Hi @Anonymous ,
We can just add two steps to get the duration time if your excel is format as hh:mm:ss:
[Duration] - #datetime(1899,12,31,0,0,0)


Then just delete the origin column and rename the new column

The full version M Query is here:
let
Source = Excel.Workbook(File.Contents("D:\Test\2019-10-08\Duration-time.xlsx"), null, true),
Sheet1_Sheet = Source{[Item="Sheet1",Kind="Sheet"]}[Data],
#"Promoted Headers" = Table.PromoteHeaders(Sheet1_Sheet, [PromoteAllScalars=true]),
#"Added Custom" = Table.AddColumn(#"Promoted Headers", "Custom", each [Duration] - #datetime(1899,12,31,0,0,0)),
#"Changed Type" = Table.TransformColumnTypes(#"Added Custom",{{"Custom", type duration}}),
#"Removed Columns" = Table.RemoveColumns(#"Changed Type",{"Duration"}),
#"Renamed Columns" = Table.RenameColumns(#"Removed Columns",{{"Custom", "Duration"}})
in
#"Renamed Columns"you can use time to show in the field, or keep the origin duration number (the total day)

BTW, pbix and excel as attached.
Best regards,
Community Support Team _ Dong Li
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.
Community Support Team _ Dong Li
If this post helps, then please consider Accept it as the solution to help the other members find it more quickly.