The document discusses single-phase and three-phase power supply systems, outlining their configurations, applications, and efficiency. Single-phase systems use one AC waveform and are suitable for residential applications, while three-phase systems utilize three waveforms and are more efficient for industrial use. Key distinctions include the number of wires, voltage levels, and the relationship between line and phase values in each system.

1. JAI HIND
Virendra Kumar Maurya
Assistant Professor
CAEHS COLLEGE ,MEERUT
Subject- Applied Physics
Topic- AC circuits - Single phase & Poly-phase power supply
& with connection, application, relation between phase and
line voltage.

2. Single Phase and Poly-phase Power Supply
• Electric power systems can be classified into
single-phase and poly-phase (commonly
three-phase) systems.

4. Single-Phase Power Supply
A single-phase power supply uses one alternating current (AC)
waveform to deliver power.
 Number of Wires: Typically consists of two wires: a live (hot) wire
and a neutral wire. A third wire (ground) may be present for safety.
 Waveform: A single sinusoidal wave.
 Voltage: Commonly 120V or 230V, depending on the region.
 Applications: Used in residential and small commercial setups to
power lights, fans, and small appliances.
 Efficiency: Less efficient for transmitting power over long distances
compared to three-phase systems.
 Load Capacity: Suitable for low-power devices and loads.

6. Advantages:
 Simpler and more cost-effective.
 Easier to maintain and install.
 Sufficient for small-scale power needs.
Disadvantages:
 Cannot efficiently handle high-power loads.
 Voltage fluctuation is more noticeable under varying loads.

7. Three-Phase Systems
• A three-phase system is a method of electrical power generation,
transmission, and distribution that uses three alternating currents
(AC), each with the same frequency and amplitude but 120° out of
phase with each other. This system is more efficient and reliable
than single-phase systems for supplying power to large loads.

9. Three-Phase Systems
• Three Waveforms:
– Three sinusoidal voltage or current waveforms, each separated by
120°.
– Provides continuous power with smoother operation compared to
single-phase systems.
• Efficiency:
– Requires less conductor material for the same power transmission.
– Balances the power load across phases, reducing energy losses.
• Applications:
– Widely used in industrial, commercial, and high-power equipment
such as motors, transformers, and heating systems.

10. Three-phase systems can be connected in two primary
ways
Star (Y) Connection Delta (Δ) Connection

11. 1. Star (Y) Connection
• Configuration:
– One end of each phase winding is connected to a common point called
the neutral.
– The other ends are connected to the three-phase lines.
• Characteristics:
– Four wires: three-phase conductors and one neutral wire.
– The neutral allows for single-phase loads in addition to three-phase
loads.
• Voltage Relationship:
– Line Voltage (VL​
) and Phase Voltage (VP​
) are related as:
VL=√3 V
⋅ P
– Line Current (IL​
) equals Phase Current (IP):
IL=IP

13. 2. Delta (Δ) Connection
• Configuration:
– Each phase winding is connected end-to-end, forming a closed
loop.
– No neutral wire; only three wires connect to the external
circuit.
• Characteristics:
– Commonly used in industrial systems for motors and heavy
machinery.
• Voltage Relationship:
– Line Voltage (VL​
) equals Phase Voltage (VP​
): VL=VP
– Line Current (IL​
) and Phase Current (IP​
) are related as: IL=√3 I
⋅ P

15. Advantages of Three-Phase Systems
– At least one phase is always delivering power,
ensuring smoother and more efficient operation.
– Reduces overheating and power losses in
transmission.
– Can handle larger loads effectively, making it
suitable for industrial use.

16. Applications
• Industrial Power: For running heavy
machinery, motors, and equipment.
• Power Transmission: Used in power grids for
efficient long-distance electricity distribution.
• Commercial Use: Supplies energy to high-
demand buildings, such as shopping malls and
hospitals.

17. Summary
Feature Single Phase Three Phase
Waveforms One sinusoidal wave
Three sinusoidal waves,
120° apart
Voltage Levels 120V or 230V 208V, 400V, or higher
Number of Wires Two or three Four or five
Applications Residential, small loads Industrial, high-power
loads
Efficiency Lower efficiency Higher efficiency
Installation Cost Lower cost Higher cost

18. Relationship Between Line and Phase Values
Connection Type Line Voltage (VL) Line Current (IL​
)
Star (Y)
VL= √3.VP IL=IP
Delta (Δ) VL=VP IL=√3.IP

19. Sinusoidal
• A sine wave, sinusoidal wave, or sinusoid
(symbol: )
∿ is a periodic wave whose
waveform (shape) is the trigonometric sine
function.
• A sinusoidal waveform alternates between
positive and negative peaks around a central
axis (zero line). The pattern is symmetric,
indicating the energy flows cyclically in both
directions in AC systems.

20. Sinusoidal
Your (HW)😍

21. Thank You