Announcement

Collapse
No announcement yet.

Stone Hammer Simple RPC issues

Collapse
X
 
  • Filter
  • Time
  • Show
Clear All
new posts

  • Stone Hammer Simple RPC issues

    Click image for larger version

Name:	IMG_2972.PNG
Views:	289
Size:	3.12 MB
ID:	1884144 JTiers had mentioned this simple setup that I tried with no luck,maybe used motor is no good or not suitable for this setup or I have wiring wrong.I have it wired low voltage as pic shows with 230 volt 1 ph with each hot going to 1 and 2 with 3 empty to generate third leg,had motor turning 1600 rpm with pony motor before turning on 230 volt 1ph,trips 70 amp breaker instantly.It had no load on 3 ph side. Click image for larger version

Name:	IMG_2973.PNG
Views:	320
Size:	125.3 KB
ID:	1884143

  • #2
    pony rotation the wrong way?
    I tried the same thing with a 3ph motor and I couldn't make it go., but I was not 100% confident the motor was good before attempting

    Comment


    • #3
      If I had to guess you need to get it closer to 1725. I've started mine before I got it setup with capacitors and such but I got it real close to 1725 before applying the power.
      olf20 / Bob

      Comment


      • #4
        Since you presumably have no way to see that the motor itself runs on 3 phase, the first thing I would do would be a simple resistance test for the windings to eliminate the possibility of shorts or opens before trying to use it as an RPC.
        "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

        Comment


        • #5
          There is no direction of rotation for single phase, so that should not be an issue.

          That has a code letter typical for 10 HP, 6.7 kVA per HP, or close to 200A inrush possibly, but that is at zero speed (locked rotor). Popping breaker instantly when connecting to power at a much higher rpm seems to indicate a problem.

          The resistance test likely is going to indicate very little, the resistance will be pretty low even on a good motor, most ohmmeters may not show much difference between normal and shorted. May as well try it though, you might find something

          It really needs a low resistance ohmmeter to find a resistance issue in that size motor, and even then you might miss things like a shorted turn.

          Take a good look at the wiring and make sure there is nothing obvious.
          CNC machines only go through the motions.

          Ideas expressed may be mine, or from anyone else in the universe.
          Not responsible for clerical errors. Or those made by lay people either.
          Number formats and units may be chosen at random depending on what day it is.
          I reserve the right to use a number system with any integer base without prior notice.
          Generalizations are understood to be "often" true, but not true in every case.

          Comment


          • #6
            You can rig up a winding tester with a battery and a buzzer (or bell), especially if you can find one rated for 1.5V or 3V as once were used for doorbells (which is where the term "doorbell battery" came about). Using such a device to test continuity will usually indicate a shorted winding by a different sound. A shorted winding will have very little inductance, and so will draw about the same current as a direct short. A good winding will introduce a delay in current and the sound should be lower in frequency. You could also use a Variac to apply some AC voltage to the winding. A good winding will have significant reactance and a higher voltage can be applied before it draws as much current as a shorted turn.
            http://pauleschoen.com/pix/PM08_P76_P54.png
            Paul , P S Technology, Inc. and MrTibbs
            USA Maryland 21030

            Comment


            • #7
              Originally posted by olf20 View Post
              If I had to guess you need to get it closer to 1725. I've started mine before I got it setup with capacitors and such but I got it real close to 1725 before applying the power.
              olf20 / Bob
              No way. That's a short. Dad's RPC is a 7.5 or 10 HP motor (doesn't say, but is rated to start 7.5HP) and even if it fails to start it takes a couple of seconds to trip a 30 amp breaker. If it's popping a 70 amp, there are much bigger issues.
              21" Royersford Excelsior CamelBack Drillpress Restoration
              1943 Sidney 16x54 Lathe Restoration

              Comment


              • #8
                Originally posted by The Metal Butcher View Post

                No way. That's a short. Dad's RPC is a 7.5 or 10 HP motor (doesn't say, but is rated to start 7.5HP) and even if it fails to start it takes a couple of seconds to trip a 30 amp breaker. If it's popping a 70 amp, there are much bigger issues.
                Yes, generally breakers are inverse time types, which means they open faster on a high current, and take more time for a lower overload.

                As I mentioned, opening instantly is a problem, likely a short, not for sure a short. That's why to check the wiring. Mostly in such a case I find a wire touching ground or another wire. Can be a strand that got loose and is sticking somewhere you don't notice.

                Even a shorted turn would take more time, likely.
                CNC machines only go through the motions.

                Ideas expressed may be mine, or from anyone else in the universe.
                Not responsible for clerical errors. Or those made by lay people either.
                Number formats and units may be chosen at random depending on what day it is.
                I reserve the right to use a number system with any integer base without prior notice.
                Generalizations are understood to be "often" true, but not true in every case.

                Comment


                • #9
                  You could also try connecting L1 and L2 to T2-T3 or T3-T1.
                  http://pauleschoen.com/pix/PM08_P76_P54.png
                  Paul , P S Technology, Inc. and MrTibbs
                  USA Maryland 21030

                  Comment


                  • #10
                    Click image for larger version

Name:	IMG_2974.JPG
Views:	254
Size:	1.85 MB
ID:	1884181
                    Originally posted by The Metal Butcher View Post

                    No way. That's a short. Dad's RPC is a 7.5 or 10 HP motor (doesn't say, but is rated to start 7.5HP) and even if it fails to start it takes a couple of seconds to trip a 30 amp breaker. If it's popping a 70 amp, there are much bigger issues.
                    Originally posted by J Tiers View Post

                    Yes, generally breakers are inverse time types, which means they open faster on a high current, and take more time for a lower overload.

                    As I mentioned, opening instantly is a problem, likely a short, not for sure a short. That's why to check the wiring. Mostly in such a case I find a wire touching ground or another wire. Can be a strand that got loose and is sticking somewhere you don't notice.

                    Even a shorted turn would take more time, likely.
                    Sorry Guys I need new glasses,after removing a bunch of single terminal connectors from metal bar did not notice remaining ones were tyed together as pic shows.Motor started with no noise or any other issues checked RPM 1810 about 50 over spec,voltage on 2 lines that were tyed to 1 ph was 121&124 and third leg was 175.I grounded black probe from meter and checked output with red probe,is meter on correct setting as pic shows.

                    I don't understand how motor can put out higher voltage on the 2 legs that connected to 1ph without back feeding into line power.

                    Comment


                    • #11
                      You don't really care about voltage to ground, moreso voltage between phases.

                      1810 isn't that much over spec. 1800 RPM is synchronous speed for 60hz, 1750 is the full load RPM.
                      21" Royersford Excelsior CamelBack Drillpress Restoration
                      1943 Sidney 16x54 Lathe Restoration

                      Comment


                      • #12
                        And RPC has delta output. Don't measure to ground or neutral. Measure across the phases. L1-l2 (incoming single phase), then L2 to T3, L1 to T3.


                        The "spec" rpm is at full load.

                        Comment


                        • #13
                          Originally posted by The Metal Butcher View Post
                          You don't really care about voltage to ground, moreso voltage between phases.

                          1810 isn't that much over spec. 1800 RPM is synchronous speed for 60hz, 1750 is the full load RPM.
                          So I check with black & red probe only between the 3 wires from motor?

                          Comment


                          • #14
                            Originally posted by lakeside53 View Post
                            And RPC has delta output. Don't measure to ground or neutral. Measure across the phases. L1-l2 (incoming single phase), then L2 to T3, L1 to T3.


                            The "spec" rpm is at full load.
                            Okay I will check in morning and report my finding.Thanks

                            Comment


                            • #15
                              Originally posted by Tundra Twin Track View Post

                              So I check with black & red probe only between the 3 wires from motor?
                              Yup. T1 to T2 (should be line), T1 to T3, and T2 to T3.

                              If you need 120v for control circuitry use a transformer off L1 and L2.
                              21" Royersford Excelsior CamelBack Drillpress Restoration
                              1943 Sidney 16x54 Lathe Restoration

                              Comment

                              Working...
                              X