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  • #61
    What I don't understand is why use a transformer at all for the brake? Our electricity is 220v with my 3phase consisting of 3 legs of 220v coming into the property. Why didn't they use just one leg of the 220v and go direct to the brake? Why use the transformer as a source for 220v ac to the brake? What is different about the 220v coming out of the transformer to the line 220v?
    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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    • #62
      Black Forest , I do not know the power system in Germany. When you say 220 on one line how is that referenced? What I am asking is to measure 220 volts AC with a meter, where would you connect the meter probes? The schematic you show shows the transformer connected between two of the line wires. If this were measured would it be 220 volts AC or would it be higher? In the US it could be 230, 208 or 460 volts depending on the three phase power service. Machines for the us power system often have transformers like your schematic show for a couple of reasons. First being compatible with different power systems without special builds. The second is eliminating the need for the fourth power wire or neutral in US systems. Industrial US three phase power, phase to neutral power connection is not always available. To answer your question, if the line to line voltage is 220 volts, I see no reason it would not work. Voltage is voltage. The only thing a transformer does is change voltage AND isolate primary (source) from secondary (load).

      Added: I tried to do some research on German power systems and found what may be the reason for the transformer. What I found is the German consumer power system is what we in the USA would call a 400 volt three phase system. I do not quite understand this as the math does not quite work if the system is like the US system. The information I found says that German power is 230 volt for single phase and 400 volt for three phase. If this is the way it works, then according to the diagram provided the transformer converts the 400 volt line to line voltage to the 220 volts needed for the brake. As I am unfamiliar with German power this may be all wrong, so DO NOT BANK on what I have said.
      Last edited by rdfeil; 05-08-2022, 06:16 AM.
      Robin

      Happily working on my second million Gave up on the first

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      • #63
        Between line and neutral you have 230V, between line and line you have 400V.

        To run a motor you only need the Three phases, neutral is often ommited hence if you have something that needs 230V you use a transformer(400-230).

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        • #64
          In the schematic with the transformers the PE ground is connected to one leg coming out of the transformer and goes to the brake, that is OR1. The 220v coming out of the transformer is also running to the brake, R1A. Is it right that connecting L1 230v AC and then neutral (as in just like plugging in a 220v desk lamp for instance) is not the same?
          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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          • #65
            Originally posted by Noitoen View Post

            These are 2 different things. VFD without resistor can inject a dc voltage on the windings and it will stop the motor almost instantly but then it released. the electromagnetic brake on the other hand will keep it stopped
            Not quite - The "brake" in a VFD uses the motoras a generator and turns the power created in the motor into heat. Not a full brake, but generally good enough.

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            • #66
              Originally posted by CountZero View Post
              Between line and neutral you have 230V, between line and line you have 400V.

              To run a motor you only need the Three phases, neutral is often ommited hence if you have something that needs 230V you use a transformer(400-230).
              The wires for the brake run out to the cabinet separate from the three wires for the 3phase motor.
              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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              • #67
                Isn't that 24vac transformer secondary for the brake?

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                • #68
                  Originally posted by MaxHeadRoom View Post
                  Isn't that 24vac transformer secondary for the brake?
                  No. The 24v transformer is for the three axis brakes that use 24v DC. The transformer that takes L1 & L2 input and outputs 220v is for the spindle brake.
                  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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                  • #69
                    The strange thing is the Bremse (Brake) is marked 220v ~ ,the tilde indicates AC??
                    But there is the rectifier symbol in circuit?

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                    • #70
                      All the parts you already have. The rectifier is the part 4n1 in the schematic. It must be powered from one phase and neutral in this case .

                      Power in Europe comes in 4 wires plus ground. For three phase equipment we can use a 4 pole plug with 3 phases and ground or 5 pole plug with neutral as well. The earth wire connection varies from country to country. In Portugal we have service ground and protection ground where there is 2 separate ground electrodes, one for the neutral wire of the power transformer which is star connected and another for the ground wire itself. Because of this, a short circuit of a phase to ground will have the current limited by the resistance between the 2 electrodes mentioned earlier. Because of this thicker power cables will have the cross section of the ground and neutral wire half of the cross section of the phase cables.
                      In Germany they use a common electrode for the neutral and ground which means that a short circuit will have no current limitations so the ground wire must be of the same cross section.


                      Back to the brake. Usually they are connected between the star connection of the motor and one phase. When the motor is powered there will be 230v between the star connection and the phase.
                      Some heavily loaded motors like winch motors or with some kind of flywheel, the inertia when you disconnect the motor will turn the motor in a generator that will keep the brake powered and the braking power will be unpredictable. Because of this, the brake is controlled by some separate relay contacts.

                      This seems to be the case of @Black Forest's motor
                      You may only view thumbnails in this gallery. This gallery has 1 photos.
                      Helder Ferreira
                      Setubal, Portugal

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                      • #71
                        R1A and 0R1 are 220 VAC, and go to the brake through the three terminal device marked with a single rectifier symbol. If the brake itself is DC, then that rectifier must supply half-wave rectified DC to the brake.

                        The transformer primaries connect to the three phase line-to-line, which would be 381 VAC if L-N is 220 VAC. 400 VAC L-L corresponds to 231 VAC L-N. For the USA standard, 120 VAC L-N corresponds to 207.8 volts L-L. The voltage designations are nominal, but in the US, household AC voltages have actually increased somewhat, from 110/220 to 117/234 and now 120/240, and it is not unusual for actual voltage to read 125 VAC and even 130 VAC.

                        For many electronic loads, particularly those with switching supplies, higher voltage actually enhances efficiency because current decreases for a regulated output voltage. Some motors may also run more efficiently on higher voltage, perhaps because the higher power allows the work to get done quicker and the savings are a result of lower duty cycle, or less time spend bogged down. And heaters will also run at shorter duty cycle to maintain a set temperature.

                        However, incandescent lamps will draw more current at higher voltage and lifetime will be reduced, but they will also run more efficiently due to higher lumen output with whiter light. My father said that, in the early days of electrification, you could take your burned-out bulbs to the power company and they would replace them free.
                        http://pauleschoen.com/pix/PM08_P76_P54.png
                        Paul , P S Technology, Inc. and MrTibbs
                        USA Maryland 21030

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                        • #72
                          Originally posted by MaxHeadRoom View Post
                          The strange thing is the Bremse (Brake) is marked 220v ~ ,the tilde indicates AC??
                          But there is the rectifier symbol in circuit?
                          The rectifier is in the motor connection box so you must feed 220v~ to those wires
                          Helder Ferreira
                          Setubal, Portugal

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                          • #73
                            Originally posted by PStechPaul View Post
                            R1A and 0R1 are 220 VAC, and go to the brake through the three terminal device marked with a single rectifier symbol. If the brake itself is DC, then that rectifier must supply half-wave rectified DC to the brake.

                            The transformer primaries connect to the three phase line-to-line, which would be 381 VAC if L-N is 220 VAC. 400 VAC L-L corresponds to 231 VAC L-N. For the USA standard, 120 VAC L-N corresponds to 207.8 volts L-L. The voltage designations are nominal, but in the US, household AC voltages have actually increased somewhat, from 110/220 to 117/234 and now 120/240, and it is not unusual for actual voltage to read 125 VAC and even 130 VAC.

                            For many electronic loads, particularly those with switching supplies, higher voltage actually enhances efficiency because current decreases for a regulated output voltage. Some motors may also run more efficiently on higher voltage, perhaps because the higher power allows the work to get done quicker and the savings are a result of lower duty cycle, or less time spend bogged down. And heaters will also run at shorter duty cycle to maintain a set temperature.

                            However, incandescent lamps will draw more current at higher voltage and lifetime will be reduced, but they will also run more efficiently due to higher lumen output with whiter light. My father said that, in the early days of electrification, you could take your burned-out bulbs to the power company and they would replace them free.
                            I've made many replacement rectifiers for brakes like that. They are just 2 diodes with their cathodes connected together to make the positive output with a protection varistor in parallel with each diode. Diode 1 anode connects to the phase and is the rectifier and diode 2 anode connects to the neutral and the negative of the load and acts as a freewheel diode. The positive is the cathodes of the 2 as mentioned earlier.
                            Helder Ferreira
                            Setubal, Portugal

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                            • #74
                              Ok, this is just like the US power system, only at different voltages. Back to Black Forest 's question about connecting the brake to 220 volt line voltage. YES, it will work just fine. The only thing different from your drawing is that you will have to have the Neutral wire and the brake will be connected between the Neutral and any Phase wire through a relay or Acorn Board relay which is activated when the spindle is turned on. This is exactly like industrial equipment in the US. Three phase power wires (3) and one ground/PE wire (1). In your diagram you only have 400 volts available (Phase to Phase voltage). The brake requires 220 volts so a transformer was required. Simple as that 😀.
                              Robin

                              Happily working on my second million Gave up on the first

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                              • #75
                                Originally posted by rdfeil View Post
                                Ok, this is just like the US power system, only at different voltages. Back to Black Forest 's question about connecting the brake to 220 volt line voltage. YES, it will work just fine. The only thing different from your drawing is that you will have to have the Neutral wire and the brake will be connected between the Neutral and any Phase wire through a relay or Acorn Board relay which is activated when the spindle is turned on. This is exactly like industrial equipment in the US. Three phase power wires (3) and one ground/PE wire (1). In your diagram you only have 400 volts available (Phase to Phase voltage). The brake requires 220 volts so a transformer was required. Simple as that 😀.
                                Thank you for explaining it so this ignorant guy could understand it.
                                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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