Which is the first step when paralleling two transformers?

When paralleling two transformers, the first step is to ensure that the grounds and neutrals are properly connected. This step is crucial because it establishes a common reference point for both transformers, which is necessary for their safe and efficient operation. If the grounds and neutrals are not connected appropriately, it can lead to circulating currents, equipment damage, or safety hazards.

Establishing a proper ground and neutral connection helps to equalize potential and minimizes the risks of phase imbalances when the transformers are energized. It is essential to make sure that these connections are secure and conform to code requirements before proceeding to energize the transformers or make any other electrical connections. Ensuring a solid electrical ground also enhances the reliability and safety of the system.

In contrast, connecting the primary side of both transformers before ensuring proper grounding can lead to complications if one transformer experiences a fault. Energizing one transformer before establishing a common ground can also create dangerous conditions. Disconnecting the secondary side is not a necessary first step when preparing to parallel transformers; rather, it is more pertinent in situations where maintenance or testing is required.