Reco Transformers Pvt. Ltd. Offers Summation Current Transformer with Primary Windings. Reco Transformers Pvt. Ltd. Is an ISO 9001:2000 awarded company. The company manufactures Low Tension Current Transformers and Potential and Control Transformers. The Summation Current Transformer with Primary Windings consist of two or more primary windings which are connected to the feeders to be summed , and a single secondary winding, which feeds a current proportional to the summed primary current. The Summation Current Transformer with Primary Windings are used when the currents in a number of feeders need not be individually metered but summed to a single meter or instrument.