Error “Move-SPSite : Execution Timeout Expired.”

I want to move a 30GB Site Collection to another content database. This should be done with PowerShell with the Move-SPSite command. After about 40 Minutes the job stops with the following error Message:

Move-SPSite : Execution Timeout Expired. The timeout period elapsed prior to completion of the operation or the server is not responding. At line:27 char:1 + Move-SPSite -Identity $ SiteUrl -DestinationDatabase $ DestinationDB -Confirm:$ fal … + ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ + CategoryInfo : InvalidData: (Microsoft.Share…PCmdletMoveSite:SPCmdletMoveSite) [Move-SPSite], SPCmdletException + FullyQualifiedErrorId : Microsoft.SharePoint.PowerShell.SPCmdletMoveSite

We’ve increased the execution timeout but this helped nothing. We tried the command also with other site collections and everything worked fine. Any ideas what we can do?