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Control Transformer Bank

This bank of transformers is being used to power several VAV box controllers. The VAV box in the previous picture is powered by one of these transformers. In most VAV box applications, the power for the control system is at the box and an properly sized transformer for VA load is used to power the controller. In this application, the VAV boxes were not fan powered and line voltage was not available at the boxes. So a central transformer bank was used and wire for control power was pulled to each VAV box.

Using the manufactuers rating of the DDC controller and the power needed to drive all the actuators which is also a VAV rating on the actuators, the entire load was calculated and the appropiately sized transformers were used. If the load demand for the transformer exceeds the transformers VA rating the controllers may not work properly and the transformer will over heat and eventually fail. With the number of transformers in this panel a fan was necessary to remove the heat from inside the panel. Transformers generate a lot of heat and it is important to have a method to keep them cooler.

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