The contactors are smaller than the single contactor used in a Direct On Line starter as they are controlling winding currents only. The Star/Delta starter is manufactured from three contactors, a timer and a thermal overload. The selection of conductors between the controller and the motor shall be based on 58 percent of the motor full-load current. For a wye-start, delta-run connected motor, the selection of branch-circuit conductors on the line side of the controller shall be based on the motor full-load current. Please used AC 3 rating for ease refer my last post about magnetic contactor sizingĤ30.22 (C) Wye-Start, Delta-Run Motor.
#Star delta problem pdf full#
If you want motor rotation for clock-wise,the phase colors are RED,YELLOW,BLUE.But if you want anti clock-wise rotation,the phase colors are BLUE,YELLOW,RED.For star delta control wiring diagram,please refer to my post about star delta diagram controlįirst, you must know the Full Load ampere for your motor.
#Star delta problem pdf how to#
We can refer the complete wiring for star delta starter diagram below.If you want change their rotation for clock-wise or anti clock-wise,you need change two of phase ( RED or BLUE) at delta contactor.I share the technique how to change rotation in my next post. RED PHASE : U1 and W2 YELLOW PHASE : U2 and V1 BLUE PHASE : V2 and W1 So.from this formula,we must wiring the motor follow the phase color code. Why it very important?Because each manufacturing have their own style for numbering and winding motor connection. When we refer to this diagram,We can see correct terminal for the winding for each phase : *CAUTION: Please refer to the name plate of motor to confirm the winding numbering ( U1,U2,V1,V2,W1,W2 ) and the motor connection of winding. What is Star Delta connection? Star delta magic triangle This time i want share my technique when perform wiring task and connected to the star delta stater for induction motor.ĭon`t worry,it simple and easy if we understand the basic concepts.I explains detail step by step how to do it :D From this triangle diagram,we can determine the correct phase,cable termination for right terminal and the rotation.As we know,the star delta stater is so tricky if we not fully understand the concept and their method. The motor needs to be connected in delta to run at full load / power.For star delta stater,the motor connection must have 6 cables from control panel and 6 terminals at induction motor ( U1,U2,V1,V2,W1,W3).To wiring the motor connection for star delta starter,the important thing that we must fully understand is about the basic of STAR DELTA MAGIC TRIANGLE.įor detail about star delta stater please read my last post about it.
As the VFD cannot generate a DC bus above the peak voltage of the input, you can never get 380v out of a 220v input.
Small motors, for which these VFDs where designed for are generally connected in star. Very often I get a query that they cannot get the motor up to full load without exceeding the name plate data. In closing, there are single phase inputs to three phase variable frequency drives (VFD). In summary, you can put any voltage onto a motor as long as it does not exceed the insulation level and the current limitations of that particular motor. Setting up the protection is tricky and safety first, please. The efficiency and power factor will NOT be as per design and you must understand this. We have run 380v on 525v and vice versa in an emergency. As most insulation that goes into motors is rated at 1000v plus, the voltage is not a problem until the impedance gets low enough to exceed the current limitation on the conductors to a point where the temperature will destroy the insulation.
The current is controlled by the impedance of the circuit and the load on the motor. The flux density (dependent on many things) is a function of the current and voltage. Going back to basics it is the current driven by the voltage that creates the flux. Of Couse all 6 motor windings must be accessible.Īs stated above, you can take a 380v, 3 phase star connected motor and run it as a 220v, three phase delta connected motor. If the motor is rated at 380V - 'delta connected' then it could be connected in star or delta as connecting a 380V delta rated motor in star will reduce the voltage across the windings to 220V which is OK and often used in Star/Delta starting to reduce start up current. Note that in star, each winding gets root3 of the applied voltage (or 380/1.732) connecting in delta means that each winding get the phase-phase voltage EG 380V. That would be the equivalent of applying 380 volt to 220v windings so clearly the motor would fail. If the motor is designed to run in star a 380V 3-phase power supply, then it cannot be connected in delta on the 'same' supply.
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