Analysis system for a power supply system, comprising: an automation device (310, 320) and an analysis apparatus for analysing a power supply system, in particular for analysing an earth fault of a power supply system, the analysis apparatus comprising: a. a first connection element for establishing an electrical connection of the analysis apparatus to a line element of a power supply system, in particular to a connection point of the power supply system in the region of a voltage supply for the power supply system, b. a second connection element for establishing an electrical connection of the analysis apparatus to an earth potential, c. a current measuring device for measuring a current through the analysis apparatus between the first and second connection elements, the analysis apparatus also comprising an isolating device which is set up and designed in such a manner that - a continuous, in particular low-impedance, electrical connection exists between the first and second connection elements inside the analysis apparatus in a connection state of the isolating device, and - there is an interruption in the continuous electrical connection between the first and second connection elements inside the analysis apparatus or this continuous electrical connection has a very high impedance in an isolation state of the isolating device, characterized in that d. the analysis apparatus comprises a field bus interface (112, 116) for inputting a control command to the analysis apparatus, the field bus interface (112, 116) and the analysis apparatus being designed and set up in such a manner that the isolating device can be changed from the connection state to the isolation state and/or vice versa by means of a control command which arrives in the field bus interface (112, 116) through a field bus, the automation device (310, 320) being connected to the field bus interface (112, 116) of the analysis apparatus via a field bus line, and the automation device (310, 320) also being configured and set up in such a manner that the isolating device is automatically changed from the connection state to the isolation state via the field bus interface (112, 116) if a current measured value determined in the analysis device exceeds a fixed, predefined or predefinable limit value. an automation device (310, 320) and an analysis apparatus for analysing a power supply system, in particular for analysing an earth fault of a power supply system, the analysis apparatus comprising: a. a first connection element for establishing an electrical connection of the analysis apparatus to a line element of a power supply system, in particular to a connection point of the power supply system in the region of a voltage supply for the power supply system, b. a second connection element for establishing an electrical connection of the analysis apparatus to an earth potential, c. a current measuring device for measuring a current through the analysis apparatus between the first and second connection elements, a. a first connection element for establishing an electrical connection of the analysis apparatus to a line element of a power supply system, in particular to a connection point of the power supply system in the region of a voltage supply for the power supply system, b. a second connection element for establishing an electrical connection of the analysis apparatus to an earth potential, c. a current measuring device for measuring a current through the analysis apparatus between the first and second connection elements, the analysis apparatus also comprising an isolating device which is set up and designed in such a manner that - a continuous, in particular low-impedance, electrical connection exists between the first and second connection elements inside the analysis apparatus in a connection state of the isolating device, and - there is an interruption in the continuous electrical connection between the first and second connection elements inside the analysis apparatus or this continuous electrical connection has a very high impedance in an isolation state of the isolating device, - a continuous, in particular low-impedance, electrical connection exists between the first and second connection elements inside the analysis apparatus in a connection state of the isolating device, and - there is an interruption in the continuous electrical connection between the first and second connection elements inside the analysis apparatus or this continuous electrical connection has a very high impedance in an isolation state of the isolating device, characterized in that d. the analysis apparatus comprises a field bus interface (112, 116) for inputting a control command to the analysis apparatus, d. the analysis apparatus comprises a field bus interface (112, 116) for inputting a control command to the analysis apparatus, the field bus interface (112, 116) and the analysis apparatus being designed and set up in such a manner that the isolating device can be changed from the connection state to the isolation state and/or vice versa by means of a control command which arrives in the field bus interface (112, 116) through a field bus, the automation device (310, 320) being connected to the field bus interface (112, 116) of the analysis apparatus via a field bus line, and the automation device (310, 320) also being configured and set up in such a manner that the isolating device is automatically changed from the connection state to the isolation state via the field bus interface (112, 116) if a current measured value determined in the analysis device exceeds a fixed, predefined or predefinable limit value.