VFD/Soft start ?

ArkansasoffgridArkansasoffgrid Solar Expert Posts: 118 ✭✭
If adding a VFD/soft start to a traditional 220 V well pump, does the pump have to be pulled or can the VFD/soft start be wired in at well head?
8-420AH US Battery L-16s, Midnite Classic 150cc, Whiz Bang Jr, Magnum MS4448PAE inverter/charger,  4590w Canadian Solar panels. Honda EU2000i generator.

Comments

  • BB.BB. Super Moderators, Administrators Posts: 31,082 admin
    Re: VFD/Soft start ?

    If the pump motor is the "correct type", VFD just needs to be installed at the well head.

    As I understand, you need a "three wire" pump motor. Either a motor with an external start capacitor (at the well head) or a three phase motor (rare for an existing residential well pump). The standard two wire pump cannot use a VFD.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • ArkansasoffgridArkansasoffgrid Solar Expert Posts: 118 ✭✭
    Re: VFD/Soft start ?

    Three wire reference as in 2-120v carriers and a ground? That's what I have.
    8-420AH US Battery L-16s, Midnite Classic 150cc, Whiz Bang Jr, Magnum MS4448PAE inverter/charger,  4590w Canadian Solar panels. Honda EU2000i generator.
  • BB.BB. Super Moderators, Administrators Posts: 31,082 admin
    Re: VFD/Soft start ?

    No--It is that the motor has (at least) two sets of field coils offset from each other... A single phase motor has one set of coils that do not provide a rotating field to start the motor.

    A three phase motor has three sets of coils (120 degrees apart) and naturally has a rotating field that "drags" the armature around.

    A three wire motor has a main set of windings and a second set that is (usually) connected to a starting capacitor that provides an "offset" voltage/current to the starting coil. This provides the rotating field that can rotate the armature to start the motor. And there is usually some sort of switch that turns off the second coil once the motor is up to speed.

    If the capacitor is at the well head, you have access to both sets of coils. If the capacitor is in the motor, then you do not and connect connect the VFD to both sets of coils.

    More or less--There are a huge number/variation of motors out there.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • peakbaggerpeakbagger Solar Expert Posts: 341 ✭✭✭
    Re: VFD/Soft start ?

    My understanding is that if the capacitor is out of the hole, usually in control box, where the power feed is attached, it can be converted. I believe that there needs to be 3 insulated wires and one ground. Franklin Electric sells a VS drive that plugs into a standard capacitor box. I haven't used one but its on my list.
  • hemmjohemmjo Solar Expert Posts: 90 ✭✭
    Re: VFD/Soft start ?

    You may have trouble with a soft start on a well pump. Sometimes pumps get a bit "stuck", sand or scale etc can get it. If they don't have that high torque jolt, then motor may stall?

    I have a VFD on my lathe to convert single phase house current to 3 phase for the lathe motor. Soft start is awesome, but as speed goes down so does torque. Thus is unlike a regular electric motor what makes the most torque at start-up.

    just my $.02

    John
    Two systems in the Dominican Republic  http://villagemountainmission.org/
    installed Feb 2014 at 19.796189° -70.893594°, Classic 150 + WBJR, KISAE SW1210, MN Battery Monitor, IOTA DLS 55/IQ4,  4- Solar World 275w, 4-6v x 225ah Trace Batteries
    installed Feb 2015 at 19.795733° -70.893372°, same components  as above
    Honda PowerMate PC0497000, 7000/8750w generator - powers the well and chargers maybe once a week






  • jonrjonr Solar Expert Posts: 1,384 ✭✭✭✭
    A VFD and a soft-starter added to a typical residential well pump are completely different things. The former is for 3 phase motors, the latter is for single phase.

    I am available for custom hardware/firmware development

  • BB.BB. Super Moderators, Administrators Posts: 31,082 admin
    I think some VFD's can be added to "three wire" single phase motors (motors with a main and a starting winding). I think that is what Franklin pumps does.

    But, three phase motors are the typical application. Both induction and permanent magnet motor type.

    I don't know much about VFDs, but they do look very interesting. Because VFDs are typically MSW (Modified Square Wave) output--The motors need to be rated for VFD or not operated very near maximum power. MSW causes motors to run with more current, and therefore run hotter. (I think--as I understand).

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jonrjonr Solar Expert Posts: 1,384 ✭✭✭✭
    I found only this quote from Franklin: "While Franklin's single-phase submersible motors are designed only for full voltage/full frequency operation, Franklin's three-phase submersible motors can be operated with VFDs provided certain guidelines are addressed and followed".

    I am available for custom hardware/firmware development

  • BB.BB. Super Moderators, Administrators Posts: 31,082 admin
    Interesting... Looks like I was wrong.

    -Bill
    Near San Francisco California: 3.5kWatt Grid Tied Solar power system+small backup genset
  • jonrjonr Solar Expert Posts: 1,384 ✭✭✭✭
    I don't know - the description of the Franklin Monodrive sure sounds like variable speed for a single phase pump. Maybe the quote was old.

    I am available for custom hardware/firmware development

  • Texas WellmanTexas Wellman Solar Expert Posts: 153 ✭✭
    Franklin makes a VFD that will work with most 3-wire motors up to a certain horsepower. There is also one that works with 2-wire pumps. I think that the 3-wire motor has soft-start capability but the 2-wire does not. The 2-wire can slow down once it is started but cannot soft start. Look up Franklin Monodrive if you're curious. The SubDrive 2W is what you need for a two wire motor.
  • waynefromnscanadawaynefromnscanada Solar Expert Posts: 3,009 ✭✭✭✭
    VFD generally require 3 identical coils in the motor to operate correctly. 3 coils as in 3 phase motors. A 3 wire + ground single phase motor has only 2 coils. One is the normal "run" winding, the other of smaller gauge wire is the "start" winding and is intended to be powered through a start capacitor, and only for only a short time while the motor is brought up to speed. It may also, in some motors, be designed as both a start winding and a capacitor run winding. In capacitor run mode, a much smaller capacitor is used and current flow is greatly reduced compared to the "run" winding, which prevents overheating and burnout.
    2 wire + ground submersible pump motors usually don't have a built in start capacitor, which is why they tend to be much harder to start on inverters than 3 wire + ground motors which have above ground start/control boxes with start capacitor.
    Sorry, I should have stated I was referring to conventional motors such as the Franklin, not to advanced perm magnet types etc.
  • Texas WellmanTexas Wellman Solar Expert Posts: 153 ✭✭
    Some of this information is correct and some is not quite. It depends on the manufacturer. Franklin electric at one time had a monopoly on submersible well motors but since they decided to get into the pump business as well there are now 3-4 serious manufacturers for submersible well pump motors. The Faradyne motor (Joint Venture between Pentair and Goulds) uses a PSC in their 2-wire motors, Franklin uses the BIAC switch. Grundfos also has their own submersible motors but I do not know the design of their 2-wire motors (PSC or ???).

    With 3-wire pumps you can either use CSIR or CSCR. CSIR is start-capacitor only while the CSCR uses a start cap and a run cap. The run cap keeps the start winding in use after starting and slightly reduces the energy usage of the motor. I'm not terribly familiar with all the aspects but I do not believe that the single phase VFD's can go beyond 60 hz, only ramp down, which in my mind negates many of the reasons to install one.

    For the CSIR or CSCR the motor is the same, you just use a different control box.
    VFD generally require 3 identical coils in the motor to operate correctly. 3 coils as in 3 phase motors. A 3 wire + ground single phase motor has only 2 coils. One is the normal "run" winding, the other of smaller gauge wire is the "start" winding and is intended to be powered through a start capacitor, and only for only a short time while the motor is brought up to speed. It may also, in some motors, be designed as both a start winding and a capacitor run winding. In capacitor run mode, a much smaller capacitor is used and current flow is greatly reduced compared to the "run" winding, which prevents overheating and burnout.
    2 wire + ground submersible pump motors usually don't have a built in start capacitor, which is why they tend to be much harder to start on inverters than 3 wire + ground motors which have above ground start/control boxes with start capacitor.



  • Dave AngeliniDave Angelini Solar Expert Posts: 5,508 ✭✭✭✭✭
    I was looking at a Grundfos cutaway at the Fresno Airport in the central valley of CA, there is a factory in Fresno and the standard SQ looks like a three phase motor. All the VFD electronics are in with the motor/pump. The SQ is a 2 wire 120 or 240 vac depending on model. There is a ground connection to the pump but I have seen it installed without it connected.
    With just 2 wires the SQ will [h=2]Features and benefits[/h]
    • Dry-running protection
    • Permanent magnet motor with high efficiency
    • Wear resistance from floating impellers
    • Protection against upthrust
    • High flow velocity
    • Soft-starts reduce wear on motor
    • Over- and under-voltage protection
    • Overload protection
    • Over-temperature protection.
    With the external controller it will,
    [h=2][/h]
    • Variable motor speed controls (with connection to the CU 301)
    • Connection to the CU 301 for two-way communication.
    "we go where power lines don't" Sierra Mountains near Mariposa/Yosemite CA
     http://members.sti.net/offgridsolar/
    E-mail [email protected]

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