Electric utilities require secure network and control system communications that conform to the recommendations of the NERC (North America Electric Reliability Corporation) CIP (Critical Infrastructure Protection) cyber security framework for identification and protection of critical cyber assets to support reliable operation of the bulk electric system. Major technological requirements of secure control networks are summarized in this paper. Implications of the newly developed IEC 62351 security standard for SCADA data and communication protocols are included. The paper reaches beyond the current standards and recommendations, in that it introduces a new reference secure control network architecture that is a sound foundation for conformance to the regulatory security requirements and industry standards related to control network operation, like NERC CIP, IEC and NIST.