Overhaul

Standard overhaul of generators and motors comprises the following actions.

Intake and registration:

• visual inspection for transport damage
• missing parts
• parts supplied by customer, type plate data

Initial tests at no load:

• visual inspection
• insulation resistance to earth and internal
• phase resistance
• polarisation index measurement (high-voltage only)
• shock pulse surge test (Baker)
• heating
• temperature sensors
• direction of rotation
• currents
• vibration measurements
• recording of data on accompanying cards

Disassembly of the machine and mechanical measurements:

• recording of bearing set-up/type and model
• visual inspection of the winding and the insulation material
• visual inspection of the rotor cage
• visual inspection of the fan
• measurement of bearing shells on the shaft
• measurement of bearing shells in the shields
• measurement of shaft with respect to the clutch
• visual inspection of the key and/or keyway
• visual inspection of the parts
• recording of data on accompanying cards

Cleaning of all parts

Drying of stator and rotor

Electrical measurements and inspections after drying:

• insulation resistance to earth and internally, phase resistance
• visual inspection of the winding and the insulation materials
• visual inspection of the (“pinch”) connections
• shock pulse surge test (Baker)
• polarisation index measurement (high-voltage only)
• inspection of the keys on the coils
• recording of data

Inspection of the voltage regulator and/or power factor controller

Overhaul of the parts

• turning and milling of slip rings / collector (if applicable)
• replacement of slip rings and/or carbon brushes (if applicable)

Renewal of the bearings

Overhaul of the terminal box:

• replacement of gaskets if necessary
• interior painting
• retightening of connections
• cleaning of earth terminals and connections
• replacement of nuts, rings and strips if necessary

Assembly of the machine

• balancing of the rotor part according to ISO 1940/1G Q 2.5, if necessary

Testing at no load and full load (also single-bearing or sleeve bearing):

• visual inspection
• insulation resistance to earth and internal
• phase resistance
• polarisation index measurement (high-voltage only)
• shock pulse surge test (Baker)
• heating
• temperature sensors
• direction of rotation
• voltage
• currents
• vibration measurements
• recording of data

Acceptance test for classifications (Lloyd’s ,Veritas, DNV, etc.)

External spraying in RAL colour

Notification of ‘ready to ship’, including repair and/or test report

In addition to the standard overhaul of motors and generators, extra work may be necessary.

If measurement to the bearing shells prove that the tolerances are exceeded, EMRI can repair these shells in its own machining workshop in accordance with ISO standards. Bearing shells are repaired by spraying on a coat of liquid metal and turning them again to the correct tolerance.