Production Downtime Minutes is the sum of downtime minutes excluding planned non-production minutes. For example, if a 60 minute pitch has 20 minutes planned non-production, and 40 minutes planned production, and a "down" dispatch is open for the entire duration of the pitch, only 40 minutes are counted toward production downtime.
Production Downtime Minutes are used when calculating OA on the Operator Portal, Dashboards, and Pitchboards. (OA % = Operational Availability)
You can find the Production Downtime Minutes on the Daily and Weekly Summary Reports.
Example: 
You can see the first pitch has 30 planned production minutes and 30 non production minutes, along with a downtime event that lasted 60 minutes (exceeding the planned production time). Instead of using the 60 minutes of downtime to calculate the OA, we use the Production Downtime Minutes of 30. (90 - 30)/ 90*100 = 66.67