When does the need for an overhaul inspection arise? Routine inspection results, along with the generator operating hours, may demonstrate a need for an overhaul inspection. If the routine inspection results are good, then the need for an overhaul can be determined on the basis of the equivalent hours.
teq = top + 10Ns (h)
teq = equivalent operating time
top = effective operating time
Ns = number of starts
Experience has shown that the first overhaul is performed after approx. 20 000 equivalent hours, and following after approx. 80 000 equivalent hours.
Determining the status of components is partly based on a visual control, control of the dimensions, control of the verticality and cable armor, electrical and mechanical tests.
The basic overhaul operations are determining the:
- Stator housing status
- Stator packet status
- Stator winding status
- Rotor poles status
- Shaft and pole wheel status
- Supports status
- Bearings status
- Status of the ventilator and the braking ring
- Status of brakes
- Cooling device status
- Slip ring status
- Electrical and mechanical tests
Based on these data and the routine inspections data, the generator status can be evaluated and necessary interventions can be determined.
The overhaul implies the generator dismantling with decoupling of the rotor and its pulling out.