Patent ID: 8174268

Claim:
A method of monitoring a protective relay system comprising: sensing a first signal current flowing from a protective relay; storing said first signal current; identifying a first signature portion of said first signal current; comparing said first signature portion against a reference signature; and, identifying an undesired operating condition from said first signature portion; wherein said reference signature is a database including a plurality of reference signatures, wherein each of said plurality of reference signatures is associated with a different undesired operating condition; wherein sensing a second signal current flowing from said protective relay; storing said second signal current; identifying a second signature portion of said second signal current; comparing said second signature portion against said first signature portion comparing said second signature portion against said database of reference signatures; and, determining a change in a behavior pattern of said first signature portion and said second signature portion; comparing said change in behavior pattern to said database of reference signatures, and initiating corrective action when said change in behavior pattern indicates an undesired operating condition.