Testing of Inter-Laminar Insulation of Stator Cores Using ELCID

The reliability of large generators is of major importance to maintain the integrity of power plant. Continuous monitoring or frequent inspection is therefore desirable to be able to remedy growing defects before a catastrophic failure or more major work becomes necessary. Recent test information may also permit more effective use of routine or unscheduled outages by means of additional preparation and provisioning. The stator core is a major electro-mechanical component of a generator to which this applies in particular, as failure and associated repair or replacement necessitates major disassembly of other parts of the machine. Information on condition of the core structure is therefore significant, but is increasingly difficult to obtain at frequent intervals. Low power core testing can be performed more quickly and easily than using traditional full flux methods and may need to be considered an indispensable tool to increase or maintain essential monitoring levels. Low power core testing presents opportunities to maintain the level of stator core lamination monitoring in a more time and resource efficient manner using comparatively short windows in available outage time, often partly overlapping with other concurrent maintenance activities. These opportunities are enhanced with wider use of low power EL CID testing without removal of the rotor, not feasible with thermal loop tests.