Permitted voltage systems

TN and TT systems – voltage systems with directly grounded star point

Use is possible without restrictions.

IT systems – voltage systems with non-grounded star point

Use is only permitted with adherence to the following measures:

• The device must be connected to the protective earth. Observe the Notes on PE connection.
• If an insulation monitoring device is used, it must be capable of measuring the insulation resistance of the grid even if ground capacitances are present in the system.
• In the event of a line-side ground fault, the DC link voltage may increase. This can be prevented by using an external braking resistor; in this case, the smallest permissible braking resistor is sufficient.
• The EMC limit values for interference emission are not specified for voltage supply systems without grounded star point (IT systems). The effectiveness of line filters is severely limited.

The EMC contact screws can be used to deactivate the filter capacitors used in the device, which reduces the ground capacitance. This affects the interference suppression of the device and may impair electromagnetic compatibility (EMC).

When removing the EMC contact screws, proceed as follows:

1. Remove all existing EMC contact screws from all devices only when used in IT systems. The positions of the EMC contact screws can be found in the product manual > chapter Device structure.
2. Mark this on the nameplate in the "IT system activated" box provided for this purpose.

Voltage systems
with grounded outer conductor

Use only for nominal line voltages up to max. 240 V.