What is a primary condition for an alternator to parallel with a system?

For an alternator to parallel with an existing electrical system, it is essential that it be in phase with the system. This means that the voltage waveforms of the alternator and the system must align perfectly in their phase angle. If the two sources are not in phase, when they are connected, it can cause severe circulating currents, which could lead to equipment damage or system instability.

When an alternator operates in parallel with a utility or other sources, maintaining the same frequency and phase is critical to ensure a smooth and stable power supply. If the alternator is out of phase, it will not synchronize with the system, resulting in a phase difference that can create catastrophic electrical conditions.

To successfully connect an alternator to a system, having the same voltage is also important, but being in phase is the more primary condition because without synchronization, voltage matching alone would not prevent problems during operation. This fundamental recognition of phase alignment is a cornerstone of safe and efficient power engineering practices.