In which connection does a motor run fast, star or delta?

     A motor typically runs faster in delta configuration compared to star configuration. In a star configuration, the voltage applied to the motor is reduced, which results in a lower starting torque and a slower starting speed. In contrast, in a delta configuration, the motor is connected directly to the power supply and receives full voltage, which results in higher starting torque and a faster starting speed. Once the motor has started and is running at full speed, the star-delta starter will switch the connection back to a star configuration to reduce the current flowing through the motor and protect the electrical circuit.

     The speeds of Star connected motors are slower as they receive 1/√3 voltage. The speeds of Delta connected motors are high because each phase gets the total of line voltage.

In an electrical power system, there are two main types of connections: 

1. Star 

2. Delta.

     A star connection, also known as a "Y-connection," is a type of electrical connection where the terminals of three branches are connected to a common point, also known as the neutral point. In a star connection, the line current is equal to the phase current, and the line voltage is equal to the phase voltage multiplied by the square root of three (√3). Star connections are typically used in power transmission networks for longer distances.

     A delta connection, also known as a "triangle connection," is a type of electrical connection where the three branches of the network are connected in a closed loop. In a delta connection, the line current is equal to the phase current multiplied by the square root of three (√3), and the line voltage is equal to the phase voltage. Delta connections are typically used in distribution networks for shorter distances.

     In both star and delta connections, the voltage and current relationships between the line and phase quantities depend on the type of connection. In a star connection, the line voltage is equal to the phase voltage multiplied by √3, while in a delta connection, the line voltage is equal to the phase voltage. Similarly, in a star connection, the line current is equal to the phase current, while in a delta connection, the line current is equal to the phase current multiplied by √3.

     In terms of the amount of insulation required, a star connection typically requires less insulation than a delta connection. This is because the voltage in a star connection is lower than in a delta connection.