The compact device series ISOMETER® isoXX425

The compact device series ISOMETER® isoXX425
(PresseBox) ( Grünberg, )
The new compact device series isoXX425 monitors the insulation resistances of unearthed AC, AC/DC and DC power supplies (IT systems) according to DIN EN 61557-8 (VDE0413-8) and IEC 61557-8. Measurements are carried out under the most severe conditions. Because power is supplied separate to the system, it is possible to monitor de-energised systems.

Using a multi-voltage power supply unit, the devices can be operated with AC 110/230 V or DC 24 V voltages normally present in control cabinets.

Two individually adjustable response values/alarm relays allow early warning long before the installation reaches a critical state. If the insulation resistance exceeds the release value (response value plus hysteresis) the alarm relays return to their initial position. Both the latest measured values and the alarm messages can be indicated on the LC display. Device parameters are assigned via the LC display, the control buttons on the front of the device or the RS-485 interface.

The compact design of the devices provides a flexible and cost-effective option for insulation monitoring. What this means in practice is:
  • Insulation faults are signalled quickly and reliably and the insulation resistance is clearly indicated on the LC display
  • Two integrated alarm relays
  • Push-wire terminals allow safe and quick wiring
  • Password protection against the unauthorised changing of parameters
  • RS-485 interface for data transmission
This compact device series is used in the following applications:
  • Photovoltaic (isoPV425)
  • Electro mobility in DC charging technology (isoEV425)
  • Railway technology (isoRW425)
  • Energy storage (isoES425)
  • In fact the ISOMETERÒ series iso425 works with different measurement methods which are adaptable to the specific application
The ISOMETER® isoPV425 is only functional as a package with the related coupling device AGH420. Because the power supply is separate to the system being monitored, it is possible to monitor systems up to DC 1000 V and AC 690 V. The two response values are individually adjustable in the range of 1…500 kΩ. The system leakage capacitance is adapted automatically up to a value of 500 µF.

The isoPV425 is specially designed for small and medium photovoltaic systems up to 500 kW. The device is used in solar systems with directly connected inverters or with high system leakage capacitances as well as in photovoltaic systems with high but slow voltage variations. The two-module version (36 mm) plus coupling is extremely space-saving. The two devices which are connected using four wires can be mounted in different positions in the control cabinet or in different control cabinets.

The ISOMETER® isoEV425 with the related coupling device AGH420 monitors the DC side of unearthed charging stations for electric vehicles with a voltage of DC 0…1000 V right up to the motor with AC 0…690 V. The two response values are individually adjustable in the range of 1…500 kΩ. The device adapts automatically to the system leakage capacitance up to a value of ≤ 5 µF with a maximum response time of 10 s.

The space-saving isoEV425 version in a two-module enclosure with the related coupling device is used for DC charging stations (mode 4 in accordance with IEC 61851-23:2014) for charging electric vehicles. During the charging process, the charging station oversees electrical safety on both the charging station and the vehicle. The insulation monitoring device in the vehicle is normally deactivated during this time.

The ISOMETER® isoRW425 monitors the insulation resistance of unearthed AC, AC/DC and DC systems (IT system) in railway applications up to AC/DC 400 V. The two response values are individually adjustable in the range 1…990 kΩ. The system leakage capacitance is adapted automatically up to a value of 300 µF.

The isoRW425 is mainly used in the area of rolling stock and complies with the requirements of DIN EN 50155. Because electrical safety is a key aspect for smooth traction in trains and carriages, special requirements must be met regarding climate, mechanics, shock and vibration. In addition, very different voltages in the range from DC 24 V up to 3AC 440 V must be monitored. It is also necessary to measure the impedance in some railway applications.

The isoES425 monitors the insulation resistance of unearthed AC, AC/DC and DC systems (IT systems) for energy storage devices up to AC/DC 400 V. DC components existing in AC/DC systems do not influence the operating characteristics. The isoES425 is used to monitor and indicate the connection to earth during network operation. When operated as an isolated system the isoES425 takes over the monitoring of the isolated system (IT system).
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