STAR TRIANGLE

Estrela Triângulo

When choosing the ET switch, it must be considered that at the moment of starting (Y) in star, the current and starting moment are reduced to approximately 1/3 of their corresponding values ​​in the direct connection. They are intended for starting three-phase motors with a short-circuited rotor.

This type of switch is used for motors whose nominal delta voltage coincides with the nominal voltage between phases of the power supply network, therefore a 220/380 Y motor cannot be connected with a delta star switch on a 380 V network between phases. It is essential for starting that the motor has the possibility of connecting to dual voltage, that is, 220/380V, 380/660V or 440/760V. Motors must have at least six connection terminals. In star connection, the current is reduced to 25 to 33% of the starting current in delta connection. The load's resistant torque cannot exceed the motor's starting torque, nor can the current at the moment of switching to delta be of an unacceptable value. There are cases where this starting system cannot be used.

Motors that have a nominal operating voltage above 660V must have a special insulation system, suitable for this condition.

They are used to start three-phase motors, with the aim of reducing the starting current, in order to limit the voltage drop in the supply line.

There are cases where, due to the characteristics of some machines, we must use this type of key. These are machines with oversized flywheels (presses in general), wire drawing machines, conveyor belts, injection molding machines, choppers, etc.

The star triangle switch in general can only be used when starting machines at no load, that is, without load. Only after reaching the nominal speed can the load be applied.

 APPLICATION:
Winches, turning presses, eccentric presses, guillotine presses, machine tools in general, agricultural machinery, civil construction and others.