Siemens Electrical Operations and Maintenance Engineer Interview Questions and Answers

Star delta controlling is a method used to reduce the starting current of induction motors.

• Star delta controlling involves initially connecting the motor windings in a star configuration for starting, then switching to a delta configuration for running.

• It is commonly used for large induction motors to reduce the starting current and torque.

• The transition from star to delta configuration is typically controlled by a mot...read more

In star delta connection, typically two contactors are used.

• In star delta connection, one contactor is used for star connection and another contactor is used for delta connection.

• The star contactor is typically rated for the current of one winding, while the delta contactor is rated for the full motor current.

• Using two contactors helps in reducing the starting current and torque in the motor.

• For example, a 3-phase moto...read more

Single line diagram for DOL is a simple representation of Direct-On-Line motor starter circuit.

• DOL starter consists of a contactor, overload relay, and start/stop push buttons.

• The single line diagram shows the connections between these components.

• The power supply is connected to the contactor, which is then connected to the motor.

• The overload relay is connected in series with the motor to protect it from overloading.

• St...read more