1947 Model 9A - Page 5
Close
Login to Your Account
Page 5 of 21 FirstFirst ... 3456715 ... LastLast
Results 81 to 100 of 417

Thread: 1947 Model 9A

  1. #81
    Join Date
    Sep 2005
    Location
    Indiana, USA
    Posts
    2,868
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    72

    Post

    Forgive me for being rather ignorant of these matters...
    Me too, John. I've seen an awful lot of variation in the way these motors and switches are wired up, and it can be highly confusing. From what I've been able to figure out, my motor is a split-phase, capacitor-start motor with integral reversing relay:



    There are four stator wires, which I assume are for the main winding, forward start winding, reverse start winding, and common. There is the usual 2-pole centrifugal switch for throwing out the starting winding and capacitor. And there is a replaceable 2-pole reversing relay, which I would guess is supposed to save wear and tear on the drum switch contacts, but I don't know that for sure.

    Here is the wiring diagram I came up with, based on how the lathe was wired when I bought it, the only difference being that I'm bringing the line cord into the motor junction box, rather than the drum switch:



    Note that I'm not showing the ground wire in the diagram. The ground wire from the line cord would be connected to the motor frame, and from there to the switch housing/lathe frame. Hence, the multi-conductor wire needs to have five main conductors plus the ground wire.

    Paula

  2. #82
    Join Date
    May 2004
    Country
    UNITED STATES
    State/Province
    New York
    Posts
    682
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    11

    Post

    My Heavy 10 is also wired using Liquid-tite & THHN conductors. Operating on 110V, I've got 5 conductors going to the Furnas drum switch, the hot leg & just the leads that need to be switched. The neutral goes straight to the motor. Any splices and jumpers were done in a 4" deep box mounted on the rear of the cabinet, which also houses the convenience outlet for the work light. This is the way I wired my 3 previous lathes, all using the same model drum switch.
    Bob

  3. #83
    Join Date
    Apr 2005
    Location
    MA, USA
    Posts
    2,053
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    12

    Post

    Behind its panel, my Hoover motor has four for the run windings, and then two for the start winding. The capacitor, centrifugal switch, and overload protector are all wired internally and aren't seen unless you take the bells off.

    I'd have to take some time to think your drawing though, but the switch wiring seems more elegant than mine. I used a 3-pole, 9-terminal Cutler-Hamer switch. Line went to the center block, load to the outer sets. The upper pole connects the stator in either postion. The lower two poles cross and swap the two start winding wires depending on which direction it's going. This was how the switch was made. It just took me a while to figure out all the paths without any reference (lathe came wired as single direction).

    You mentioned a relay in your motor? Is this one of the fabled GE instant-reversing single-phase jobs? They only made them for South Bend. I have one that came on my Benchmaster mill.

  4. #84
    Join Date
    Feb 2005
    Location
    Columbus, OH
    Posts
    277
    Post Thanks / Like
    Likes (Given)
    1
    Likes (Received)
    9

    Post

    Paula-
    I think I have the same motor setup you do. 5 lead GE motor w/ a Furnas Drum switch.

    Lucky for me - you are about a month ahead of me on rewiring. I will watch your postings and learn.
    Something is not right on my setup - I currently get a bit of a shock when I move the drum switch into FWD.

    Are you planning on replacing any of the wiring inside the bells? If so, with what?

    On my motor the insulation doesn't look that great - a couple of cracks. I was going to get out the heat shrink tubing but then thought I might as well replace the wire while I'm in there cleaning out 60 years of chips and grit.

  5. #85
    Join Date
    Dec 2002
    Location
    Monterey Bay, California
    Posts
    10,260
    Post Thanks / Like
    Likes (Given)
    28
    Likes (Received)
    220

    Post

    "I was going to get out the heat shrink tubing but then thought I might as well replace the wire while I'm in there cleaning out 60 years of chips and grit"

    Clean, mechanically, with a soft toothbrush, then apply heat shrink tubing, leaving the far end (that which is closest to the windings, etcetera) a little loose.

  6. #86
    Join Date
    Sep 2005
    Location
    Indiana, USA
    Posts
    2,868
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    72

    Post

    Last night, mostly for curiosity sake, I went through and traced all the motor wires, checking with an ohmmeter, numbering and documenting as I went. It turns out that my original description was a bit off.

    Apparently there are just two windings -- start & run. The start winding is in series with a capacitor, and by reversing the direction of current through this series, a reversing impulse is generated.

    Here's the diagram that resulted, in schematic form, showing the complete wiring arrangement for my motor/switch setup. The T1 thru T5 wires are the ones emerging from the motor housing (and were labled as such with small metal tags at the factory), and correspond to the external wiring diagram in my previous post.



    Some notes about this diagram:

    1) The "H" and "N" refer to the hot and neutral legs of the 110 volt line. I numbered wires 6 thru 9 just for my own documentation and use at reassembly.

    2) The drum switch is the same one shown in my previous post, just rearranged in schematic form. Note that the upper 2-throw contact simply connects the hot line to T3 whenever the switch is moved to the FWD or REV positions, while the two bottom 2-throw contacts simply reverse the direction of current flow through the start winding/capacitor circuit. The contacts are show in the FORWARD position.

    3) The centrifugal switch contacts are shown as they would be with the motor at rest, the T1 contact being connected to line 8. When the motor shaft reaches a set speed, the centrifugal throwout mechanism retracts away from the switch contacts, allowing T1 to contact line 9.

    4) As some of you with ladder-logic experience may recognize, the relay is internally wired to be "self-sealing", that is, though the relay coil is originally energized thru the starting coil circuit, once the contact is pulled in it is maintained by the current flowing thru the run winding, even after the starting circuit is disabled by the centrifugal switch.

    5) The diagram is shown at precisely the instant that the drum switch is moved to the forward position. The relay has not yet pulled in the contact on line 7 to energize the run winding, and therefore the cetrifugal mechanism has not yet de-energized the starting circuit.

    I don't know enough about these motors to understand just how this circuit does what it does. I just know that it's wired as shown above. When I was running this lathe prior to disassembly, I never really tested to see how quickly it would reverse. It seems to be a fairly traumatic exercise, even for motors that are designed to be "instant reversing", and I didn't want to push it. I would usually let it coast down a bit before reversing.

    I once installed an instant-reversing, single-phase motor on a drill press I used to own. It came from Grainger, and I would guess that it was set up much like this motor, with the exception of using a solid-state relay. Could be wrong about that too.

    You mentioned a relay in your motor? Is this one of the fabled GE instant-reversing single-phase jobs?
    Not sure about that, John. Here is the information from the motor plate, for what it's worth:

    General Electric A-C Motor
    Relay Reversible
    Model 5KC47AB2169A
    HP 1/4
    Phase 1
    Type KC
    RPM 1725
    Volts 115
    Amps 3.8
    Cycles 60
    GEJ: 1404
    Temp Rise: 40 deg. C
    Time Rating: Cont. PBK

    On the drum switch:

    Reversing Controller
    Style RSB4
    Made for South Bend Lathe Works
    By Furnas Elect. Co.

    Here are some pics of the relay, which was mounted behind a plate on the end of the motor:





    Are you planning on replacing any of the wiring inside the bells?
    It's still in pretty good shape, so it shouldn't be necessary. The grommets that line the (3) holes where the wires emerge from the motor housing are another story. They have almost completely disintegrated. I've purchased some new neoprene grommets that fit very well, though they don't have the individual holes for each wire, like the originals. Though I only need three, I had to buy a minimum quantity, so I've got PLENTY left over if anybody else needs some.

    Peter's heat-shrink tubing method sounds good to me.

    Lepton, let us know of your progress as you work on your motor.

    Paula
    Last edited by Paula; 06-30-2009 at 05:41 PM. Reason: spelling

  7. #87
    Join Date
    Apr 2005
    Location
    MA, USA
    Posts
    2,053
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    12

    Post

    I think that's one of those motors. Mine's a little different, but also from an SB.

    The purpose of the start setup is pretty simple, at least on mine. The problem with most single phase motors is that the start circuit is disabled by the centrifugal switch. So if you want to reverse one you need to wait for the motor to slow down or stop. The relay basically gets around that by energizing the start circuit every time the power is cut and then restored.

  8. #88
    Join Date
    Dec 2002
    Location
    Monterey Bay, California
    Posts
    10,260
    Post Thanks / Like
    Likes (Given)
    28
    Likes (Received)
    220

    Post

    Instant-reversing with single-phase is accomplished by:

    1) a relay which is initially unselected, but which "remembers" that is was selected until such time as power is removed, at which time it becomes unselected, again, and

    2) a double-throw, not a single-throw centrifugal switch, which is electrically interlocked with the relay, and through which interlock it is able to accept commands from the external drum switch so as to:

    3) cause the start winding to become a braking winding, when the drum switch is reversed, and

    4) once braking has been completed, this same start winding, having most recently been utilized as a braking winding, again becomes a start winding, thereby reversing the motor.

    The drum switch shown in Paula's diagram is most like a three-phase drum switch with which I am familiar.

    There is a similar drum switch which is intended for use on single-phase, and which allows for all power, including the neutral, to be disconnected from the line.

    As shown in Paula's diagram, should the cordset be miswired to have the ungrounded conductor on the larger pin, or should the receptacle be similarly miswired, then the wiring within the machine is live with respect to ground, even if the drum switch is in the neutral (OFF) position.

    This flaw cannot happen with a single-phase drum switch, as provision is made to switch both the line and the neutral conductors.

  9. #89
    Join Date
    Feb 2004
    Location
    peekskill, NY
    Posts
    24,692
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    4727

    Post

    Clever design. Think of the relay and
    centrifugal switch as being the two switches
    in a two-way lamp circuit. The two horizontal
    wires between them are the 'travellers' as an
    electrician would call them.

    The start winding and capacitor are wired up
    in the regular fashion, with the two bottom
    poles of the three pole contactor X-wired to
    make it reversing. So the start winding
    will be put in phase, or out of phase, with
    respect to the run winding depending on which
    way the switch is operated.

    The top pole is wired right across between
    the two contacts and simply serves to energize
    the motor via the incoming hot leg, no matter
    which way the switch is operated.

    So the first thing that happens is, when the
    run switch is closed is the contactor sucks
    in from the current in the run winding flowing
    through it. The centrifugal switch is already
    closed as the motor is at rest. Thus the
    start winding is energized and the motor spins
    up to speed in some direction.

    Now consider what happens when the drum switch is
    instant reversed. I has to go through "off"
    to do this and when this happens the contactor
    relay will drop out. In doing so the start
    winding is now connected into the circuit again.

    Then the drum switch handle is brought through
    the "off" postion and put into reverse. This
    is where I get a bit hazy but I'm going to
    make a stab at this:

    One would think that the contactor relay would
    immediately suck back in again, disconnect the
    start windings (remember, the motor is still at
    speed, the cent. switch is open now) and the
    motor will continue to run in the same direction.

    My personal guess is that the back EMF across
    the motor windings will keep the contactor from
    sucking in until the rotor speed drops down
    pretty far - probably far enough for the cent.
    switch to close again. As long as the relay
    remains de-energized, the start winding will
    be connected and will tend to force the rotor
    to slow its forward rotation and eventually,
    once it goes to zero, the cent. switch will
    close, the motor back EMF will be zero, and the
    contactor will close at this time.

    That sets the stage for the motor to spin up
    to speed in the reverse direction, until the
    cent. switch opens once again.

    Key to this theory is the idea that the contactor
    relay is sensing the motor's back EMF. If the
    story above is really true, then doing an
    "instant reverse" at the drum switch should cause
    the following sequence of events to happen:

    1) drum switch put to "off"

    2) contactor drops out

    3) drum switch brought over to "reverse"

    4) contactor does *not* suck in at this point

    5) motor slows

    6) centrifugal switch closes

    7) motor comes to a halt

    8) contactor finally sucks in

    9) motor runs up to speed

    10) cent switch opens again

    Just a theory for folks to shoot holes in.

    Jim

  10. #90
    Join Date
    Dec 2002
    Location
    Monterey Bay, California
    Posts
    10,260
    Post Thanks / Like
    Likes (Given)
    28
    Likes (Received)
    220

    Post

    "Think of the relay and centrifugal switch as being the two switches in a two-way lamp circuit. The two horizontal wires between them are the 'travellers' as an electrician would call them."

    A useful analogy, Jim.

    The key here is the motor's relay and centrifugal switch always have an initial position which is known, just as does the external drum switch's contacts.

    Then, irrespective of the direction of rotation of the motor, executing a reversal command from the drum switch will cause whatever sequence is necessary to happen to cause an instant reversal to occur, as the "travelers", as you called them, remember what goes where, and when.

  11. #91
    Join Date
    Oct 2001
    Location
    Lewes, DE.
    Posts
    1,419
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Post

    Hi There,

    The GE instant reversing motors I have seen (only 2) had four leads. They weren't numbered but the leads were colored (2 black, 2 yellow). I found a diagram for it in my motor rewinding text book ( Electric Motor Repair by Rosenberg & Hand). What I find interesting is the lead numbering. From what I see, it isn't NEMA standard (probably built before the standard?). What I find very interesting is that your motor has the starting capacitor in line even when reversing? (That is a bit hard on the capacitor). I have included a diagram of the four lead version with NEMA numbers for the leads.



    Good Luck!
    -Blue Chips-
    Webb

    [ 12-18-2006, 11:53 AM: Message edited by: Paula ]

  12. #92
    Join Date
    Dec 2002
    Location
    Monterey Bay, California
    Posts
    10,260
    Post Thanks / Like
    Likes (Given)
    28
    Likes (Received)
    220

    Post

    "... 'Electric Motor Repair' by Rosenberg & Hand ..."

    The best of these (and, most affordable, too) is the earlier Rosenberg edition.

    The Rosenberg edition has lots of info on now obsolete motor configurations, such as those seen in the machinery that are routinely discussed in these forums.

    Instant-reverse motors are discussed in detail in the older edition, possibly because these, then, had wider applications, beyond the obvious "commodity" garage door and entrance gate opener applications.

    Sometimes, older is better.

  13. #93
    Join Date
    Oct 2001
    Location
    Lewes, DE.
    Posts
    1,419
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Post

    Hi There,

    Sometimes, older is better.
    Quite true! If we didn't like older things, we wouldn't be addicted to South Bend Lathes.

    I've been doing a bit more study of Paula's diagram and I think the internals of the relay are incorrect. According to the diagram, ALL the current the motor is using passes though the relay coil . That just doesn't seem right.

    -Blue Chips-
    Webb

  14. #94
    Join Date
    Sep 2005
    Location
    Indiana, USA
    Posts
    2,868
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    72

    Post

    ...I think the internals of the relay are incorrect. According to the diagram, ALL the current the motor is using passes though the relay coil . That just doesn't seem right.
    That does seem unusual, but the coil could easily be rated for the same current as the motor windings. Maybe it has something to do with Jim's theory about the back EMF delaying the relay coil's change of state. I will admit that most relays I've seen do not have coils that are rated at anywhere near their contact rating, by design.

    Paula

  15. #95
    Join Date
    Oct 2001
    Location
    Lewes, DE.
    Posts
    1,419
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Post

    Hi There,

    but the coil could easily be rated for the same current as the motor windings.
    Well, that could be possible. But there is something else that bothers me.

    If I understand your drawing, current from the "H" (Hot lead I assume) passes through the drum switch and on one branch, passes to the run windings and on to terminal 7 on the relay.

    At the same time, current from "H" passes through the drum switch throught the start winding and starting cap. and back though the drum switch and on to the centrifical switch at T1. There (if the diagram is representing the state of switches and relays at start-up), current passes thought terminal 8 and the relay coil back to the "N" (Neutral I assume) lead.

    So there is current passing through the start winding and cap. initially and when the relay energizes, the contact 7 is switched from 9 to 8 and current can now pass though the run winding and the motor can start turning. Okay, I see that.

    As the motor speeds-up in RPM and reaches about 75% of its rated RPM, the centrifical switch "switches" T1 from 8 to 9 and the start windings and cap. disconnect. Now the motor is running.

    Now the drum switch is moved from one direction to the other direction (i.e. reversed). The momentary interuption of current should make the relay open the contacts at 8 and close them at 9. At this point, there is no current flow through the motor! Very quickly, the relay re-energizes and the contact at 9 opens and closes at 8 again. The run windings have current flow again but the motor hasn't slowed down enough for the centrifical switch to change its position. So, no current is flowing through the start windings and the motor will not reverse!

    Well, at least, that is how I see it. Am I missing something?

    Good Luck!
    -Blue Chips-
    Webb

  16. #96
    Join Date
    Dec 2002
    Location
    Monterey Bay, California
    Posts
    10,260
    Post Thanks / Like
    Likes (Given)
    28
    Likes (Received)
    220

    Post

    If the reversal is initiated from a stopped state, the drum switch alone is all that is necessary to accomplish reversal.

    If the reversal is initiated from a running state, a current sensitive relay, and a two pole single throw centrifugal switch are necessary to accomplish reversal.

    Assuming a running state, the following actions happen:

    1) the drum switch is actuated, thereby commanding a reversal,

    2) the second set of contacts on the centrifugal switch route starting power to the starting winding, but in reverse, thereby braking the rotor, usually within a second, give or take,

    3) when the rotor is nearly stopped, the centrifugal switch drops out, and is again in the starting state,

    4) the current sensitive relay drops out, thereby allowing starting mode to be initiated,

    5) the centrifugal switch initiates a starting sequence, this time in reverse, as commanded; now, instead of being utilized as a braking winding, the starting winding is being utilized as a starting winding,

    6) the current sensitive relay "picks", indicating a running condition, and, coincidentally, enabling another instant reversing sequence, and, finally,

    7) the centrifugal switch drops out as the motor is again running.

  17. #97
    Join Date
    Feb 2004
    Location
    peekskill, NY
    Posts
    24,692
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    4727

    Post

    Webb, you have correctly identified the
    'head scratcher' for me in that circuit. For
    it to work as drawn, the relay cannot
    re-engergize immediately after the controller
    handle is thrown through 'off' to 'reverse.'

    If it does, the ckt as drawn could not work.

    So my suspicion is, given paula's typical
    attention to detail, is that a) it's drawn
    as built, b) it works, and c) the relay
    must hold off.

    Why would that be?

    Think of the relay as being hung between
    two terminals. One of them is incoming power
    hot, the other is the end of the run winding.

    The relay energizes if and only if it sees
    a potential difference between those points.

    This happens when the motor is stopped, and
    the incoming line is hot.

    But if the motor has been running, it will have
    some back emf present at the run winding
    terminal the relay is hooked to. Think of this
    as connecting an incandescent lamp to two
    hot legs. The lamp stays off. The relay
    stays de-energized, until the back emf has
    decayed away - until the motor has spun down.

    Think of the relay as a sort of current mode
    potential relay, as used in modern self-starting
    phase converters.

    Just a guess.

    Jim

  18. #98
    Join Date
    Oct 2001
    Location
    Lewes, DE.
    Posts
    1,419
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    1

    Post

    Hi There,

    2) the second set of contacts on the centrifugal switch route starting power to the starting winding, but in reverse, thereby braking the rotor, usually within a second, give or take,
    I have studied the drawing provided and I don't see how any current can flow in the start circuit until the centrifical switch has switched T1 from 9 back to 8. There isn't any current path back to the Neutral. This won't happen unitl the RPM drop below the centrifical switches threshold (about 75% of rated RPM).

    But if the motor has been running, it will have
    some back emf present at the run winding
    terminal the relay is hooked to. Think of this
    as connecting an incandescent lamp to two
    hot legs. The lamp stays off. The relay
    stays de-energized, until the back emf has
    decayed away - until the motor has spun down.
    This may be true but it doesn't matter what state the relay is in if the centrifical switch hasn't switched T1 from 9 back to 8. Until then, there isn't a current path!

    Now I have the greatest respect for Paula and the work exibited on this site but anyone can make a mistake (including myself). The other thought I have is that this is a very old lathe and who knows whom has been "tinkering" inside it before Paula's "custodianship." Perhaps leads/connections were mixed-up by a previous custodian? I just suggest that Paula recheck everything again just to make sure.

    Good Luck!
    -Blue Chips-
    Webb

  19. #99
    Join Date
    Dec 2002
    Location
    Monterey Bay, California
    Posts
    10,260
    Post Thanks / Like
    Likes (Given)
    28
    Likes (Received)
    220

    Post

    "Think of the relay as a sort of current mode potential relay, as used in modern self-starting phase converters."

    A starting relay, such as that used in RPCs, may be current-sensitive, or it may be potential-sensitive, usually with equal capabilities.

    One of the earliest General Electric patents for running polyphase motors on single-phase disclosed a current-sensitive relay.

    The present offerings, of which GE is a major player, are potential-sensitive.

    One patent for a well-known line of static converters claims more reliable operation with potential relays when a second potential relay is used to lock-out the first, thereby preventing "chattering" in the first. Sort of an electro-mechanical "dead band" (hysteresis).

    I suspect current sensitivity (not potential sensitivity) is being used in the instant case of an instant-starting motor, for a similar reason.

  20. #100
    Join Date
    Sep 2005
    Location
    Indiana, USA
    Posts
    2,868
    Post Thanks / Like
    Likes (Given)
    0
    Likes (Received)
    72

    Post

    This has turned into quite a discussion!

    Regarding the accuracy of that schematic... yes, anyone can make a mistake, but I'm very conscientious about these sorts of things, and I would say that I'm 99.9% sure that the schematic accurately reflects the actual circuit as found. Heck, I'd bet the motor on it. (I am betting the motor on it!)

    As Webb pointed out, it's possible that someone may have modified the circuit in the past, though there was no evidence to indicate any tampering. Usually, unqualified tinkerers leave fairly obvious indications of their having inflicted themselves on the apparatus.

    Nevertheless, the motor did work prior to disassembly, though I was not brave enough to slam it into reverse from full-speed forward. As has been mentioned, the question is not how the motor will respond when reversing in a stopped (or slow speed) condition, but what happens when the lever is thrown rapidly into reverse before the motor has had time to slow down appreciably.

    I think it may be a mistake to assume that the relay will respond in an instant reverse situation the same way it does in a slow/stop reverse situation. Things get complex when alternating currents, inductance, residual magnetic fields, L/C circuits, etc. are involved. I don't claim to have a clear understanding of all this, but I do believe that the design of the relay is specific to the application here.

    The relay itself doesn't appear to be non-destructively disassemblable, but I can see enough of the coil to verify that the wire used is at least as heavy as that used in the motor windings, and has no measurable resistance (at least with my crude VOM). This leads me to believe that it is intended to be a current-sensitive relay, and may not behave in a motor starting application the way we might otherwise expect.

    In any event, I will be reassembling the motor in accordance with that schematic (I have nothing else to go by), so if I did make a mistake in documenting the configuration (it CAN'T be very far off), then I guess I'll find out soon enough. Meanwhile, if anyone has any specific suggestions about how it should be wired, I encourage them to speak up.

    Paula

    By the way, I really appreciate all of your thoughtful input!


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
  •