The operation, control and protection of EHV substations have benefited immensely from advancements in electronics, computers, information and communications technology. The use of IEC61850 compliant digital protection relays, digital energy meters, smart monitoring devices and other smart interactive IEDs are being extensively used in all EHV substations. The integration and convergence of developments in computer, communication, electronics technologies with power system control and protection have revolutionized the way substations are now being operated. Nowadays, 400 KV and above voltage class new EHV substations of Indian central and state utilities are invariably being designed with IEC61850 based SAS. However, new 132 KV class substations are still constructed without Substation Automation System owing to substantial cost implication SAS. Further, for the same reason a majority of old EHV substations in Indian power utilities could not be provided with SAS so far. This paper presents a case study on low-cost implementation of IEC 61850 based substation automation in old and smaller conventional hard wired 132 KV substations and thus converting them into smart substations. The paper begins with a brief description of a typical 132 KV class substation, followed by an introduction to Substation Automation system and IEC 61850 based SAS. Thereafter, the paper discusses design aspects of implementation of economically optimized SAS in conventional hard-wired Substations and discusses benefits of implementation of SAS in 132 KV class Substations. The paper concludes with a discussion of the benefits of adoption of IEC 61850 based substation automation system in conventional EHV substations.