What is the difference between connecting "star" and " delta"

Everyone who has encountered the connection to the three-phase network of an asynchronous motor (without special training), the question arose "how to connect it". There are two main connection methods – the " star method "and the"delta method". But how do you know which method to use? What happens if these methods are combined?

Yes, it is possible to connect 3 phase motors in star as well as delta connection if you have winding ends noted well i.e R-phase : R1- coil -R2 similarly for B phase and y phase.

Now you have 6 winding ends R1,R2,Y1,Y2,B1,B2;

Delta Connection

Connect R1 and B2; This forms 1st phase

Connect R2 and Y1; This forms 2nd phase

Connect Y2 and B1; This forms 3rd phase

Star Connection

Connect R2 with Y2 and B2. This forms neutral connection

Connect R1,Y1 and B1 to their respective phases these form 3 different phases.

First of all the connection method depends on the engine itself

The motor nameplate shows the type, power, rpm, voltage, and intricate symbols

When the designation indicates 400/660V, then this motor is connected to the 400V network according to the "delta" scheme

If it is necessary to reduce the starting current of the electric motor, use a combined start. That is, with the help of switching devices, they launch according to the "star" scheme, and after its acceleration they switch to the" triangle " - usually using a time relay. But it should be borne in mind that with such a start, the torque on the shaft is significantly reduced and there must be sufficient power to start.

Otherwise, the engine may quickly fail.

Rules for "combined" start-up or how not to burn the engine?

Keep in mind that not every engine can be connected using the "combined" method. If the engine is designed so that it gains speed gradually, for example, a fan or pump, then such a start is practically no threat to it. But if the engine device when connected immediately provides an output of 70-80% of the rated power, then the connection of the "star" is contraindicated even for a short period of time.

And one more important nuance-you need to build the time relay correctly. 10 seconds to accelerate the engine is more than enough. Working on the "star" connection for too long can cause the engine to fail in a few minutes.