi. This pump is about 5 years old and was pulled out to install higher flow pump for the customer.

  4. #19
    DIY Member Arky217's Avatar
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    Quote Originally Posted by DonL View Post
    With that reading, That motor has about a 50% loss of power, or more.

    Harmonics off of a inverter, can throw off the reading of a amp meter.


    Can you close the outlet of the pump and get a reading, Just for Fun ?


    I want to play. lol

    DonL, Are you saying that the motor is not developing the full 1/2 hp at the 9.8 amps ?

    From the Goulds Electrical Data, the FLA of that motor is 7.9

    Does that mean that running the pump from the generator will be detrimental to the motor ?

    Also, about overload protection for the motor on submersible pumps; is it built into the motor somehow, like a thermal switch, or should overload protection be added to the circuit ?

    Thanks,
    Arky

  5. #20
    In the Trades Texas Wellman's Avatar
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    This thread has been very informative. I always wanted to know if the EU2000i would run the 1/2 HP 115V motors.

    FWIW I am told that the Franklin 2-wire and the Centri-pro 2-wire are not similar. Supposedly the Centi-pro has a start-cap built into the motor whereas the Franklin has the biac-switch. The franklin manual clearly states that the 2-wire uses 2x the power to start via a generator.

    PM sent on where to get a grundfos for a great price.

  6. #21
    DIY Senior Member VAWellDriller's Avatar
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    Still bored, going home after this....looked at Centri-pro book harder....This motor is listed as having full load amps of 7.9 and efficiency of 42%, and service factor amps of 9.8 with efficiency of 54%; maybe Don is smart enough to know that a 1/2 hp isn't very efficient if it draws 9.8 amps; I don't know that much about motor efficiency buy apparently he's right that it's losing about 50%; important point here is that it is performing as designed by Centripro, and operating within their ratings.

    I think that you have absolutely nothing to worry about running this motor on your Honda....it performed exactly the same for me with mine and on shop power. As far as overloads, the motor has a thermal overload built in, and you have the overload on the generator, so I don't think you need anything else.

  7. #22
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by Arky217 View Post
    DonL, Are you saying that the motor is not developing the full 1/2 hp at the 9.8 amps ?

    From the Goulds Electrical Data, the FLA of that motor is 7.9

    Does that mean that running the pump from the generator will be detrimental to the motor ?

    Also, about overload protection for the motor on submersible pumps; is it built into the motor somehow, like a thermal switch, or should overload protection be added to the circuit ?

    Thanks,
    Arky

    No, The Motor may even be producing more than 1/2 hp. Best to under rate than over rate.

    1/2 HP is equal to about 372 watts, That is at 100 percent efficiency, and could only happen in a vacuum, then maybe not. You will never see 100% efficiency.

    9.8 amps at 120V is about 1.5 HP, of power being used to run a 1/2 HP pump. So 1 HP is wasted, or 745 watts. 6.2 amps wasted, making heat. That is why pumps get Hot.

    The Generator losses have to be in the equation also. As far as I can tell the motor on your generator is a about 4 HP, running on good fuel.

    Most inverters generators operate at around 80% efficiency, or less. That is why a 4HP motor can only make 2000 Watts of Output power, If even that much in the real world. That is why you use more than 2980 watts of power to make 2000.

    Are you confused yet ?. I hope I got my math correct, in all of that mess.

    I am not a very good explainer,(Yes New word that I invented) But I hope you understand.

    Sounds like VAWellDriller made some nice test today. Big thanks to him.

    A good Extra protection for your pump, would be a 10 amp breaker, or a 10 amp Ceramic fuse, like used in Microwave Ovens.


    VAWellDriller has been Playing and proving data for real world test, And I hope getting paid for it. Very nice work.


    Have Fun.
    Last edited by DonL; 01-29-2014 at 12:20 PM.
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  8. #23
    In the Trades Texas Wellman's Avatar
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    What Don is saying I think is that the 1/2 HP refers to the output power of the shaft, not the input power to the motor in the form of electricity.

    Another reason I like the Grundfos SQ is because it uses permanent magnets in the motor. A regular induction run motor uses some of the electricity to generate it's magnetic field, causing the efficiency that Don is talking about to be lower. The grundfos may be 1/2 HP but it will use less electricity to generate 1/2 HP at the shaft.

  9. #24
    DIY Senior Member VAWellDriller's Avatar
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    Quote Originally Posted by Texas Wellman View Post
    This thread has been very informative. I always wanted to know if the EU2000i would run the 1/2 HP 115V motors.

    FWIW I am told that the Franklin 2-wire and the Centri-pro 2-wire are not similar. Supposedly the Centi-pro has a start-cap built into the motor whereas the Franklin has the biac-switch. The franklin manual clearly states that the 2-wire uses 2x the power to start via a generator.

    PM sent on where to get a grundfos for a great price.
    HA -- I guess now you'll want me to try it with a Franklin?

  10. #25
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by Texas Wellman View Post
    What Don is saying I think is that the 1/2 HP refers to the output power of the shaft, not the input power to the motor in the form of electricity.

    Another reason I like the Grundfos SQ is because it uses permanent magnets in the motor. A regular induction run motor uses some of the electricity to generate it's magnetic field, causing the efficiency that Don is talking about to be lower. The grundfos may be 1/2 HP but it will use less electricity to generate 1/2 HP at the shaft.

    The only problem with permanent magnet motors is that they will normally have Brushes, and run on DC. More parts to go bad.

    AC is converted to dc in the pump , But they can run at higher, and variable RPM.
    Theory only works perfect in a vacuum.

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  11. #26
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by VAWellDriller View Post
    HA -- I guess now you'll want me to try it with a Franklin?

    If you have one. you should do it.

    I love getting paid to play.
    Theory only works perfect in a vacuum.

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  12. #27
    In the Trades Texas Wellman's Avatar
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    The motors I use do not have brushes, they are brushless.

  13. #28
    Moderator valveman's Avatar
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    Quote Originally Posted by Texas Wellman View Post
    The franklin manual clearly states that the 2-wire uses 2x the power to start via a generator.
    Yeah I don’t understand the locked rotor amps being twice as much for a 3 wire with a control box, because I know it takes twice as much to start a 2 wire motor.

    Quote Originally Posted by VAWellDriller View Post
    Still bored, going home after this....looked at Centri-pro book harder....This motor is listed as having full load amps of 7.9 and efficiency of 42%, and service factor amps of 9.8 with efficiency of 54%; maybe Don is smart enough to know that a 1/2 hp isn't very efficient if it draws 9.8 amps; I don't know that much about motor efficiency buy apparently he's right that it's losing about 50 %.
    Don is right, 4” submersibles do good to get up in the high 50% for efficiency. I think that is way they don’t publish efficiency charts for 4” pumps. I believe it is the small diameter of the impellers that lessens the efficiency.

    Quote Originally Posted by VAWellDriller View Post
    Here's what I got:

    9.8 amp, wide open, 16 gpm
    9.2 amp, 60 psi on pump, 10 gpm
    6.6 amp, 103 psi deadhead pressure.
    Good to know that the Goulds 10 GPM impeller will reduce the amp draw by 33% when the pump is restricted to low flow. Pentair 10 GPM pumps don’t drop in amps at all, but Grundfos 10 GPM drops almost 50%.

    Quote Originally Posted by DonL View Post
    Harmonics off of a inverter, can throw off the reading of a amp meter.
    An inverter actually pulses out a 60 hertz radio frequency instead of a smooth sinusoidal wave as from a regular generator. You really need an RMS meter to get an accurate reading from an inverter, but it is probably close enough.

    The harmonic content of the power from an inverter actually increases the motor heat as opposed to a sinusoidal wave. The voltage spikes from an inverter can be 4 times the line voltage. But when you start at 115V, the spikes will usually be less than 500 volts, and the motor is probably made to withstand 600 volt spikes. A low voltage motor doesn’t suffer from inverter voltage spikes nearly as bad as a 480 volt system. But inverters do shorten the life of motor windings.

    Quote Originally Posted by DonL View Post
    The only problem with permanent magnet motors is that they will normally have Brushes, and run on DC. More parts to go bad.

    AC is converted to dc in the pump , But they can run at higher, and variable RPM.
    I think most permanent magnet motors now use a Hall sensor instead of brushes. This has been a big advance in motor technology, but there are still problem with permanent magnets. I don’t think the magnetism is really permanent?

    Quote Originally Posted by Texas Wellman View Post
    This thread has been very informative.
    I agree! Thanks to everyone for the info!

  14. #29
    Jack of all trades DonL's Avatar
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    Quote Originally Posted by Texas Wellman View Post
    The motors I use do not have brushes, they are brushless.

    That is good. I can see where Not having a Field winding could save power.

    I would guess them motors would have a Soft Start to bring them up to speed slow.

    Less surge current can let you use smaller wire.

    Some of the PWM motors can cause RFI, I take it that they use PWM, but not really sure on the models you use.


    Are the pumps that you use high RPM models, that use PWM ?
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  15. #30
    In the Trades Texas Wellman's Avatar
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    Yes, the Grundfos SQ have a soft-start.

    I'm guessing that PWM = pulse width modulation? I have no idea if they are PWM. You plug them in, they work LOL.

    Quote Originally Posted by DonL View Post
    That is good. I can see where Not having a Field winding could save power.

    I would guess them motors would have a Soft Start to bring them up to speed slow.

    Less surge current can let you use smaller wire.

    Some of the PWM motors can cause RFI, I take it that they use PWM, but not really sure on the models you use.


    Are the pumps that you use high RPM models, that use PWM ?

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