By "static" I mean the equipment would have to be picked up and carried somewhere else, and there would be no pantograph present so it would measure the rest position of the OLE. You get different results if there is a pantograph present because that will lift the wire, and probably different again if the pantograph and the measuring equipment are moving.
An excellent series of points.
Just to add, for himarele
The majority of Network Rail's in-house measurements today are taken with pantograph down using the New Measurement Train, whilst the equipment on service trains (such as the new ThamesLink Class 700 trains) will be recording with the pantograph up.
That allows, if it's needed or wanted, a comparison between the OLE when it's used with and without a pantograph applying uplift force.
Static testing and low speed testing is generally restricted to installation testing, either new electrification, re-wiring, re-modelling of track and associated OLE or repairs after a dewirement. There may be some limited static testing if there's issues with pantograph carbons being chipped/damaged, and there's also bit of work ongoing with Furrer+Frey, Network Rail and various contractors to use drones for this sort of thing.
The combined approach - more data recording, new ways of recording data and the recording of additional parameters is solely to improve the reliability of the OLE systems used, we want to catch issues before they result in dewirements.
We can usually find the root cause of a dewirement, but much of the research work now is to find out what, if anything, we can see or detect before a dewirement, such a thermal signature from a damaged insulator, different/unusual oscillations which show a tensioner or pully has become sticky, before it seizes completely, or even bird feathers on the catenary to indicate a bird strike.