Sizing start & run capacitors for 100hp 3 Phase motor - Page 2
Close
Login to Your Account
Page 2 of 4 FirstFirst 1234 LastLast
Results 21 to 40 of 73
  1. #21
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    Quote Originally Posted by dalmatiangirl61 View Post
    What are you trying to run that requires 50Hp?

    I'm going to play psychic and say I see a large generator in your future
    The 50HP load is a part of a hydraulic system. I've looked into generators but there are a few downsides that I'd like to avoid; mostly burning diesel and the nox they create. Secondly is the price of running those machines.

  2. #22
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    Quote Originally Posted by rons View Post
    There are published papers on line that discuss large converters for stuff like farm equipment. The circuits don't look anything like that little Fitch.
    If you just are beginning like Bill S. mentions and you have already looked at the big picture and this is what you want, then I think a pony motor is
    what you need. And that won't be too bad.
    Would a pony motor eliminate the inrush current from starting the 100HP idler?

  3. #23
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,793
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8635

    Default

    Quote Originally Posted by newbea View Post
    Would a pony motor eliminate the inrush current from starting the 100HP idler?
    Not ALL of it, no. Most of it, yes. Not to forget an AC pony is itself also a part of the overall power budget. IC engine or DC off battery bank are possible, though uncommon.

    In larger sizes there is still the issue of whether the idler is dropped onto the line more or less already "in sync" or NOT.

    A combination of pony plus some form of "soft" start is still better than an "operating Engineer" monitoring syncrosopes or such to try to catch it at the least contrarian time.

    Then there is the open question as to how much of that 50 HP will be demanded in actual use?

    To the extent that - once past its starting inrush - it is itself partially an "idler" it needs less idler HP in its RPC.

    There is more than one figure of merit in the cited listing for the Phase-A-Matic delivery of 100 HP by use of paired 50 HP.

    Not only is each easier to start, for lighter loads only ONE may need to be online at all. Or BOTH online for starting a heavy load, then one dropped off the line for a lighter running load and lower waste.

    Three by 30 HP, or a 75 + 25 HP, or any of several other combinations of primary and supplementary idlers - might be of use vs a single 100 HP for your load as well?

    Share the nature of that load, get more appropriate advice.

  4. #24
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    Quote Originally Posted by hanermo View Post
    Lots of good advice, imho.

    To OP:
    Since You seem to have sufficient power to run 100 HP, most of the inrush current problems and scares mentioned are probably non-issues, if You just have any kind of resistor/limiter on the power lines in the rpc.
    To limit the sub-second peak power in and out.

    One good option is old-fashioned light bulbs for smaller loads, or perhaps water heater resistors for larger loads.
    A say 2 kW nominal resistor for a water heater can typically take 10x for less than a second, as that is what they do 24x7, in use.
    Maybe 20x, or 40 kW peak, 500 ms or so.
    And you can parallel them, and they are very cheap.
    Gang 3, done.

    Resistors for heating, and light bulbs, take huge power for tiny periods, until they heat up, and start to work near their rated range.
    They act as large shunts reducing shock loads.

    As most-all said, the pony motor is probably the right way to go for 3-phase startup at 100 hp output.

    One point:
    Does the 100 Hp load come up at startup, at 100% ?
    Mining conveyors, water lifts, might do this.

    But maybe 4/5 or 80% of normal use cases might not need 100% capacity at startup.
    A tiny 2 kW motor can start a 75 kW motor, at no-load.

    --
    Highly recommend double-insulated cables for the setup.
    Highly recommend a couple of dumb analog thermometers glued here and there.
    A measuring/peaking USB volt/amp tester left in place for a few weeks is a good idea.

    Power company demand charges / peak reserve pricing / whatever might easily be reduced by 200$ per month, once You understand your needs, use, and actual peaks.
    And a pony motor, or clever electronics, might also drop your demand charges by 200$/month, maybe more.
    Depending, details.
    The power should be no issue as I've said 600v 300amp;
    The tip about the resistor sounds interesting. I would prefer to buy the 2Kw resistor since it's simpler to maintain. Adding the resistor between the two legs leading into the RPC.

    I am definitely considering the pony motor; this idler motor is rated at 1160RPM, I could use a smaller motor to spin it up and then just flip the current to the Idler. Would using the pony motor along with the resistor reduce/ eliminate that inrush current?

    The 100HP will come online unloaded so a 2Kw motor could definitely do the job of starting this 100HP Idler.
    The 50HP load will be a part of a hydraulic system; The hydraulic pump starts unloaded as well.

    I do have a few analog ammeters and voltmeters both on the line in and each phase going out.

  5. #25
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    I was trying to calculate just how much inrush current this particular 100HP motor will pull on startup.

    There is no reference code such as A; I did notice it's marked as AEED; this a teco motor;

    Type Code: AEED / AEEDWA TOP
    Low Voltage Squirrel Cage Motors

    Output 75~250HP (55KW~185kw)
    Pole (Speed) 2 ~ 8
    Voltage 200V, 220V, 346V, 380V, 400V, 415V, 440V
    Frequency (Hz) 50, 60
    Frame Size 280SA~315MC
    Protection Enclosure IP 44

    Design Standards: IEC, JEC, CNS
    Environment: non-hazardous, outdoor service for AEEDWA.
    Stator insulation: Class F Insulation

    I know the motor that I have is;
    100HP
    1160RPM
    220/440v
    236/118amps
    75KW

    I am using the formula
    motor-full-load-current-calculator_1.gif

    from jcalc

    According to the calculation using
    220v
    3PH
    75kW
    .86 power factor
    .80 efficiency

    this motor will draw 286 amp inrush at startup. Does those calculations look right?

    Would a pony motor reduce/ eliminate this startup inrush current?

  6. #26
    Join Date
    May 2011
    Country
    UNITED STATES
    State/Province
    New Jersey
    Posts
    2,301
    Post Thanks / Like
    Likes (Given)
    204
    Likes (Received)
    1257

    Default

    What power source do you ultimately wish to run this setup on?

  7. #27
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    Quote Originally Posted by plastikdreams View Post
    What power source do you ultimately wish to run this setup on?
    about 300 x 310 watts solar panels giving 93kW

  8. #28
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,793
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8635

    Default

    Quote Originally Posted by newbea View Post
    I was trying to calculate just how much inrush current this particular 100HP motor will pull on startup.

    There is no reference code such as A; I did notice it's marked as AEED; this a teco motor;

    Type Code: AEED / AEEDWA TOP
    Low Voltage Squirrel Cage Motors

    Output 75~250HP (55KW~185kw)
    Pole (Speed) 2 ~ 8
    Voltage 200V, 220V, 346V, 380V, 400V, 415V, 440V
    Frequency (Hz) 50, 60
    Frame Size 280SA~315MC
    Protection Enclosure IP 44

    Design Standards: IEC, JEC, CNS
    Environment: non-hazardous, outdoor service for AEEDWA.
    Stator insulation: Class F Insulation

    I know the motor that I have is;
    100HP
    1160RPM
    220/440v
    236/118amps
    75KW

    I am using the formula
    motor-full-load-current-calculator_1.gif

    from jcalc

    According to the calculation using
    220v
    3PH
    75kW
    .86 power factor
    .80 efficiency

    this motor will draw 286 amp inrush at startup. Does those calculations look right?

    Would a pony motor reduce/ eliminate this startup inrush current?
    Only 286 A inrush for a 236 A *run* looks under by around a full order of magnitude to me. Mind - appropriate protective gear handles motor starting all the time. It is mercifully SHORT before tapering off very rapidly.

    And you really should be going the extra mile to run it off 440 VAC, not 220, same again your 50 HP load-motor, and for several sound reasons, pennies-for-Copper not the reverse surely on that list.

    Don't let yourself become so thoroughly "married" to this one 100 HP motor as a cheap or so-called "free" solution if it comes a poor fit after all.

    That thinking can end up making the whole project cost more than the alleged "savings".

  9. #29
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    Quote Originally Posted by thermite View Post
    Only 286 A inrush for a 236 A *run* looks under by around a full order of magnitude to me. Mind - appropriate protective gear handles motor starting all the time. It is mercifully SHORT before tapering off very rapidly.

    And you really should be going the extra mile to run it off 440 VAC, not 220, same again your 50 HP load-motor, and for several sound reasons, pennies-for-Copper not the reverse surely on that list.

    Don't let yourself become so thoroughly "married" to this one 100 HP motor as a cheap or so-called "free" solution if it comes a poor fit after all.

    That thinking can end up making the whole project cost more than the alleged "savings".
    It's not really about the costs per se. I am worried about long term reliability. It is a solar project that will be unmanned for long periods of time.

    I can take the 110 and step it up to 440 if necessary. The wattage isn't the problem. It's a turn on and forget system. The idler runs continuously; The load runs periodically.

    I can't do that with a generator without someone going out there to refuel; solar can along with batteries can.

    Trying not to derail this topic I am trying to run the tests in a controlled environment and then test in the field.

    It really is about the reliability.

  10. #30
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,793
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8635

    Default

    Quote Originally Posted by newbea View Post
    It's not really about the costs per se. I am worried about long term reliability. It is a solar project that will be unmanned for long periods of time.

    I can take the 110 and step it up to 440 if necessary. The wattage isn't the problem. It's a turn on and forget system. The idler runs continuously; The load runs periodically.

    I can't do that with a generator without someone going out there to refuel; solar can along with batteries can.
    Sounds to me like a better fit to a bespoke VFD or inverter, or even a TEAM of less concentrated powered ones. For-sure remote monitoring and control as well as local sensors, timers, and the like.

    ELSE one of the Phase-Perfect line as are aimed directly at unattended deep wells and irrigation system pumps and positioning motive power.

    RPC are durable, but also more wasteful, percentage-wise when they are NOT part of a balanced load UNDER load and working close to the point for which they were balanced. Nature of the beast.

  11. Likes TDegenhart liked this post
  12. #31
    Join Date
    Feb 2004
    Location
    peekskill, NY
    Posts
    24,477
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    4576

    Default

    Quote Originally Posted by thermite View Post
    In larger sizes there is still the issue of whether the idler is dropped onto the line more or less already "in sync" or NOT.
    .....
    Because there are no rotor currents until the one winding is energized, I've never seen anyone worry about powering
    up an idler motor "in sync." What would be in, or out of, sync with?

    Also I am having a bit of a tough time understanding the voltage that will be provided. At one point it was 600 volts.
    Then the discussion was revolving around 120 volts, 240, or 480. Which is it?

    The inrush current that was calculated might have been with the system fed from 440, which would almost be about right,
    it was around 2X the running current I think.

    Photovoltaics provide dc, what kind of inverters are being used? Wouldn't it be a darn sight easier to set the inverters up to
    simply supply three phase power from the git-go, and eliminate the need for an idler and all the associated fooferwaw
    that goes with it?

  13. Likes JST, TDegenhart liked this post
  14. #32
    Join Date
    Mar 2006
    Location
    Auburn CA
    Posts
    435
    Post Thanks / Like
    Likes (Given)
    5
    Likes (Received)
    39

    Default

    For the input power, you must multiply the three phase current by approximately 5/3
    to account for the same power from a single phase circuit. I don't think you did that.

  15. #33
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,040
    Post Thanks / Like
    Likes (Given)
    1892
    Likes (Received)
    3044

    Default

    Quote Originally Posted by jim rozen View Post
    Because there are no rotor currents until the one winding is energized, I've never seen anyone worry about powering
    up an idler motor "in sync." What would be in, or out of, sync with?

    .....?
    With no balance capacitors, there will be minimal voltage/ current and no issue. If there are balance capacitors connected, they will provide exciting current assuming there is some residual magnetism in the iron to generate rotor currents during spin-up. That can load the pony, and also may have a sync issue.

    Answer, is "don't do that".

  16. #34
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,793
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8635

    Default

    Quote Originally Posted by JST View Post
    With no balance capacitors, there will be minimal voltage/ current and no issue. If there are balance capacitors connected, they will provide exciting current assuming there is some residual magnetism in the iron to generate rotor currents during spin-up. That can load the pony, and also may have a sync issue.

    Answer, is "don't do that".
    Spot-on.

    And PM has seen the effects reported arredy - de minimus, small idlers, not so "innocent" serious-large ones that even benefit from pony-start.

    Solar? Battery pile?

    Surely 3-Phase inverters make sense "off grid", fifty-hoss load motor.

    Grid-tie, single-phase? Might be a whole 'nuther kettle of electrons, but still possible to do-up a bilingual rig saner than a 100 hoss RPC.

    Idler is durable enuf. Contactors, primary, soft-start, and load.. remoting of monitoring and control is... whatever it is.

    Not necessarily an iota better than for decent inverters. This gear ain't "bleeding edge" for long years already. Utilities know what works, and for how long it can be trusted both as to maintenance type and intervals, and total life-cycle-wise.

    Either way, that ain't no "trivial residential" size installation, so it's worth more Engineering than but a notch or so above "hobby grade" guesswork gleaned off the indifferent internet.

  17. #35
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    Quote Originally Posted by jim rozen View Post
    Because there are no rotor currents until the one winding is energized, I've never seen anyone worry about powering
    up an idler motor "in sync." What would be in, or out of, sync with?

    Also I am having a bit of a tough time understanding the voltage that will be provided. At one point it was 600 volts.
    Then the discussion was revolving around 120 volts, 240, or 480. Which is it?

    The inrush current that was calculated might have been with the system fed from 440, which would almost be about right,
    it was around 2X the running current I think.

    Photovoltaics provide dc, what kind of inverters are being used? Wouldn't it be a darn sight easier to set the inverters up to
    simply supply three phase power from the git-go, and eliminate the need for an idler and all the associated fooferwaw
    that goes with it?
    The PV system will provide be wired up to provide 110v since that has a wider range of uses.

    600v and 300amp is for testing purposes.

    The goal is to take the 110v step it up; currently I have a 220v 100KVA transformer but I could change it out for 440v 100kva as this would reduce the required running amps from 236 to 118.

    This would still have the issue of managing inrush current, although at 440v the amp would be about 118.

    I've seen and read anywhere that the inrush current can be anywhere from double to six times full load amps.

  18. #36
    Join Date
    Nov 2019
    Country
    UNITED STATES
    State/Province
    Florida
    Posts
    26
    Post Thanks / Like
    Likes (Given)
    2
    Likes (Received)
    0

    Default

    Quote Originally Posted by Bill Simmons View Post
    For the input power, you must multiply the three phase current by approximately 5/3
    to account for the same power from a single phase circuit. I don't think you did that.
    The PV system is 93kW then I took 85% or the 25 year power warranty to get about 79kW of usable power under standard conditions. Those numbers can be adjusted though.

    I'd like to stay focused on powering up the motor etc.

  19. #37
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,793
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8635

    Default

    Quote Originally Posted by newbea View Post
    The PV system will provide be wired up to provide 110v since that has a wider range of uses.

    600v and 300amp is for testing purposes.

    The goal is to take the 110v step it up; currently I have a 220v 100KVA transformer but I could change it out for 440v 100kva as this would reduce the required running amps from 236 to 118.

    This would still have the issue of managing inrush current, although at 440v the amp would be about 118.

    I've seen and read anywhere that the inrush current can be anywhere from double to six times full load amps.
    Transformers have "inrush" too. While of high nominal transfer efficiency, they also DO waste measurable and sometimes significant power even idle.

    PM has recent figures for the effect on a poster or two as to utility bills - transformer left ON 24 X 7 or switched OFF for all but one active shift's actual use.

    You may not have a "bill" here, but you still do have a budget of sorts in the power itself that is available and for what part of any given day.

    The higher the step-up ratio, the harder the hammer on that 120 VAC feed as well.

    Do the simplest of the maths. You are on the short end of a lever.

    Load Amps @ 220 or 440 translate to 4 or 2 times the Amps drawn at the low-voltage feed .... before you even think about single to 3-Phase as well.

    That will be hammering the PV system's inverters, and with "BFBI" at that?

    You can see where a soft-start/slow-rampable VFD with intelligent controls "talking" to the PV system as well as "Headquarters" can be gentler by far?

    Need to survive atmospheric air-mass electrical storms? Near-miss - and closer lightning strikes?

    Not new. Global telcos were at it even before Microwave and satellite arrived.

    There are ways.

  20. #38
    Join Date
    Jun 2001
    Location
    St Louis
    Posts
    18,040
    Post Thanks / Like
    Likes (Given)
    1892
    Likes (Received)
    3044

    Default

    Quote Originally Posted by newbea View Post
    The PV system will provide be wired up to provide 110v since that has a wider range of uses.

    600v and 300amp is for testing purposes.

    The goal is to take the 110v step it up; currently I have a 220v 100KVA transformer but I could change it out for 440v 100kva as this would reduce the required running amps from 236 to 118.

    This would still have the issue of managing inrush current, although at 440v the amp would be about 118.

    I've seen and read anywhere that the inrush current can be anywhere from double to six times full load amps.
    Frankly, I think you have that backwards.

    You can run most any PV up to 600VDC per UL, as the panels should be set uop for it. Unfortunately, that is not super practical, because it is not convenient for any US voltages. (f you wanted 380V, it would be fine.)

    It sounds as if you ought to set up to produce the PV output a bit under 400VDC. From that you can produce 240VAC with an inverter directly, using the P V output directly into the DC bus of the inverter. Any solar inverter of the size you want will handle that fine, there are a number of makers of such units, although cheap they are not.

    From that, you can use transformers to get 120V, which is very likely the lowest power draw you will have.

    Starting from 120V, you would have the highest currents, and consequently the largest losses. Not a good plan, IMO

    Do you plan a battery system for "ride-through" and overnight?

  21. #39
    Join Date
    Jun 2006
    Country
    UNITED STATES
    Posts
    717
    Post Thanks / Like
    Likes (Given)
    610
    Likes (Received)
    75

    Default Sizing start & run capacitors for 100hp 3 Phase motor

    Quote Originally Posted by newbea View Post
    Looking below a lot of people recommend the pony motor but I am currently testing at a factory that builds and tests motors. They have very high voltage and amp rated electricity; well above 600v and 300amp.

    I could use a pony motor since there are a few lying around.
    A pony is a good solution to solving the inrush startup current.
    I have questions about your 50HP load motor though.
    What are you driving?
    Are you actually going to use full rated power and current?
    Is it a hard start load? Ie, does it need to spin up fast/immediately, or can you slow/soft start it?
    Can you use a VFD to drive your 50HP load motor instead of using a RPC?

  22. #40
    Join Date
    Sep 2011
    Country
    UNITED STATES
    State/Province
    Virginia
    Posts
    27,793
    Post Thanks / Like
    Likes (Given)
    7561
    Likes (Received)
    8635

    Default

    Quote Originally Posted by rpseguin View Post
    A pony is a good solution to solving the inrush startup current.
    I have questions about your 50HP load motor though.
    What are you driving?
    Are you actually going to use full rated power and current?
    Is it a hard start load? Ie, does it need to spin up fast/immediately, or can you slow/soft start it?
    Can you use a VFD to drive your 50HP load motor instead of using a RPC?
    He has mentioned a hydraulic system as load, and that that side of it starts UNloaded w/r the 50 HP motor.

    Remote, unattended, intermittent use, and goodly-scale solar powered?
    Could be a positioner? Mayhap for hydro, flood, navigation, or irrigation flow control. Pump-jacks for petro extraction?

    Lots of things as are "remote", the Aaland islands as complicated a land as they be.

    VFD's wants uber-good weather and atmospheric electricity armouring. But so does the PV array and its inverters, so... JFDI.

    Remote control from adjacent brains or a satellite in orbit is an option of a coms link plug-in, if not already on-PCB.


  23. Likes newbea liked this post

Tags for this Thread

Bookmarks

Posting Permissions

  • You may not post new threads
  • You may not post replies
  • You may not post attachments
  • You may not edit your posts
  •