Hi Peeps! Been out of the country for a while so I’ve not monitored the site for a while. Now I’m back at work and have a problem on my first day!!

It’s easiest to explain if you look at the attachment. This is a plot of system availability over time, where Preventive Maintenance (PM) is carried out at set intervals. It should be a sort of square wave with sloping or curved tops, the curvature of the top being varied by the value of “Beta”.

The value (t-x) is used to reset the elapsed time to zero whenever PM is done. The formula is =MOD(Time, PM Interval).

The column “Plotted Availability” is used to create ‘dropouts’ in the chart for the duration of the PM, which is set by the value of ‘MTTR’

In the “Parameters” block, Yellow cells are user-entered values, Blue cells are calculated values.

The plot doesn’t quite do it for me, because it zigs down to zero at the PM point, then zags back up, MTTR hours later. What I need is for it to drop instantly to zero at the PM Point, stay at zero for MTTR hours, then rise instantly to the value of A at PM+MTTR hours. I realise this will require 4 plotting points for each PM instead of the current 3, but I’m at a loss as to how to implement this – any clues much appreciated.