WorksheetsDOL and Star-Delta Starter Quiz
Total questions: 20
Worksheet time: 10mins
In a DOL starter, the contactor is mainly used to:
Reduce voltage
Connect motor directly to supply
Control speed
Provide torque control
The overload relay in a DOL starter is used to:
Protect against overcurrent
Start the motor
Reverse motor direction
Control voltage fluctuations
The 'NO push button' in a DOL starter is used as:
Stop switch
Start switch
Emergency switch
Reset switch
The 'NC push button' in a DOL starter is used as:
Stop switch
Start switch
Overload switch
Reset switch
In a DOL starter, when the stop push button is pressed:
Motor runs at half speed
Contactor coil is de-energized
Motor continues running
Motor switches to star connection
A star-delta starter is used to:
Reduce starting torque
Increase starting current
Reduce starting current
Control motor speed
The changeover from star to delta is performed by:
Overload relay
Timer
Thermal switch
Fuse
In star connection, the motor receives:
Full line voltage
√3 times phase voltage
Line voltage/√3
Half of line voltage
The advantage of star-delta starter is:
Full torque at start
Reduced current at start
High starting power factor
Reduced slip
In a star-delta starter, interlocking is used to:
Prevent motor from overheating
Prevent simultaneous closure of star and delta contactors
Increase torque
Protect motor windings
When the motor is switched to delta connection:
Torque decreases
Motor runs at rated voltage
Motor stops
Current reduces further
The time delay relay in star-delta starter ensures:
Motor starts slowly
Motor runs continuously in star
Motor switches from star to delta after preset time
Motor stops after certain time
Jogging (or inching) is used to:
Start motor at full speed
Run motor for short intervals
Reduce voltage
Switch star to delta
The jog button is usually a:
NO push button
NC push button
Selector switch
Emergency switch
Jogging operation is achieved by:
Continuous supply to contactor
Momentary energization of contactor coil
Automatic relay operation
Thermal overload relay
Jogging is mostly used in:
Conveyor systems
Textile machines
Machine tool positioning
All of the above
In a jogging circuit, the holding contact is:
Bypassed
Short-circuited
Always open
Always closed
Jogging operation is also called:
Reversing
Inching
Braking
Plugging
During jogging, the motor:
Runs continuously at rated speed
Stops immediately after button release
Switches to star mode
Runs in reverse automatically
Jogging control circuit prevents:
Motor overheating
Motor self-holding during short run
Excess current flow
Speed fluctuations
