You're right to be confused. Feeding a 208/120V panel into a transformer to get 208/120V out seems redundant at first glance. However, there are a few potential reasons why this setup might exist, especially around sensitive equipment like MRI and CT scanners in a veterinary clinic

Possible Reasons for a 208/120V to 208/120V Transformer:
Isolation Transformer for Noise Reduction

This is the most likely explanation. Isolation transformers are specifically designed to isolate the load (the convenience outlets and anything plugged into them) from the source (the 208/120V panel).

Common Mode Noise

MRI and CT equipment are highly susceptible to electrical noise, especially common-mode noise. This noise can originate from the building's electrical system (motors, lighting, other equipment) and travel through the ground. An isolation transformer significantly reduces this common-mode noise by breaking the direct ground connection.

Ground Loops

Isolation transformers eliminate ground loops, which can also introduce noise and even potentially create a safety hazard.

Clean Power

Even though the voltage is the same, the transformer can act as a filter, smoothing out voltage fluctuations, transients, and harmonics present in the main electrical supply. This "clean power" can be crucial for sensitive electronic equipment.

Dedicated Grounding System

The isolation transformer may be part of a dedicated grounding system for the MRI/CT area. This can help to minimize ground currents and ensure a stable ground reference for the equipment.

Voltage Stabilization

While less common with modern electrical systems, a transformer could be used to provide a more stable voltage. Voltage fluctuations can negatively impact the performance of sensitive electronics.

Safety

Some isolation transformers are designed with enhanced safety features, providing additional protection against electrical shock. This can be especially important in a veterinary clinic where there might be wet environments or vulnerable patients.

Future Planning

Maybe, in the future, there are plans to install a 120v dedicated circuit, and having a transformer would allow this option.

Important Considerations



K-Rated Transformer

If the intention is to mitigate harmonics, the transformer should be a K-rated transformer. Standard transformers are not designed to handle harmonic currents, which can cause overheating and premature failure.

Transformer Size

The transformer must be properly sized to handle the load connected to the convenience outlets.*

Local Codes and Regulations

Check local electrical codes and regulations, as they may have specific requirements for electrical installations in medical facilities or around sensitive equipment.

In Summary:

The most probable reason for using a 208/120V to 208/120V transformer in this application is to provide electrical isolation, reduce noise, and create a "clean" power source for the convenience outlets around the MRI/CT area. This helps protect the sensitive equipment and ensure accurate diagnostic imaging. Flag for review