How to hook up power to a Delta 14" radial saw magnetic starter box
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  1. #1
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    Default How to hook up power to a Delta 14" radial saw magnetic starter box

    Guys,

    A few days ago, I lucked into a deal in a 14" Delta radial arm saw model 33-400. According to the data plate and to information I found online the saw has a 3 hp single phase 220v motor.

    When I bought the saw the cutting head and arm were dismounted from the base. Hence, the wire leading from the motor to the magnetic starter box was disconnected from the starter box. The ends of that wire are tinned but otherwise bare with no connectors.

    I have no experience with magnetic starters not even single phase starters. I am unable to determine where the black and white wires coming from the motor, are supposed to be connected inside the box. The colors are green, black, and white. Inside the box all the green wires are connected to the frame. So I'm confident that green is ground (duh!)

    I will genuinely appreciate anybody who can swat me with a clue-by-four.

    Here are two pictures: 1) inside of the starter box; and 2) the wiring schematic from inside the cover to the starter box. I am a complete nincompoop at reading schematics.

    The saw itself has START - STOP buttons mounted in a box on the front. So there are two separate cables now routed to the inside of the starter box: The smaller cable from the start-stop box and the larger 220v single phase, 20 amp power supply cord. Although not clearly shown in the picture of the box there are three holes into it. The power supply cord enters from the bottom right. The START - STOP cable enters from the back just above it. A little to the left of this hole there is a slightly larger hole. I assume (but don't know) that's where the cable from the motor is supposed to enter the box. That hole is visible but a black cable curls around in front of it, almost making it look like it enters the box from there. But it doesn't.

    As best I can tell GREEN is ground and WHITE and BLACK are the two 120V hots. For the moment the only thing I'm uncertain of is: "WHERE DO I CONNECT THE TWO HOTS (BLACK AND WHITE) FROM THE SAW MOTOR INTO THE BOX?"

    Thanks and regards to all.

    Vernon
    Attached Thumbnails Attached Thumbnails delta_saw_box.jpg   delta_saw_schematic.jpg  

  2. #2
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    Keep in mind that with 120V AC you only have one HOT which is or should be the BLACK wire. The WHITE wire is your NEUTRAL which should be at the same potential to the Green wire which is your GROUND.

    The wires coming from the motor use the same convention so Black eventually goes to Black and White eventually goes to White. If you can trace the white through the contactor and heater and do the same with the black you should be all set.

    FYI the gismo top left is the contactor and the gismo to the right of it is a transformer that takes the 120V from the outlet and steps it down to 24V to power the electromagnet in the contactor. That 24V is what goes through the on and off buttons and the buttons power up the main contacts. It's looking like the red wires are all the 24V.

    What's confusing is that the White wire goes to a Black wire on the buss bar. I'd follow that Black and connect the motor White to whatever screw terminal is open at the other end of it. It may well be the silver plated screw on the lower portion of the back of the switch on the left hand side of the box. The motor black would then go on the one empty terminal on the middle buss bar.

    What's important is that the Hot terminal of your outlet makes it's way to the black wire on the motor. Use a meter or continuity tester to assure yourself that this is the case. While you're at it you might test the outlet with a little plug-in polarity tester. A GFCI outlet would be a good idea if you plan to use this saw on a concrete or dirt floor or outdoors.

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    Hi David,

    Your explanation did indeed move the football of my dim understanding toward the goal post. In particular, your post helped me understand much better how the START - STOP button circuit works. However, to be clear, the saw is powered by 240V and not 120.

    Also, I would add that I'm reasonably competent as regards single phase 120 and 240 to the point that I feel totally confident wiring up panels, sub-panels, switches and such.

    However my knowledge and experience stop suddenly and well short of electric motors and motor controllers.

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    Many Delta products up to 2 HP had manual starters, really a special motor-rated snap switch now second sourced (and available in Delta Gray) by Square D.

    This machine is rated up to 5 HP, therefore it has to have a motor starter with a protection means, hence the magnetic motor starter.

    In addition, this machine also has "low voltage controls", usually 24 volts, common in schools and where OSHA rules rule, with the 24 volts produced by the control transformer.

    In such a machine, a three-wire cordset would ordinarily be employed, with one green wire (the so-called goundING conductor) and two black wires (the above-ground conductors). An acceptable and more common alternate is green, black and red wires.

    The blacks (or black and red) would be connected to the terminals labeled L1 and L2.

    Alas, your photo completely obscures the "three-wire control station", which is where the START and STOP buttons are wired.

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    Vernon,

    Do you have it figured out yet? The motor leads connect just as they appear in the schematic...ignore the black white color disparity, someone used the cord they had at hand. The funny switch with the push in handle on the lower left gets one of the wires from the motor...the screw on the bottom terminal is missing, this is T-1 noted in the schematic.

    The other motor lead is attached to the far left terminal of the buss bar...the position that has a wire coming from the mag on top screw but no wire on the corresponding bottom screw. You can see this too in the schematic..last tap on the left of the buss...right next to the incoming BLK & WHT wires.

    Clear as mud..huh!

    Stuart

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    Stuart,

    I think I'm gonna petition the governator to make you an honorary Texan.

    I haven't yet compared your comments to the pictures but I think we might have lift-off.

    Peter: Your comments are somewhat over my head. But I think I'm beginning to understand.

    Thanks to all.

    Vernon

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    Sorry Vernon,
    I did indeed miss all the evidence to the contrary and decide that your saw was wired for 120V. I apologize for that. So yes indeed you have two hots, both black and either can go to either of the two motor leads which happen to be white and black. There are only two open terminals just as I and Stewart have already pointed out. One is the left hand, bottommost terminal on the buss bar. The other is the screw terminal at the back of the reset (I 'm figuring that is what it must be) button on the left hand side of your box. (Just to the left of your Ground buss in the photo you posted). You'll need an 8-32 panhead screw to replace the missing one.

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    The list of "Replacement Parts" is a handy reference to what all is in your box.
    If you can identify each and every device after sifting through all the posts you'll be well on your way to tackling any future machine wiring situation.
    We all use different terminology for the same parts and that definitely adds to the confusion.
    What Delta and I call a "Contactor" is what what Peter calls a "Magnetic Motor Starter" and what Stuart calls a "Mag".

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    "What Delta and I call a 'Contactor' is what what Peter calls a 'Magnetic Motor Starter' and what Stuart calls a 'Mag'"

    Different strokes for different folks.

    The machine has a specialized contactor, that much is true, but it also has an installed auxiliary switch for the "seal" function of the "three-wire control station" and an overload unit.

    Apparently, Delta decided to source these devices as separate units and then assemble their own, rather than buying an off-the-shelf NEMA Size 0 or 1 magnetic motor starter.

    This is the RIGHT way to implement a control on a machine which is used in production.

    My 3 HP Detla Unisaw has just such a control box.

    My other Delta woodworking machine, being rated 2 HP or less, can legally utilize a manual starter (a horsepower-rated snap switch), usually implemented as a START and STOP button which actuates the snap switch.

    The larger machines have the same external switch assembly, but these actually actuate momentary switches which are then wired into the "three-wire control station".
    Last edited by peterh5322; 03-04-2013 at 01:00 AM.

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    Guys,

    I am attaching a close-up of the schematic. My last dangling concern is that the box is improperly jumpered for 200 volts. I ASSUME it is (or should be!) jumpered for 230V because the power plug looks just like a 20 amp air conditioner plug. However, if I'm properly following the schematic it would seem that the black wire with the red plastic connector (see the picture of the open box in the original post) should be on the SECOND plug from the left of the four blade connectors and not the first, as configured here.

    Specifically, I refer to the instructions that say "CONNECT AS PER LINE VOLTAGE" According to my understanding the left-most blade is 200V; the one just to the right of it (now unoccupied) would be the one for 230V.

    Am I wrong about that? Or am I misunderstanding the instructions?

    Otherwise, I think I'm ready to roll.

    Thanks again!

    Vernon
    Attached Thumbnails Attached Thumbnails schematic_close-up.jpg  

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    Vernon,

    I'll go out on a limb here....I think someone has replaced the control transformer and the new item does not conform to the wiring schematic of the old. The actual photo shows the saw is currently jumpered for 230 volt operation which is how you intend to run it, it's good to go this way. I think the schematic pertains to a transformer that was installed from the factory and went up in smoke and was replaced.

    The transformer that is on the saw now shows the proper connection for that transformer and that's how it's wired.

    Stuart

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    From an examination of the complete schematic and the photo of the control box, the control transformer does, indeed, appear to have been replaced.

    It is presently wired for 230 volts in and 24 volts out, confirming my speculation that this was a fully-featured low-voltage motor controller.

    The three small diameter red wires appear to be for the purpose of establishing the "three-wire control station".


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