A transformer system includes a transformer and a transformer tank. The transformer tank houses the transformer in a bath of a dielectric fluid. The transformer system also includes a controller, and a fiber optic sensor communicatively coupled to the controller. The fiber optic sensor is disposed in the dielectric fluid and operative to provide an output that varies with the level of the dielectric fluid. The controller is operative to determine the level of the dielectric fluid based on the output of the fiber optic sensor.