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  1. EngRepair

    Concentric to Lap Winding Conversion

    Several examples from a publication on how to convert a three-phase concentric winding to a double-layer lap winding are found online. The displayed table shows the value of the conversion factor in the case of a 54-slot, 2-pole, mixed winding ( 30 coils in total) with pitches of 1-20, 22, 24...
  2. EngRepair

    Permissible flux density of transformer core

    Hi, prc, Thank you for the quick response. I have to admit that from the given formula, I don't see a clear relationship between power and the cross-sectional area of the core. Also, I wonder if the formula for transformer power should include the cross-sectional area of the core window. Could...
  3. EngRepair

    Permissible flux density of transformer core

    Thank you all for the very helpful advice. There is one more thing I should ask since I have found quite different recommendations in the books. It concerns the relationship between the cross-sectional area of the core and the power of the transformer. Is there any reliable formula...
  4. EngRepair

    Permissible flux density of transformer core

    I would need advice from esteemed experts on this forum. It concerns the custom design of a dry, low-voltage power transformer with an approximate power rating of 1 to 3 kVA. The issue at hand is that we have several sizes of new "EI" transformer cores of unknown quality and manufacturer, in...
  5. EngRepair

    32-pole motor winding with 96 slots

    The pitch is 1-6. (Btw, I came across this diagram looking for an option to redesign the motor (96 slots, 8 poles) to the highest possible number of poles.) Apparently, it's consequent pole winding with extended pitch and I really don't know why pitch 1-6 was chosen. As for the standard winding...
  6. EngRepair

    32-pole motor winding with 96 slots

    4 circuits. It should work but at first glance seems to me that half of the coils are wasted because of the extended pitch. Pay attention to all the slots where the coils are marked with the same color. Current flows in opposite directions, and there is no torque contribution from these coils...
  7. EngRepair

    32-pole motor winding with 96 slots

    Does anyone else see something very strange in this unusual diagram? It is a three-phase, double-layer 32-pole motor winding with 96 slots. Is this connection correct? If so, are there any benefits?
  8. EngRepair

    Consequences of increasing the length of the iron core in electric motor

    Hi, Electricpete, I'm quite surprised if you're not recognizing that this is the same question, not a new one. I have some experience as a winder, but I'm not particularly fond of theory. Additionally, I didn't see any specific answers to my last, very straightforward questions. So, could you...
  9. EngRepair

    Consequences of increasing the length of the iron core in electric motor

    I will try to add a couple of questions (instead of answers) that simulate this situation and maybe make this puzzle easier to solve. Let's consider an original submersible pump motor with a power rating of 60 HP, where we will replace only the winding according to the original winding data of...
  10. EngRepair

    Consequences of increasing the length of the iron core in electric motor

    The old pump has already been repaired and returned to the customer. The spare pump will eventually be used in another place, with a lower HP requirement. That's what the customer decided. By the way, in brief, I had asked the same question elsewhere and was told: Increasing the length of the...
  11. EngRepair

    Consequences of increasing the length of the iron core in electric motor

    In fact, this is not a purely hypothetical scenario. One of our customers brought a submersible water pump to our service for repair, which worked successfully for a long period of time. At the same time, the customer had the intention of replacing it with a new spare pump from their warehouse...
  12. EngRepair

    Consequences of increasing the length of the iron core in electric motor

    Unfortunately, I did not receive the expected response. If you read carefully what I wrote, the question is clear and there is nothing nebulous about it. Please read my post again. What is not clear? The new motor would work on the same machine and the same load.
  13. EngRepair

    Consequences of increasing the length of the iron core in electric motor

    Hypothetical, theoretical question about electric motors. Let's say we have a fully functional three-phase squirrel-cage LV motor. Let's imagine we made another one with exactly the same geometry of stator and rotor lamination, exactly the same winding (turns/coil, wire size, pitch, etc...). The...
  14. EngRepair

    VFD on 230V 50Hz single-phase power source to drive 400V 50Hz three-phase IM load

    Perhaps something like that: https://www.youtube.com/watch?v=oDI1YxDDEB8
  15. EngRepair

    110kW LV Motor Unbalance current

    You do not have to worry as long as the current is below the rated value. Very often the currents differ due to various winding imperfections. Different resistances of phase windings are the most common imperfection of windings, not because of different number of turns per phase, but rather...
  16. EngRepair

    3Ph, 1.5HP Inductor Motor Running at Low Speed

    Try another tachometer.
  17. EngRepair

    Two-speed stator with wound rotor

    It sounds strange, but several times this type of crane motor arrived in our workshop (mostly just the stator). The stator is a two-speed motor 8 and 4 poles, constant HP connection but the rotor has an 8-pole winding. Costumer claims that the motor runs at low speed with rotor resistances...
  18. EngRepair

    Calculating a 3 phase motors mains input power

    At full load kVA = 20*0,746/(0.9*0.85)=19,5 kVA
  19. EngRepair

    Micromotor repair

    Nr. 6 is also ball bearing. They could be the ceramic type.
  20. EngRepair

    Micromotor repair

    Thanks, RedSnake, It's a lot like my case. It may even be the same manufacturer. The rotor appears to be a squirrel-cage type. Is this motor rewindable at all? It would be nice to hear from someone who has already had the opportunity to disassemble motors like this.

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