What is the maximum allowable voltage imbalance between any leg of a 3-phase power supply?

The maximum allowable voltage imbalance between any leg of a 3-phase power supply is typically considered to be 2%. Maintaining this level of voltage imbalance is crucial for the efficient and safe operation of three-phase equipment. An imbalance above this threshold can lead to overheating and reduced efficiency in motors, transformers, and other electrical devices, which may shorten their lifespan or lead to failure.

In a three-phase system, the phases should ideally have equal voltages for optimal performance. When the voltage across any of the phases deviates significantly from the others, it can result in unbalanced loads, which can generate excessive current in certain phases while others may not be fully utilized. This imbalance can also cause increased losses, impacting energy efficiency and potentially leading to operational issues.

Understanding the 2% standard helps professionals ensure that electrical equipment operates within safe parameters and minimizes potential damage or operational inefficiencies.