With the advent of modern technologies, microprocessor-based devices are used to monitor and control critical infrastructures, e.g., electric power grids, oil and gas distribution. However, the security and reliability of these microprocessor-based systems is a significant issue, since they are more susceptible to transient errors and malicious attacks. An error in one of these systems could have a cascading and catastrophic impact on the whole infrastructure. This paper explores the error resiliency of power grid substation devices. A software-implemented fault injection technique is used to induce errors/faults inside devices used in power grid substations. The goal is to test the ability of these systems to compute through errors/faults. Our results demonstrate that a single error in a substation device may render the operator in the control center unable to control the operation of a relay in the substation.