Delta-Delta Connections in Large LV Transformers

The correct answer is option 'A', which states that delta-delta connections are used in applications of large LV transformers. In order to understand why this is the case, let us delve into the details of delta-delta connections and their applications.

Understanding Delta-Delta Connections
Delta-delta connections, also known as the delta-wye connections, are a type of transformer connection where both the primary and secondary windings are connected in a delta configuration. This means that the primary and secondary sides of the transformer have three windings each, connected in a closed-loop triangular shape.

Advantages of Delta-Delta Connections
Delta-delta connections offer several advantages, making them suitable for specific applications, such as large LV transformers:

1. Simplicity: Delta-delta connections are relatively simple to implement, requiring fewer components and connections compared to other transformer configurations.

2. Balanced Loads: Delta-delta connections can handle unbalanced loads efficiently. This is because the delta configuration allows the transformer to distribute the unbalanced currents across the three phases, preventing overloading of any individual winding.

3. Grounding Flexibility: Delta-delta connections offer flexibility in terms of grounding options. The absence of a neutral connection in the delta configuration allows for different grounding schemes to be employed, such as ungrounded, grounded through impedance, or grounded through a neutral grounding transformer.

Applications in Large LV Transformers
Large LV transformers, which typically operate at lower voltages on the secondary side, often require delta-delta connections due to the following reasons:

1. Load Distribution: Delta-delta connections enable the distribution of large LV loads across the three phases, allowing for efficient power transfer and balanced operation.

2. Short Circuit Currents: Large LV transformers are designed to handle high short circuit currents. The delta configuration enhances the ability to handle these currents by dividing them among the three phases, reducing the stress on individual windings.

3. System Stability: Delta-delta connections contribute to the stability of the overall power system. They can mitigate voltage imbalances and minimize the impact of unbalanced loads, ensuring reliable and continuous operation of the LV system.

In conclusion, delta-delta connections are commonly used in applications of large LV transformers due to their simplicity, ability to handle unbalanced loads, grounding flexibility, load distribution capabilities, capacity to handle short circuit currents, and contribution to system stability.

Large no of turns are there in the delta connected system