Topic 7 interconnected star and delta devices topic b7

Bài giảng ngành Điện: Giải các bài toán trong mạch điện điện thế thấp một pha và ba pha (Phần B) gồm các chủ đề sau Solve problems in single and threephase low voltage circuits Part B Content Topic 1: AC power and power factor Topic 23: Multiphase systems Topic 4: Threephase STAR connection Topic 5: Threephase, Fourwire systems Topic 6: Threephase DELTA connection Topic 7 Interconnected Star and Delta Devices Topic 8 Energy and Power Requirements of AC Systems Topic 9: Harmonics

Solve problems in single and three-phase low voltage

circuits

Topic 7: Interconnected Star and Delta Devices

Star-Delta Configuration

 Consists of a Star-connected supply driving a Delta-connected load

 Summary

 Delta-connected load draws a HIGH phase current that translates to a HIGHER line current that impacts directly onto the phase current of the Star-connected supply (eg Transformer or alternator)

 Note: Star-to-Star configuration means voltages and

currents are the same for supply as for the load

Star-Delta Configuration

Vp

Vp Vp

L1

L2

R2

R3 Vp

Vp Vp

L1

L2

R2 R3

Delta-Star Configuration

 Consists of a Delta-connected supply driving

a Star-connected load

 Summary

 Star-connected load draws a LOW phase current that translates to the SAME line current that translates into a LOWER phase current of the Delta-connected supply (eg Transformer or alternator)

 Note: Delta-to-Delta configuration means voltages and currents are the same for supply as for the load

Delta-Star Configuration

Vp

Vp = VL Vp

Vp = VL

Interconnected Star and

Delta Devices

 Relationships

 Star-to-Delta produces a system that places HIGH current demands on the supply system.

 However, Star-connected supply allows

connection of unbalanced and single-phase loads.

 Delta-to-Star produces a system that places LOW current demands on the supply system.

 However, Delta-connected supply is very

restricted in the types of loads that can be

connected.