#Connecting_Star_Delta_circuit, 3 phase electric motors are used in various industrial fields.
We know that every large 3-phase motor needs a dedicated circuit to reduce the value of the starting current, and this circuit is called a star-delta circuit.
Where we use the star circuit only to reduce the value of the motor current at the moment of starting, while the delta circuit we use to start the motor permanently until the motor is disconnected from the mains.
Information about connecting the star delta circuit
In the beginning, the external connection points of the 3-phase electric motor must be identified, as the motor contains six terminals connected either in the form of a star or delta.
The engine from the inside contains three coils, each file has a start end and an end end, and the beginning ends are symbolized as follows: (U1,V1,W1), and the ends are symbolized as follows: (U2,V2,W2).
In the case of the delta, the electricity source is connected to 3 phases over the beginnings or ends. While a star circuit connects the ends of the ends together with a metal conductor and connects the current source with the beginnings, and it is possible the opposite, i.e. the beginnings are combined together and the current source connects with the ends.
Why is a star-delta circuit connected?
Because the star circuit works to reduce the start-up current only at the moment of operation, while the delta circuit gives the motor the full speed so that the motor runs in its normal form throughout the continuous operation time.
Important note:
Motor manufacturers specify 3 phase voltage and current, star circuit and delta circuit, and the most common voltage values are 380V/660V or 220V/380V, and the delta voltage is always less than the star voltage, while the star current is less than the delta current.
How to choose contactors and overloads:
The main contactor K1 and the delta contactor K3 are chosen on the basis of the motor current strength and it works on a curtain connection, because the current in the delta case is distributed to the contactors (K3, K1).
The K2 star contactor is selected based on the motor current and it operates in delta division 3 (delta/3 current).
As for the overload, it can be connected directly to the current source after the fuses so that it is calibrated to the delta current.
It can also be connected below the main contactor K1 to be calibrated to a star current.
Parts used to connect the star-delta circuit
Three contactors (star contactor / delta contactor / main contactor).
Overload.
Three fuses. major.
3 phase electric motor.
On-delay.
Auxiliary points for contactors (open and closed points).
Power key and disconnect key.
Explanation of the star-delta circuit connection
When the power source is connected to a 3-phase power and control circuit, the circuit does not start the motor immediately, except after pressing the start key by hand.
The current in the control circuit then passes through the contacts of the overload, the stop switch and the ignition switch to feed the timer K1T.
Simultaneously with the timer feeding current also passes to the star contactor coil K2 through the closed timer contact and the closed delta contactor contact K3.
The current also passes through the open point K2 to feed the coil of the main contactor K1, causing the connection of the open point K1 connected in parallel with the point K2, thus the main contact points of the contactor K1 and the delta contactor are connected.
After the timer counting ends, it changes its contact points, so the circuit is converted from star to delta by disconnecting the current from the star contactor K2 coil and connecting the delta contactor K3 while keeping the contactor K1 connected without any change in its contacts. It is connected without any change in its contact points.
In the event of any failure, the overload disconnects the main and auxiliary contacts, the current from the control circuit and the power together to stop the engine from rotating.
Important note: You can connect signal lamps to show the status of the connection, the normal disconnection, and the disconnection due to a fault in the circuit.
Three-phase motor connection methods
3D motor connection methods
Three-phase motor connection methods Star, Delta or Star Delta.
Automated control cycle. Explanation of the star-delta circuit connection.
Automated control cycle. Explanation of the connection of the three-phase motor.
Automated control cycle. Connect the engine star or delta.
11 сен 2024
