How to connect a star-delta motor

One of the weighty drawbacks of high-power asynchronous electric motors is their "heavy" start-up, which is accompanied by huge initial currents at this moment. As a result, a large voltage surge occurs in the network. Such "dips" can adversely affect the operation of electronics or other electrical units operating on the same line. For a smooth start, use the star-delta switching circuit. In which, at the beginning of the start, the engine is turned on by a star, and when the motor shaft spins up to working speed, the electronics switches it to a triangle circuit. I will show you how to assemble the starting and control unit, which will not only control the engine start and stop, but also when starting will change the scheme of its inclusion.

It will be needed

To connect, we need:
  • 3 starters, to control the power unit;
  • prefix withtime delay - adjustable time relay;
  • 2 consoles with normally open and closed contacts;
  • start and stop buttons;
  • 3 bulbs, for a clear view of the operation of the starter;
  • single-pole circuit breaker.
How to connect the engine according to the star-delta scheme

Scheme

The connection is made according to a previously drawn scheme.
How to connect the engine according to the star-delta scheme
The diagram shows the power unit and the control circuit.The power unit consists of:
  • input circuit breaker;
  • 3 powerful starters that control the star-delta power circuit;
  • electric motor.
How to connect a star-delta motor
When turned on, the first and third starters work, and when turned on, the first and second starters work. Due to the lack of connectivity to the 380 V network, we confine ourselves to a visual examination of the operation of the system without engines.Control circuits include:
  • single-pole circuit breaker;
  • start and stop buttons;
  • three starter coils;
  • normally closed contact;
  • normally open contact;
  • time relay contacts.
How to connect a star-delta motor
Putting together a circuit to demonstrate how an automatic system works.
How to connect a star-delta motor
In parallel to the starter coils, signal lamps are connected so that you can clearly see the work.

System check

Turn on the automatic switch, thereby supplying power to the entire circuit. Press the "Start" button to start the electric motor. And we have attracted the first and third starters, light bulbs 1 and 3 lit up - meaning that the engine is turned on according to the “star” scheme.
How to connect a star-delta motor
After some time, a timer is triggered, the first and second starters are attracted, and lights 1 and 2 light up - which means the motor is connected in a "triangle" circuit.
The time on the console can be adjusted from 100 milliseconds to 40 seconds. depending on how fast the engine is gaining momentum.
How to connect a star-delta motor
Press the "Stop" button and everything stops. When connecting a motor, consider connecting the motor phases. In this case, phase A arrives at the beginning of the winding, phase B comes to the end of the winding. Phase B should start at the beginning of the second winding, phase C should arrive at the beginning of the second winding, phase C should start at the beginning of the third winding, and phase A should arrive at the beginning of the third winding. br>

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