Addendum to IB 18.4.7-2E - Types 27D and 27H - Single-phase Undervoltage Relays for 25Hz
Types 27, 27D, 27H, 59, 59D, 59H - Circuit Shield - Undervoltage and Overvoltage Relays
Single-Phase Voltage Relays - UNDERVOLTAGE RELAYS and OVERVOLTAGE RELAYS
Types 27D and 27H - Single-phase Undervoltage Relays for 25Hz