Method and device for shutting down an installation part exhibiting an insulation fault in an ungrounded power supply system

Patent metadata

Field	Value
Publication number	US-2016336732-A1
Application number	US-201615149777-A
Country	US
Kind code	A1
Filing date	May 9, 2016
Priority date	May 11, 2015
Publication date	Nov 17, 2016
Grant date	—

Abstract

The invention relates to a method and to a device for shutting down an installation part provided with connected equipment in an ungrounded power supply system in case of an insulation fault in a direct-current circuit connected to the installation part to be shut down. The invention is based on first determining the insulation resistance of the IT power supply system and measuring the displacement direct voltage present in the IT power supply system and then determining by combined evaluation of the measured results if there is a risk of an disruptive influence on the operating behavior of the connected equipment due to the displacement direct voltage occurring during the duration of a predeterminable time interval. If a disruptive influence is to be expected, the installation part exhibiting the insulation fault is immediately shut down together with the direct-current circuit and the equipment connected thereto.

First claim

1 . A method for shutting down an installation part ( 6 ) provided with connected equipment in an ungrounded power supply system ( 2 ) in case of an insulation fault in a direct-current circuit ( 8 ) connected to the installation part ( 6 ) to be shut down, comprising the method steps of:
determining an insulation resistance (Riso) of the ungrounded power supply system ( 2 ), determining, for all outer conductors of the ungrounded power supply system ( 2 ), a displacement direct voltage (Uv) between the respective outer conductor and ground, shutting down the installation part ( 6 ) exhibiting the insulation fault if the obtained insulation-resistance value (Riso) is smaller than a predeterminable insulation-resistance limit value (Ran) and the obtained displacement direct voltage (Uv) is greater than a predeterminable direct-voltage limit value (Uan) during the duration of a predeterminable time interval (Tan).

2 . The method according to claim 1 ,
characterized in that the predeterminable direct-voltage limit value (Uan) with the associated predeterminable time interval (Tan) is determined as an OR-connection of a first direct-voltage limit value with an associated first time interval and a second direct-voltage limit value with an associated second time interval, the first direct-voltage limit value being higher than the second direct-voltage limit value and the first time interval being shorter than the second time interval.

3 . The method according to claim 1 ,
characterized in that the predeterminable insulation-resistance limit value (Ran), the predeterminable first/second direct-voltage limit value and the predeterminable first/second time interval are set according to the electrical parameters of the connected equipment.

4 . The method according to claim 1 ,
characterized in that digital filter algorithms and synchronization algorithms are used to determine the insulation resistance (Riso) and the displacement direct voltage (Uv).

5 . The method according to claim 1 ,
characterized in that at least a partial insulation resistance of a switched-off installation part ( 6 ) having a direct-current circuit ( 8 ) is determined and the switched-off installation part ( 6 ) is blocked from being connected if the partial insulation resistance falls short of a partial insulation-resistance limit value.

6 . A device for shutting down an installation part ( 6 ) provided with connected equipment in an ungrounded power supply system ( 2 ) in case of an insulation fault in a direct-current circuit ( 8 ) connected to the installation part ( 6 ) to be shut down, comprising an insulation monitoring device ( 20 ) for determining an insulation resistance (Riso) of the ungrounded power supply system ( 2 ),
characterized in that the insulation monitoring device ( 20 ) comprises a voltage measuring device ( 26 ) for determining a displacement direct voltage (Uv) between a respective outer conductor of the ungrounded power supply system ( 2 ) and ground and an evaluating device ( 28 ) for combined evaluation of the insulation-resistance value (Riso) and the displacement direct voltage (Uv).

7 . The device according to claim 6 ,
characterized by a switching device ( 22 ) for shutting down the installation part ( 6 ) exhibiting the insulation fault.

8 . The device according to claim 6 ,
characterized by a separate offline insulation monitoring device ( 30 , 32 ) for determining a partial insulation resistance of a switched-off installation part.

9 . The device according to claim 8 ,
characterized in that the insulation monitoring device ( 20 ) comprises a locking circuit ( 29 ) connected to the offline insulation monitoring device ( 30 , 32 ) via a communication device ( 34 ).

Assignees

• Bender Gmbh & Co Kg

Inventors

• Hackl Dieter
• Schaefer Oliver

Classifications

• H02H7/268 Primary

  for DC systems · CPC title

• H02H7/26

  Sectionalised protection of cable or line systems, e.g. for disconnecting a section on which a short-circuit, earth fault, or arc discharge has occured (locating faults in cables G01R31/08) · CPC title

• G01R27/025

  Measuring very high resistances, e.g. isolation resistances, i.e. megohm-meters · CPC title

• H02H3/165 Primary

  for three-phase systems · CPC title

• G01R31/12

  Testing dielectric strength or breakdown voltage {; Testing or monitoring effectiveness or level of insulation, e.g. of a cable or of an apparatus, for example using partial discharge measurements; Electrostatic testing (G01R31/08, G01R31/327 and G01R31/72 take precedence; measuring in plasmas G01R19/0061; measuring dielectric constants G01R27/2617; ESD, EMC or EMP testing of circuits G01R31/002)} · CPC title