...lus) K8AK-VW(Screw terminal) Single-phase Upper and Lower Voltage Unnecessity Voltage detection SDV-F Upper or Lower Voltage Unnecessity SDV-D Upper and Lower Voltage Unnecessity ...https://www.ia.omron.com/data_pdf/cat/measuring_and_monitoring_relays_application_guide_n222-e1_1_1_csm1129790.pdf