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Baldor 3-phase motor for RPC

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  • Baldor 3-phase motor for RPC

    I'm wiring up a Baldor 40HP motor for an RPC. I crimped/soldered/heat shrink sealed the wires per American Rotary's specifications. What isn't mentioned is the little brown wires that are way smaller the the wires mentioned.
    I was thinking these were wires that are supposed to be grounded to the panel chassis. I tried to get the RPC running yesterday and it just hummed very loud like it was under excessive load. I shut it off and hand spun the armature before hitting the start button and it started to spin, but still didn't sound right.
    Before I start adding capacitors or reversing input leads, I need to know what those little brown wires are really for.

  • #2
    Most likely your best bet is to get the model and serial number off the tag and go to Baldor with it. They make nice motors.

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    • #3
      40hp??? Jeez! Watcha running?
      Location: Jersey City NJ USA

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      • #4
        Fear,

        Is the motor a American Rotary's converter? There should be information on line about the complete system if it is. Sounds like they might be a thermal sensor in the winding's.
        Nickel-city-fab is right Google the motor name plate information and you might find a wiring diagram of the motor.

        When you say before starting to add capacitors, if you are building your own from information on line, you need capacitors to make the motor rotate, as it needs them to produce some phase shift to let the third winding do it's part to get the motor rolling. These need to be START capacitors (often in black round cases) to get this shift and they do NOT stay in the circuit. The other run capacitors (the type in oval silver cases) are to balance the voltage, but this is a point of debate as to if and how much balance is needed if at all.
        Reversing the leads is going to make the motor rotate in the other direction and relocate the power phase or produced phase which might cause you some difficulty if it's an American Rotary converter. 40HP is a big rotary phase converter so it's going to take a few capacitors to get things going either way.

        More information will be needed to help with your dilemma. I'm not the sharpest tool in the shed when it comes to these but others will speak up I'm sure so hang in there and be SAFE your working with some high current with a 40HP motor.

        let us know how it comes out. !

        TX
        Mr fixit for the family
        Chris

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        • #5
          You have bought one of these: https://www.americanrotary.com/products/view/panel
          and are pairing it with your own motor as the idler.
          Is your idler motor wired for 240 or 480VAC?

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          • #6
            Almost absolutely certain the small wires are to a temperature sensor. Might be a switch, might be a thermistor. Ohmmeter will tell you.
            1601

            Keep eye on ball.
            Hashim Khan

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            • #7
              Originally posted by J Tiers View Post
              Almost absolutely certain the small wires are to a temperature sensor. Might be a switch, might be a thermistor. Ohmmeter will tell you.
              Correct.
              See: https://www.baldor.com/api/products/...rawings/CD0180

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              • #8
                From looking online, I'm pretty sure the little "J"-wires for a thermo sensor and using them is completely optional.

                I got the American Rotary panel from another member of the forum and it's sized for a 40HP motor. I can't say how grateful I am, that was awesome. I had to replace some blown start capacitors. I found some NOS American-made ones (all new ones I could find were from China). I soldered the same rating resistors as were soldered to the old ones. I asked American Rotary for a schematic and they couldn't help me because the panel was very old and from many revisions ago. the best they could do was pass me some pictures of another identical panel from the same time. This panel is, I believe, from before American Rotary started getting together with Baldor to make special runs of motors more suited for RPCs. The motor was brand new. I found it in a warehouse in Alabama with a missing fan cover and wiring box and a broken cooling fin but with all the paperwork straight from Baldor. These things typically cost thousands, I got it for a couple hundred and a little footwork to find another fan cover. It spins freely by hand.

                This is a learning exercise. I'm a very competent electrical technician on automotive applications but this has been a fast crash-course on understanding 3-phase and RPCs with communication with American Rotary, members of this forum and plenty of reading material being my only teachers. I quickly found out all the self-professed "commercial electricians" I know don't know squat about 3-phase or much else that I can find useful.

                American Rotary has a symptom/solution checklist and one of the suggested solutions was to add capacitors if it needs it. There's also reversing the input single-phase wires, checking voltages, etc. I know I'm close to this working right, it wouldn't be realistic for a rookie's first RPC build to be plug-n-play without a few bumps in the road.

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                • #9
                  A few pictures for perspective.
                  You may only view thumbnails in this gallery. This gallery has 5 photos.

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                  • #10
                    Originally posted by reggie_obe View Post
                    You have bought one of these: https://www.americanrotary.com/products/view/panel
                    and are pairing it with your own motor as the idler.
                    Is your idler motor wired for 240 or 480VAC?
                    I triple checked to make sure I paired the wires correctly for 240v. The panel is way older than the current ones they sell.

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                    • #11
                      Originally posted by gellfex View Post
                      40hp??? Jeez! Watcha running?
                      16x60 Sharp lathe, a Bridgeport vertical mill and a Millermatic 300, so far. The Miller is rated to take every bit of what the RPC will do. I'm still planning on adding a bandsaw and/or cold saw or ironworker. I want to be able to take on other 3-phase equipment like a surface grinder or what-not as I get to where I need to expand. It's a one-man shop so I might run the lathe and mill at the same time or something like that, which should be within reason but it's not like I'll be running everything at once.

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                      • #12
                        Originally posted by Fear View Post

                        16x60 Sharp lathe, a Bridgeport vertical mill and a Millermatic 300, so far. The Miller is rated to take every bit of what the RPC will do. I'm still planning on adding a bandsaw and/or cold saw or ironworker. I want to be able to take on other 3-phase equipment like a surface grinder or what-not as I get to where I need to expand. It's a one-man shop so I might run the lathe and mill at the same time or something like that, which should be within reason but it's not like I'll be running everything at once.
                        I'm a one man shop too, but since my biggest tool was 2hp I used a 2hp idler for the RPC. I'd be nervous about running a welder on an RPC because they're never balanced perfectly and there's so much wierdness about what happens when you have 2 motors running, but that's probably just my ignorance.
                        Location: Jersey City NJ USA

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                        • #13
                          How many Hp of idler is the RPC control sized for. Looking at the picture, I see only one start capacitor, it's the black plastic one in the front row. What is it's rating in mf.? I doubt that is sized correctly for starting a 40Hp. idler. Might try 20mf per Hp of Idler.

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                          • #14
                            Fear
                            On the motor, wire numbers 4,5,6 should be tied together for 240 Volt operation , then 1 and 7 to one leg, 2 and 8 to the next leg , 3and 9 for the manufactured leg to complete the connection

                            When you first started it and it did not turn, you had no caps in the connections if I read you correctly, and that confirms no movement - thats normal for no caps
                            By spinning the armature , you should be able to get it running , but the spin has to be fast enough
                            Some RPC's use a fractional HP motor, to start the armature spinning, then drop out or use a over-running clutch .
                            Your comments sound like you are not getting support from A R, and frankly, I don't understand that ...This is not black magic !
                            I see no relays, only breakers in the photos, so assume to turn on , you will hit a breaker for start and stop.
                            The number of start caps I see in the photo tell me you need a relay OR a super heavy duty temp on off switch as the start caps cannot stay in the circut.
                            Rich

                            I have built over 60 phase convertors and about 2/3rds were RPC's
                            Every motor and start system is different, but normally you look for 100 Mf per HP for start and 15 Mf per HP when running
                            So your system looks at about 4,000 Mf for start and 500 Mf running..the lights will dim very much A 60 amp breaker will not handle it
                            Last edited by Rich Carlstedt; 04-28-2020, 09:49 PM.
                            Green Bay, WI

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                            • #15
                              Originally posted by reggie_obe View Post
                              How many Hp of idler is the RPC control sized for. Looking at the picture, I see only one start capacitor, it's the black plastic one in the front row. What is it's rating in mf.? I doubt that is sized correctly for starting a 40Hp. idler. Might try 20mf per Hp of Idler.
                              That's an old picture I pulled the damaged capacitors out and left one in for the picture. Here's some pictures I took a few days ago.
                              You may only view thumbnails in this gallery. This gallery has 2 photos.

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