L t statar dol

The first step is to place wire numbers on the schematic diagram.A suggested numbering sequence is shown in Figure 29–11.The starting current is reduced to one third of the direct starting current.Due to the reduced starting torque, the star-delta-connection is suitable for drives with a high inertia mass but a resistance torque which is low or only increases with increased speed.The duration of start in star connection depends on the motor load.During delta connection, the full mains voltage is applied to the motor windings.In this example, run winding lead T1 will always be connected to L1, and T4 will always be connected to L2. When the forward contactor is energized, start winding lead T5 will be connected to L1, and T8 will be connected to L2.When the reverse contactor is energized, start winding lead T5 will be connected to L2, and T8 will be connected to L1.

For star delta starter circuit diagram,wiring technique and motor base termination, Please read my post for star delta motor connection.The rotation of the motor has to be considered as well.If wrong rotation,we should change the rotation by switch the phase.For the star delta starter, a motor must be in delta connected during a normal run and the main purpose is to be able to use star delta starter. Star delta starter only works when the application is light loaded during the start.Star delta starter received the starting current is about 30 % of the starting current during direct on line start and the starting torque is reduced to about 25 % of the torque available at a D. If the motor is too heavily loaded, there will not be enough torque to accelerate the motor up to speed before switching over to the delta position.

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