National Fertilizers Technician Apprentice Trainee Interview Questions and Answers

A DOL starter is a Direct-On-Line starter used to start induction motors by directly connecting them to the power supply.

• DOL starters provide full voltage to the motor during starting.

• They are simple in design and cost-effective.

• Commonly used in applications where the motor load is constant and does not require speed control.

• Example: Starting a water pump motor in a residential building.

There are various types of motors including DC motors, AC motors, stepper motors, and servo motors.

• DC motors operate on direct current and are commonly used in household appliances and electric vehicles.

• AC motors operate on alternating current and are used in industrial applications.

• Stepper motors move in precise increments and are commonly used in 3D printers and CNC machines.

• Servo motors are controlled by a feedback ...read more

There are various types of starters used in electrical engineering, such as DOL starter, star-delta starter, and soft starter.

• Direct On-Line (DOL) starter is the simplest type, providing full voltage to the motor at start.

• Star-delta starter reduces the starting current by initially connecting the motor in star configuration and then switching to delta.

• Soft starter gradually increases the voltage to the motor, reducing ...read more

Starters are used to control the starting and stopping of motors. Types include DOL, star-delta, soft starters, and VFDs.

• Direct-On-Line (DOL) starters provide full voltage to the motor at start-up

• Star-Delta starters reduce the voltage during start-up to reduce inrush current

• Soft starters gradually increase the voltage to the motor to reduce inrush current and mechanical stress

• Variable Frequency Drives (VFDs) control th...read more

Glass lined reactor shaft run out refers to the misalignment or wobbling of the reactor shaft, affecting performance and safety.

• Run out can lead to uneven wear on the glass lining, increasing the risk of damage.

• Regular maintenance checks can help identify shaft run out early.

• Using precision alignment tools can minimize run out during installation.

• Example: A reactor with a 0.5 mm run out may cause significant operationa...read more

The spark test value for glass lined reactors ensures electrical safety and integrity of the lining.

• The spark test typically involves applying a high voltage (e.g., 5000V) to check for insulation failure.

• A successful test indicates that the glass lining is intact and can prevent contamination.

• If the test fails, it may indicate cracks or defects in the glass lining, requiring repair or replacement.

• Regular spark testing ...read more