A Case Study on an End-to-End Safety Risk Management Process

Safety Risk Management plays a critical role in design and development of mission critical equipment such as Power Electronic Systems. These systems are used in Data Centers, EV (Electric Vehicle) and EV Charging Infrastructure, Manufacturing Facilities, Hospitals and in many other industrial and commercial applications. Failures of these systems can potentially lead to Safety issues such as a) Human Injury due to Arc Flash, Shock Hazard, Explosion etc., or b) Property Damage, Regulatory non-compliance issues such as Unsuitable Voltage or Surge Protection during their useful life. These issues can have a detrimental effect on health of the organization and communities at large. Analysis of the root causes for majority of these types of issues have been found to be due to lack of design robustness over the useful life because of ineffective Safety Risk Management process. In this paper, we describe an end-to-end streamlined process to manage Safety Risks during design using an example of a Capacitor Bank Sub-system that is part of Variable Frequency Drive (VFD) System (which is a Power Electronic System). This process consists of i) Identification of CTQs (Critical-to-Quality) characteristics from the Voice of Customer (VoC) & QFD (Quality Function Deployment) analysis, ii) Development of a Parameter (P) Diagram working backwards from the CTQs, iii) Development of Design Failure Modes & Effects Analysis (DFMEA) from P-Diagram and identification of top safety risks via RPNs (Risk Priority Numbers) and Severity Ranking, iv) Deep dive and quantification of Safety Critical Risks i.e., End Effects of Severity of 9 (Property Damage, Regulatory non-compliance) & 10 (Human Injury) identified from DFMEA using FTA (Fault Tree Analysis) and vii) Risk Mitigation & Quantification of Improvements. We have illustrated the application of end-to-end product risk management process on a Capacitor Bank Sub-system of the VFD system as an example and demonstrated that potential design risks were assessed, prioritized, and taken to reduce to a negligible level prior to product launch.