The HMV01 supply units generate a DC bus voltage from the supply voltage. They come in rectifier and rectifier/regeneration variants. Rectifier/regeneration variants can also feed regenerative energy back into the supply network, keeping the DC bus voltage at a constant level regardless of supply voltage. Depending on size, the supply units come with integrated components, such as network contactor, braking transistor or brake resistor. Air cooling is the only type of cooling available.