Which is true for delta connection?

Question

Examoogle · Accepted Answer

Option B: $V_L = V_P$

Explanation & Concepts:
In a delta ($\Delta$) connection, the three phases are connected in a closed loop such that the terminal voltage across each phase is directly equal to the line voltage. Consequently, the phase voltage ($V_P$) is identical to the line voltage ($V_L$), resulting in $V_L = V_P$.

Working Principle: In a delta configuration, each end of a phase winding is connected to the start of the next winding, forming a mesh. Because the line terminals are connected directly to these mesh nodes, the potential difference between any two line terminals is the same as the potential difference across a single phase winding. Thus, the voltage across the load or source impedance is equal to the supply voltage applied between the lines.

Key Formulas: $V_L = V_P$ — Relation between line voltage and phase voltage in delta connection; $I_L = \sqrt{3} I_P$ — Relation between line current and phase current in balanced delta load

Key Points: Delta connection is also known as a mesh connection.; The sum of currents at any node in a delta system is zero according to KCL.; Phase current is the current flowing through a single winding.; Line current is the current flowing through the supply conductors connected to the terminals.

Advantages: Eliminates the need for a neutral wire, reducing conductor material cost for transmission.; Provides a balanced path for currents in three-phase systems.

Disadvantages: Does not provide a neutral point, making it unsuitable for loads requiring different voltage levels (e.g., 400V/230V).; Sensitive to circulating currents if phases are unbalanced.

Applications: Industrial motor drives and power distribution transformers.; High-voltage transmission systems.

Additional Info: In delta systems, if one phase fails, the remaining two phases can still operate in an open-delta configuration at reduced capacity.. Option A ($I_L = I_P$) is characteristic of a Star (Wye) connected load, not a Delta connection.

Answer: B is correct — In a delta connection, the line voltage is exactly equal to the phase voltage because the terminals are connected directly across the phase impedances.

Exam Tip: Always remember the mnemonic: In 'Star' (Wye), currents are equal ($I_L=I_P$); in 'Delta', voltages are equal ($V_L=V_P$).

Examoogle · Answer

Option A: $I_L = I_P$

Feature	Star	Delta
Connection Type	Star (Wye)	Delta (Mesh)
Voltage Relation	$V_L = \sqrt{3}V_P$	$V_L = V_P$
Current Relation	$I_L = I_P$	$I_L = \sqrt{3}I_P$

Correct Answer

Discussion (0)

Correct Answer

Related Questions

Discussion (0)