In a large-scale 100MW photovoltaic (PV) system with a Ni-Cd battery energy storage system (BESS) operating at medium voltage, detecting earth faults early is crucial for maintaining reliability, safety, and efficiency. An unearthed DC system, while reducing ground fault currents, requires specialized monitoring to prevent insulation degradation and system failures.
To achieve early warning detection, the most effective approach involves insulation monitoring devices (IMD), residual current monitoring (RCM), and voltage asymmetry detection. These methods ensure that even the slightest insulation faults are detected before they escalate into critical failures.
For the PV system, the Bender ISOMETER® isoPV1685P is an ideal choice. Designed for PV arrays up to 1500V DC, it continuously monitors insulation resistance and provides real-time alerts. In cases where the voltage exceeds this range, the Hakel HIG95-PV, capable of monitoring systems up to 3kV DC, ensures comprehensive protection.
On the battery storage side, where the Ni-Cd system operates at medium voltage, the Bender ISOMETER® IRDH275 is well-suited for continuous insulation monitoring. This device not only detects insulation faults early but also integrates seamlessly into large-scale BESS infrastructures. Additionally, the Megger BITE3 battery impedance tester helps assess long-term insulation degradation, ensuring the health of the battery system.
For a centralized monitoring solution, the Bender LINETRAXX® RCMS490-D is recommended. This system provides a holistic approach to monitoring multiple DC circuits, offering residual current detection and insulation monitoring across the PV and BESS infrastructure.
All recommended devices comply with IEC 61557-8, IEC 62109-2, IEC 62619, and UL 9540, ensuring adherence to international safety and performance standards. By implementing these advanced detection systems, the 100MW PV and Ni-Cd BESS can operate with enhanced safety, minimized downtime, and maximized efficiency.