The A-ISOMETER® of the IR470LY2 series is designed to monitor the insulation resistance of unearthed AC and three-phase systems (IT systems) AC / 3(N)AC 0…793 V. The device series is particularly suitable for systems requiring a high insulation level. The device can also be used for monitoring de-energized loads. Two separately adjustable response values / alarm relays allow a distinction to be made between "prewarning" and "alarm". In combination with a coupling device the device series can be used for higher voltages.

The systems to be monitored should not contain DC components. Due to the measuring principle, insulation faults behind directly connected rectifiers are indicated with increased response sensitivity. The set response values apply to the pure AC system only.

• Insulation monitoring for unearthed
  AC / 3(N)AC systems 0…793 V
• Off-Line monitoring for TN, TT and IT systems
  0…793 V
• Nominal voltage extendable via coupling device
• Operating mode selectable: Insulation monitoring / offline monitoring
• Two separately adjustable response values
  100 kΩ…1 MΩ / 500 kΩ…5 MΩ
• Connection monitoring system / earth

• AC / 3(N)AC main circuits (without directly connected rectifiers), such as motors, pumps, rolling mills without variable-speed drives, air cooling and air cinditioning systems, light­ing systems, heating systems, mobile generators, building services, domestic electrical installation practice, etc.
• De-energized loads, such as fire extinguisher pumps, slide-valve drives (gas, water, oil etc.), flue gas valves, cranes