In an open wye-delta connection, the neutral on the primary side and the supply source for the primary must be ?.
a. floating
b. grounded
c. left ungrounded
d. tertiary connected
The correct answer and explanation is:
The correct answer is b. grounded.
In an open wye-delta connection, the neutral on the primary side must be grounded. This grounding is essential to ensure the proper operation of the system and to provide a clear path for fault currents. Let me explain why grounding is necessary.
The primary side of a wye-delta connection typically involves a three-phase system where the primary side is a wye (Y) configuration, and the secondary side is a delta (Δ) configuration. In a wye connection, there is a neutral point where all three phases meet. This neutral point can be either grounded or left ungrounded.
When the neutral of the primary side is grounded, it helps stabilize the system by providing a reference point for all three phases. Grounding also provides a safety mechanism in case of faults, such as a short circuit to the ground. By grounding the neutral, any potential fault current can flow safely to the ground, reducing the risk of electrical shock or damage to the system.
Without grounding, there could be a floating neutral, which could lead to unbalanced voltages and unpredictable behavior in the system. A floating neutral might result in dangerous situations like overvoltages or under-voltages, causing equipment to malfunction or even leading to damage.
In the case of the delta connection on the secondary side, the neutral is not available, as there is no central point like in the wye connection. However, the primary side neutral being grounded ensures that any imbalance in the system can be properly managed, and it provides a return path for the current in the event of a fault.
Overall, grounding the neutral on the primary side is a key safety measure, ensuring that the system operates correctly and safely.