Substation security as part of critical electricity infrastructure plays a crucial role in preventing material and social losses due to interference or unauthorized access. Unfortunately, the security system that has been used so far is still conventional such as manual locks, which in fact are vulnerable to misuse or break-in. Based on this, this research is designed to create a substation door security system with dual biometric authentication technology, namely by combining Fingerprint sensors (AS608) and face sensors (ESP32-CAM) connected via the Internet of Things (IoT) and controlled using Arduino Uno. The research method was carried out through literature review, device
design, program development, and direct testing of prototypes at the Duri Kosambi Substation. From the test results, this system proved to be able to recognize the user's identity with good accuracy under normal conditions, although the performance decreased when the fingers were dirty, the face was covered with accessories, or the lighting was less supportive. The security system also proved to be more practical and faster than ordinary keys, and can be monitored remotely in real-time via an IoT connection. Overall, This system is expected to be able to maintain national vital facilities such as PLN substations.