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number of poles on a 3phase motor?

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  • Black Forest
    replied
    Gentlemen, I used ignorant in my post to be kind to myself but in reality I am probably stupid! Though I might not be stupid because I know I am dumb so that at least makes me one step ahead of the truly stupid because they don't know they are stupid.

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  • PStechPaul
    replied
    Perhaps instead of "ignorant", use the term "uninformed". There is also "willful ignorance", which may be worst of all.

    What's the difference between ignorance and apathy? I don't know, and I don't care.

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  • Bob Engelhardt
    replied
    Originally posted by rdfeil View Post
    ...
    the only dumb or stupid question is the one not asked. Now when I get asked the same question many times by the same person I begin to wonder about my last statement......
    Yeah, "No stupid questions" is just too glib. There are stupid questions. As there are stupid people, who can be expected to ask stupid questions. Even unstupid people can ask stupid questions, in a moment of mental fog.

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  • Lew Hartswick
    replied
    Yea There is so much BAD education these days the term gets used inappropriately, like so many other words. :-(
    ...lew...

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  • rdfeil
    replied
    Originally posted by Lew Hartswick View Post

    There is nothing wrong with "Ignorance" , it is easily corrected by education. The real problem is "Stupidity", it, UN-fortunately seems to be permanent. :-)
    ...lew...
    Lew Hartswick , I agree 100%, but I dislike the word ignorance as it seems to be used WAY to much. I always stand by the opinion that the only dumb or stupid question is the one not asked. Now when I get asked the same question many times by the same person I begin to wonder about my last statement......

    Leave a comment:


  • Lew Hartswick
    replied
    Originally posted by rdfeil View Post

    No problem Black Forest . It is not ignorance it is simply not your specialty
    There is nothing wrong with "Ignorance" , it is easily corrected by education. The real problem is "Stupidity", it, UN-fortunately seems to be permanent. :-)
    ...lew...

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  • rdfeil
    replied
    Originally posted by Black Forest View Post

    Thank you for explaining it so this ignorant guy could understand it.
    No problem Black Forest . It is not ignorance it is simply not your specialty so you do not know the details. Another thing that made some of us stumble are the terms used. In the US the three phase voltage is refered to by the phase to phase voltage not the phase to neutral voltage. You did the best thing... You asked a question! The answers bounced around a bit, but that is the nature of a forum. Sorting the information is a skill to be proud of 😁.

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  • Noitoen
    replied
    Originally posted by MaxHeadRoom View Post
    My point was the brake connection was marked 220v~ ?
    They mention the voltage to feed the brake. The motor is 380v, 3 phase star and you can connect to one phase and the star connection or 220v 3 phase delta and again you connect the brake to two of the supply phases. In both cases the brake's rectifier will receive 220v~.

    In reality the brake is around 100 VDC that is the result of the half wave rectifier's output. The manufacturer doesn't feel the need to mention this detail but itΒ΄s usually stamped on the brake coil's casing.

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  • MaxHeadRoom
    replied
    Originally posted by Noitoen View Post

    The rectifier is in the motor connection box so you must feed 220v~ to those wires
    My point was the brake connection was marked 220v~ ?

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  • Black Forest
    replied
    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 πŸ˜€.
    Thank you for explaining it so this ignorant guy could understand it.

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  • rdfeil
    replied
    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 πŸ˜€.

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  • Noitoen
    replied
    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.

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  • Noitoen
    replied
    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

    Leave a comment:


  • PStechPaul
    replied
    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.

    Leave a comment:


  • Noitoen
    replied
    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.

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