A star connection can be easily accomplished simply by bridging one of the two horizontal rows in the connection box of the motor. The other ends of the coils are connected together in a common point. In a star connection, each one of the 3 phases (R-S-T) is connected at one end of each coil. Suppose for example that the motor is connected in Star. A permanent connection is accomplished with 2 or 3 metallic bridges. This is usually done if the motor is small (smaller than 3.5 KWatts) or if the motor is driven by an inverter or some kind of electronic driver. A permanent connection is when the motor is connected in either Star or Delta, and this connection is not supposed to changed during the operation of the motor. The answer is simple: To easily bridge a permanent connection. You may now wonder, why the coils are connected in cross-pattern and not vertically. Instead, the pairs are in cross-pattern like this: It sounds logical to separate these 3 pairs in a vertical pattern, but that's not the way it goes. Since each coil has 2 endings, it is easy to understand that these six leads can be separated in three pairs, and each pair is connected to one coil. Here is a photo from a typical electrical connection box:Īs you can see, there are indeed six leads arranged in two rows. First of all, you need to understand how the coils are connected with the six motor leads that exist in the electrical connection box.
Ac motor winding how to#
If someone works with AC 3-phase motors, then it is important to know how to connect these motors in Star and Delta connection, and how to detect an electrical problem. It is called squirrel-cage, because it's rotor looks like the exercising wheel found in squirrel or hamster cages.Ī typical 3-phase squirrel-cage motor has six connection leads in the electrical connection box for the three coils. The most common type though is the -so called- squirrel cage rotor. Thank you for your attention.The rotor of a squirrel-cage motorThere are several different AC motor types, each one with different operating and mechanical characteristics.
If you have any questions please ask, and i will try to answer ass soon as possible. I hope you enjoined my presentation of rewinding a three phase motor. I took all electrical equations and orientation tables from book: Neven Srb ELEKTROMOTORI If we compare all data we can see that motor isn't bad at all. In second line is measurement at 380V and third line at 400V. In upper table there is data from manufacturer in first line. Motor was made for voltage 380V, but now we have 400V in EU. I made all tests with two different voltages. But in next measurement we can see that resistances do not dramatically affect on electric motors performance. You can se that on measurment of resistance where, winding resistances aren't identical. Because gap between stator and cover was very small, i decided to do a little bit bigger first coils, and a little bit smaller last coils. This time winding was too big and i couldn't close the cover of motor. Then i decide to make bigger one but i found problem again. I couldn't access to them because other winding were too small. First i made coils too small, and i couldn't insert last coils in slots. I had a lot of problems with winding new winding too. I had a lot of problems with calculation but i solved them and i got same parameters of winding as were on old one. Most time i spent on calculation of new winding. It took me about a week to rewind this motor.
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