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Difference in 3-Phase Motors: 230/400V vs 400/690V, Star-Delta Connection & Origin of 690V Voltage

K4ptur 61497 18
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  • #1 13968166
    K4ptur
    Level 10  
    Hello. I would like to know the difference in three-phase motors, where the rated voltage is 230/400 and 400/690 depending on the star or delta connection. I am also wondering where the voltage of 690V comes from, if the interfacial voltage is 400V, so what voltage is it 690V?
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    #2 13968226
    zibo50
    Level 17  
    The phase is 400V and the interphase is Square with 3 * 400 = 690V. The difference between these motors is the appropriate number of windings, and in particular, the voltage that must withstand the insulation of the windings.
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    #3 13968228
    fuutro
    Level 43  
    After all, a motor with 230V windings will only work in a star connection, while a motor with 400V windings will work in both star and delta (phase-to-phase voltage across the coil).
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  • #5 13968259
    lesławek
    Level 32  
    Well, like this: Each coil in the 230/400 motor is 230V, such a motor cannot be connected in a delta when powered from our network because it will burn, so for such a motor the only correct connection is a star. On the other hand, in the 400/690 motor, each coil is 400V and such a motor can be connected in a delta. It can also be controlled by a star triangle switch at start-up, but for such a motor, work in a star means 3 times less power, so you must not leave such an engine in a star, because when loaded with rated torque, it will get stuck and will also burn due to lack of cooling.

    Star delta switch? I think the triangle star ... [Łukasz]
  • #6 13968335
    Krzysztof Reszka
    Moderator of Electrical engineering  
    lesławek wrote:
    Well then: Each coil in the 230/400 motor is 230V, such a motor must not be connected in a delta when powered from our network because it will burn

    It is not true that you can connect in a delta, because such a motor will work from our network with the help of an inverter. There are many such solutions. For electricians, this solution should be obvious, for an amateur I would not write it like that.
  • #7 13968379
    fuutro
    Level 43  
    The question of what you are dealing with. Inverters are an additional device that enables miracles as opposed to an ordinary switch ...
  • #8 13968393
    lesławek
    Level 32  
    We are not talking about inverters, but about the possibilities of connecting the motor to the network.
  • #9 13968404
    Krzysztof Reszka
    Moderator of Electrical engineering  
    K4ptur wrote:
    Hello. I would like to know what is the difference in three-phase motors, where the rated voltage is 230/400 and 400/690

    Well, you need to specify it in the subject because we can write elaborates here.
  • #10 13968582
    K4ptur
    Level 10  
    I read that Poland has no 230V phase-to-phase voltage, only 230V phase and 400V phase-to-phase voltage. And now I am wondering if there is such a thing as 400V phase voltage, that is, for example, 3 phases - 400V each - and from this the 690V is created? This is where I have a problem reasoning it.

    If I have a "power" socket in my outbuilding near my house, i.e. it has 3 phases and zero, then each phase has 230V, right? In the case of the 400/690 motor, it is possible to connect it in the 690V configuration, is it not possible? Hence my question on the subject of how it all differs.
  • #11 13968599
    lesławek
    Level 32  
    It's not just that the 400/690 motor can run at 400V in a delta and at 690V in a star. 690V voltage is rarely found, as far as I know, there are such installations on ships and offshore oil and gas mining.
  • #12 13968623
    K4ptur
    Level 10  
    I understand that it is just a 400/690 motor running in a star, but then a special network is needed where the phase voltage is 400V. So if you do not have such a network in home conditions, it means that when you buy a 400/690 motor, you can only connect it into a triangle. (?)
  • #13 13968637
    lesławek
    Level 32  
    It is not necessary to start such a motor with a star / delta switch. Then the motor cuts in on the star to limit the starting current, and then delta for the rated power. This cannot be done with the 230/400 motor, because it cannot be delta-switched.
  • #14 13968942
    fuutro
    Level 43  
    Unless you give a three-phase transformer / autotransformer, but this is only an option to raise the voltage.
  • #15 13968998
    zibo50
    Level 17  
    Read any kind of engine nameplate, and then write nonsense
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  • #17 13969241
    Krzysztof Reszka
    Moderator of Electrical engineering  
    zibo50 wrote:
    Read any kind of engine nameplate, and then write nonsense

    A colleague will brighten us up.
    I think we will award a prize with my friend Fuutro,
    lesławek wrote:
    This cannot be done with the 230/400 motor, because it cannot be delta-switched.

    Not from the receiving network.
    lesławek wrote:
    690V voltage is rarely found, as far as I know, there are such installations on ships and offshore oil and gas mining.

    Let's leave the kerosene aside, the topic was discussed recently, the engine factory writes for us the information that the engine can be switched into a star, the triangle has just 6 ends.
  • #18 13969451
    K4ptur
    Level 10  
    Thanks, gentlemen, for the information, a lot has been explained to me, although sometimes it is hard to see when everyone writes something else and it is not known if it is certain information. :)
  • #19 13969958
    Anonymous
    Anonymous  
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Topic summary

The discussion centers on the differences between three-phase motors rated at 230/400V and 400/690V, particularly in relation to their connection types (star and delta). It is clarified that a 230/400V motor can only be connected in a star configuration, as connecting it in delta would risk damage due to excessive voltage. In contrast, a 400/690V motor can operate in both star and delta configurations, with the star connection allowing for reduced starting current. The origin of the 690V voltage is explained as being derived from the phase-to-phase voltage of 400V, where the interphase voltage is calculated as 400V multiplied by the square root of three. The conversation also touches on the necessity of specific network conditions for operating 400/690V motors and the use of inverters for different configurations.
Summary generated by the language model.
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