Patent ID: 8310242

Claim:
A method for insulation monitoring in an inverter application, in a test phase of the inverter application wherein the inverter application comprises an intermediate voltage circuit with at least one positive branch and a negative branch; at least one electrical apparatus which comprises at least two phase connections; at least one inverter with switch elements for the electrical connection of the phase connections to the positive branch or the negative branch of the intermediate voltage circuit; and wherein the method comprises the following steps: in a first test configuration, simultaneously switching-on of one or more switches for connecting only a first branch of the inverter to one or more phase connections, wherein the second, opposite branch is not connected to the phase connections; measuring at least one of a voltage of the positive branch and a voltage of a negative branch; determining values of characterizing variables of a function of at least one of these measured voltages; determining insulation defects at the intermediate voltage circuit and/or at the phase connections and/or at the electrical apparatus by comparing these characterizing variables with corresponding reference values, and, if a deviation from the reference values exceeds a predetermined limit, signaling the presence of an insulation defect.