Motor Current Signature Analysis (MSA) is one of the testing tools used to assess motor health, reliability and predictive maintenance. This tool allows professionals to establish a baseline and trend for P-F curve intervention to reduce motor failure and production downtime. The ideal tester should have the ability to do dynamic and static testing that is mean dynamic on line testing power quality, inrush current, current, voltage imbalance etc., This will also allow for testing polarization index resistive and inductive imbalances, quality control checks after receiving motors from repair. Other test than can be done through MSA include eccentricity air gap, rotor influence, etc. The important thing to remember is to identify your critical motors and size of motors on all nameplate data and to see if it is reasonable and economical to implement this tactic, as the MSA can be expensive and their needs to be an return on investment (RO) justification.
Motors like the 900 HP, 1100 HP, 1500 HP, 3500 HP, and 14000 HP are worthy of collecting data under this program for CBM. I've found that even in small motors such as the 350 HP, which are critical for production, are also worthy to monitor to ensure the capacity of plant. If you cannot have this testing done in house, then you can contract these services to electrical companies.
The MSA is a great tool for testing and troubleshooting various fault zones, including power quality, power circuit, harmonics, stator, rotor, air gap and insulation. In general the motor faces four stresses: 1.Thermal, 2. Electrical, 3. Mechanical, 4. Environmental. With MSA, you will be able to check each one.