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number of poles on a 3phase motor?

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  • #46
    I have taken pictures of the schematics of the motor and brake. Something is not working correctly with the brake connected directly to 220v AC. I tried it two days ago and it seemed to work. Yesterday evening the brake would not release when connected exactly the same way. What I don't understand on the schematic is why they are pulling the 220v off of a transformer and not taking it directly. I can read animals and financial statements really well. Schematics not so well!


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    Location: The Black Forest in Germany

    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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    • #47
      Originally posted by old mart View Post
      Yes but there might have to be some extra relays to achieve both at the same time, I don't know if a VFD can handle both.
      Most of them can, I have a number of VFD's and they have an output that can energise a relay to power such an EM brake.
      Peter - novice home machinist, modern motorcycle enthusiast.

      Denford Viceroy 280 Synchro (11 x 24)
      Herbert 0V adapted to R8 by 'Sir John'.
      Monarch 10EE 1942

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      • #48
        Can you post the model of the vfd? I can say that 4a1, 4c1 and 4c2 will be replaced by the vfd. 4c3, the brake relay should be controlled by the vfd control relay after the correct parameters are set
        Helder Ferreira
        Setubal, Portugal

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        • #49
          The VFD is a Hitachi WL200 3phase input rated for 4KW. This morning I pulled the drum off the brake so the motor is free turning and ran the motor with the VFD. The brake on the motor is quite a big brake actually. The outside drum is the same diameter as the outside of the motor. This brake looks something like the electric brakes I had on a two horse trailer in USA.
          Location: The Black Forest in Germany

          How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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          • #50
            Now I have to program the VFD to allow my Centroid Acorn controller to control the VFD. I am not going to use the VFD at the moment to control the motor speed. I will use the gearbox and do the manually to start with now. I just want this machine to actually make some parts for me in the near future. Farm machinery doesn't heal itself! I will only use the run and stop and direction functions of the VFD. For now.
            Location: The Black Forest in Germany

            How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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            • #51
              You do know that is a DC brake?
              Shown by the Bridge rectifier.

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              • #52
                Originally posted by mickeyf View Post
                Yes, that was a very informative video. I do find myself wondering how often and why a shading coil would fail or be damaged though. any hints as to what went wrong in that particular case?
                Shading rings rarely if ever fail, the AC contactor/relay/solenoid coils are very inefficient devices.
                subsequently they run hotter than their DC counterparts, and are more prone to burn out because of this.
                Same with the shaded pole fan motor where it serves a similar use, in this case it provides the phase shift in part of the iron core WRT the main winding.
                They also are prone to run hot due to the inefficiency created.

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                • #53
                  A dc coil can be connected without the core but the ac one will burn in a few seconds. New contactor coils from some manufacturers like ABB now are multi voltage ac/dc powered. They have a microcontroller board and will reduce the input voltage to the minimum necessary. In the end, the coil is always dc powered. A dc coil voltage can be greatly reduced after the initial power up and it will stay atracted.
                  Helder Ferreira
                  Setubal, Portugal

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                  • #54
                    Originally posted by MaxHeadRoom View Post
                    You do know that is a DC brake?
                    Shown by the Bridge rectifier.
                    This is the small black box inside the motor connection box that Noitigen was asking about. THis is the label on the side. What is it? This is what the two wire for the brake attach to.Click image for larger version  Name:	bridge rectifier copy.jpg Views:	0 Size:	324.4 KB ID:	1999811
                    Last edited by Black Forest; 05-07-2022, 12:28 PM.
                    Location: The Black Forest in Germany

                    How to become a millionaire: Start out with 10 million and take up machining as a hobby!

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                    • #55
                      Looks like a rectifier

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                      • #56
                        The company I worked for had lots of AC contractors fail from shading coils falling out. These were NEMA size 3 to 5 contractors with 120v AC coil with the shading coils epoxyed in. I don't know if the glue failed from heat or vibration. In a pinch I brazed a piece of copper wire into a coil and staked it into the groove to keep the machine running until a new contactor was available. Our various models came from different factories and one of them started using contractors with dc coils, 120ac to the coil with a board to convert it to dc.

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                        • #57
                          Originally posted by Black Forest View Post

                          This is the small black box inside the motor connection box that Noitigen was asking about. THis is the label on the side. What is it? This is what the two wire for the brake attach to.
                          It shows AC in one side (RH) and DC out on the opposite side. Most brakes are DC types.
                          The diagram is a little strange, maybe do a search with the part number and see if anything shows it in detail.

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                          • #58
                            What I don't understand on the schematic is why they are pulling the 220v off of a transformer and not taking it directly.
                            I'm not 100% clear on this particular schematic, but... There appears to be a transformer with a 220V secondary and one with a 24V secondary.

                            Is the phase to phase voltage actually 220V? I would not expect that - not in North America anyway. I don't see the line voltage spelled out in the schematic. There are cases where a 1:1 transformer might be used for isolation/safety reasons, but I don't see that that would be likely here.
                            "A machinist's (WHAP!) best friend (WHAP! WHAP!) is his hammer. (WHAP!)" - Fred Tanner, foreman, Lunenburg Foundry and Engineering machine shop, circa 1979

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                            • #59
                              It looks like it shows just three terminals, with the bottom AC line connected to the (-) output terminal. That would indicate a half-wave rectifier, which would be inefficient and would cause a net DC through the output windings of the 24 VAC transformer, and would result in saturation and high current draw. The schematic shows a four terminal device, but has a single rectifier symbol. This can be easily tested with a DMM.

                              Now I see in the second image a three terminal device connected across the brake, and that would be a free-wheeling diode to conduct the stored energy in the coil when power is removed. It is labeled 4n1 and called a "Bremse".

                              It is the name of a German training ship, but can also mean "horsefly", "gadfly", or "brake". Probably the last...
                              Last edited by PStechPaul; 05-07-2022, 05:33 PM.
                              http://pauleschoen.com/pix/PM08_P76_P54.png
                              Paul , P S Technology, Inc. and MrTibbs
                              USA Maryland 21030

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                              • #60
                                You are over analyzing things a little. The device is a simple diode with an extra terminal to land wires on. The extra post is JUST a terminal for one line wire and one brake wire. The other two terminals are for A) the other line wire and B) the other brake wire.
                                MaxHeadRoom is exactly correct. The actual brake is DC and this diode module is for this type of application to provide terminals to land every wire properly.
                                To address the transformer question, I think it is there to allow for multiple mains voltage. I am not sure of voltages in Europe, but in the USA it is very common for three phase equipment to be able to operate on 230 volt 3 Ph or 460 volt 3Ph. The only change is motor wiring and transformer wiring and fuse size. It is much cheaper for manufacturing to do it this way and it keeps the equipment universal to the power available. Please do not flame me about 208 volt 3 Ph. The point is the same......
                                Robin

                                Happily working on my second million Gave up on the first

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