Large Power Plant Generators : Mfg, Erection, Testing & QC

A: Uniform rust would bias inspection toward laminations and miss the electrical aging that actually trips you later. Galvanic attack sounds intuitive but lacks a sustained electrolyte inside a properly sealed machine. Chloride pitting is real offshore yet doesn't align with the observed insulation dulling and PD risk. Moisture lowers insulation resistance and accelerates PD, so insulation chemistry and dryness dominate the material call.

A: Cranking voltage skews results and adds heating that confuses diagnosis. Blind acceptance ignores the adverse trend that often precedes failure. Uncontrolled drying can give a false sense of recovery without fixing ingress. Temperature-corrected trending tells you whether the insulation system is stabilizing.

A: Vibration isn't the primary symptom of gas density change in a tight machine. Field tweaks misaddress a thermal problem and can elevate rotor heating. Lower losses is backwards because denser gas increases windage. Purity recovery restores cooling and limits windage heating while seal oil keeps air out.

A: Calling it negligible hides a heat source that stacks on already tight margins. Ignoring density misses why hydrogen is used in the first place. Viscosity-led scaling overstates losses and misguides actions. Density and speed dominate, so small purity shifts matter at high rpm.