Here's my take: I'll start a list. Others can add.
* Lube oil analysis (may or may not be an on-line sample depending on oil reservoir configuratino).
* Current signature analysis - Use in conjunction with vibration analysis (some people find or confirm misalignment, bearing problems, system oscillations). For us we use it primarily on large motors to monitor for rotor problems.
* Large Critical motors should have winding temperatures monitored by plant computer and sleeve sliding bearing temperatures monitored by plant computer.
* Consider thermography is you don't have temperature monitoring - depends on your preference.
* Current - check magnitude and balance.
* Read winding winding RTD's individually. Leave the highest-reading RTD connected to plant computer input. Investigate unusual difference among RTD's.
* Insulation resistance test / polarization index - gross check for insulation condition and dryness. (IEEE43)
* Winding resistance check - gross test for loose connections or shorted turns (normally shorted turns would
* DC Step voltage test - potentially destructive test which is more sensitive to insulation anomalies than simple insulation resistance / P.I. (IEEE 95.)
* Surge test - potentially destructive test which is more sensitive to weak turn insulation than winding resistance test. Requires expertise to perform. (IEEE 522).
* Insulation power factor = tan delta - another check of insulation condition and dryness. More trendable and sensitive than insulation resistance / P.I. NOT potentially destructive. Equipment is relatively expensive but often is purchased/leased to support transformer testing.
* Check space heaters are on and carrying expected current.
We don't use any of the text boxes from PDMA, BJM, etc. These have many additional tests.