Motor Starters Flashcards
IEC motor labels instead of T1,T2,T3
T1, T2, T3, T4, T5, T6
U1, V1, W1, U2, V2, W2
Rotary phase converter
Looks like induction motor without shaft. Does not drive a mechanical load
High capacitance electrolytic capacitor applies leading current to start motor generator
Rotary phase convert can supply multiple motors?
Yes, the largest should be started first
An across the line magnetic motor starter requires a disconnect or not?
Separate disconnect means on line side of starter
Wye-delta starter requirements and stats
•6 leads
•33.3% starting compared to same motor in delta
•Inrush current 1/3 compared to delta
Single voltage / dual voltage number of leads
6 single
9 dual
Clockwise at the shift of motor is Nema or IEC?
Clockwise is Nema
Counter clockwise IEC
Full voltage manual and magnetic initial starting current % and starting torque %?
Starting current 500-600%
Starting torque 150%
Reduced voltage starters cons?
They can reduce inrush current but also reduce starting torque
Full voltage starting (across line starters) pros
•Produce high starting torque
•produce high rush current
Part winding starters and motors … what does it do? And what good for ?
2 or more sets of windings
•only one energized at full voltage to start motor
•then energizes both windings in parallel
• good for small loads to no loads
Part winding starter
When first started ?
Impedance is higher and inrush current lower
•inrush current reduced to 60-65%
Auto transformers starter need to know ?
•Current is proportional to starting voltage
•line current proportional to square start voltage
•start torque proportional to square start voltage
Part winding Taps
Starting torque 80, 65, 50%
Starting voltage 64, 42, 25%
Auto transformer starter transition .. closed and open
•Closed transition offer better performance
•maintain current through windings during transition from reduced to full voltage
Rotary phase converters are same basic construction as ?
Three phase motor
Wye delta starter reduce start voltage and start current to?
Start voltage 58%
Start current 33%
WRIM compared to SCIM with equal hp rating will have a reduced or increased starting current ?
Reduced starting current
Which phase converter is best for variable loads ?
Rotary phase converter
Starting current of a motor is reduced proportional to?
Reduced starting voltage
