© 2021 Praise Worthy Prize S.r.l.-All rights reserved.In recent years, the structure of the electricity grids has changed remarkably because of developing technology and smart grids have started to be used instead of classical ones. IEC 61850 standard is widely used in communication of smart grids. Smart grids bring additional risks along with the many benefits they provide. One of these risks is the vulnerabilities in communication systems; they are vulnerable to cyber-attacks, weakening the security. There are numerous studies in the literature about the detection and the prevention of the vulnerabilities caused by the communication network. However, there are no detailed studies on the investigation and the detection of cyber-attacks that can be made through physical access to smart grids spread over a wide area. Furthermore, difficulties in validation of intrusion detection system (IDS) and a number of problems in IDSs cause vulnerabilities, which make smart grids vulnerable to cyber-attacks. In this study, physical access cyber-attacks are examined and an intrusion test is done within Istanbul Technical University (ITU) Electrical Distribution Automation Laboratory, which is a modern testbed and communicates with IEC 61850 standard, Supervisory Control and Data Acquisition (SCADA) system. In order to determine the physical access cyber-attacks on time and to take necessary precautions, open source software is used. It is shown that physical access cyber-attacks to smart grids can be prevented with the established testbed.