Fronius International Gmbh

Bernhard Doppelbauer

Stefan Wieser

Andreas Luger

Bernhard Staudinger

Gerhard Reiter

Roland Jungreithmair

Martin Wolf

To determine an AC insulation resistance between the AC connections of an inverter and a ground potential, the AC connections are connected to an AC energy sink in an emergency standby operation in order to transmit energy from a DC energy source to an AC energy sink and an insulation test is performed in emergency standby operation. An AC fault current flowing between an AC connection and the ground potential is determined, and the AC insulation resistance is calculated from the AC fault current.

Monitoring device for emergency standby operation

The invention relates to an inverter () for converting a direct voltage (U) into an alternating voltage (U) for feeding into a single-phase three-conductor network () and for supplying loads (), comprising a DC input (), an intermediate circuit () having an intermediate circuit center point (), a DC/AC converter () having at least two half bridges (), a control device (), and an AC output () for connecting to the single-phase three-conductor network () and the loads ('). The invention further relates to a method for operating such an inverter (). According to the invention, the control device () is designed to connect, in an emergency power operation (BOM), one half bridge () of the DC/AC converter () to a phase conductor (L) of the AC output (), to connect the other half bridge () of the DC/AC converter () to another phase conductor (L) of the AC output (), and to connect the intermediate circuit center point () to the neutral conductor (N) of the AC output () and to halve the amplitude of the output signal (U, U) of the half bridges (), and to perform a phase shift of the output signal (Uor U) of one half bridge (or) by 180&#xb0; such that at least some loads () can also be supplied in emergency power operation (BOM).

Inverter and method for operating an inverter

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Krenglbach, Austria

Bernhard Doppelbauer