Application challenge
- Transformerless PV inverters improve efficiency but require careful ground-insulation diagnostics.
- The test network should not become a permanent leakage path from the PV string to earth.
- High humidity, pollution and outdoor thermal cycling can reduce effective insulation.
Design approach
- Place the relay in the measurement path so the insulation test can be performed before the inverter energizes the main power stage.
- Design PCB spacing and conformal coating around the relay according to PV string voltage and environmental class.
- Validate insulation readings across temperature, humidity and aging because leakage can come from the board as well as the relay.
- Keep the measurement algorithm tolerant of contact timing and residual capacitance.
Engineering caution: catalog ratings are component-level references. For high-voltage, medical, EV, PV or ATE systems, verify creepage, clearance, leakage, thermal rise, EMC and lifetime in the finished equipment.
Related MiRelay series
High-voltage high-insulation reed relays are used where the PV diagnostic path must remain isolated from ground outside the test window.
Series mentioned: High-voltage high-insulation reed relays