Method and device for insulation monitoring of non-grounded electrical DC and AC grids

US8994379B2 · kind B2 · utility

Assignee

• ABB AG · US

Inventors

• Frank Brenk · Hausach, DE
• Franz-Otto Witte · Landsberg am Lech, DE
• Wolfram STREPP · Glückstadt, DE

Key dates

• Filing date: Nov 15, 2011
• Grant date: Mar 31, 2015
• Expiry date: Jul 7, 2033

Classification

• Technology area (CPC G): Physics
• CPC primary: G01R31/52
• WIPO field: Measurement
• WIPO sector: Instruments

Abstract

Exemplary methods are directed to insulation monitoring of non-grounded electrical DC power supply systems and AC power supply systems which have a resistive (Rf) and capacitive (Cf) insulation impedance between the power supply system and ground. The method includes applying a pulsed AC voltage (U0) having alternately different pulsed voltage values to the power supply system to be monitored via a resistive system interface (Ri) between the power supply system and ground. The insulation impedance (Rf) between the power supply system and ground is determined using time profiles of transient processes of the measurement voltage (Vm) prior to transient recovery of the power supply system to the respective pulsed voltage value (U0) of two polarity-inverted pulsed voltage value application processes.