The correct answer is: C. Unequal line voltages across the load.
A floating neutral is a neutral that is not connected to ground. In a three-phase supply, if the neutral is floating, then the line voltages across the load will be unequal. This is because the line voltages are the difference between the phase voltages and the neutral voltage. If the neutral voltage is not constant, then the line voltages will vary.
This can cause problems for equipment that is connected to the three-phase supply. For example, motors that are connected to a three-phase supply with unequal line voltages will not run smoothly. They may also overheat and damage the windings.
To avoid these problems, it is important to ground the neutral in a three-phase supply. This will ensure that the line voltages are equal and that equipment connected to the supply will operate properly.
Here is a brief explanation of each option:
- Option A: High voltage across the load. This is not the correct answer because a floating neutral does not necessarily cause high voltage across the load. The line voltages may be unequal, but they may not be high.
- Option B: Low voltage across the load. This is not the correct answer because a floating neutral does not necessarily cause low voltage across the load. The line voltages may be unequal, but they may not be low.
- Option C: Unequal line voltages across the load. This is the correct answer because a floating neutral can cause unequal line voltages across the load.
- Option D: None of these. This is not the correct answer because one of the options is correct.