Generator Service Capabilities

With over 150 years of experience, Siemens-Energy is a world leader in generator technology and has manufactured many of the largest and most efficient generators in the world.


With Siemens-Energy as your service partner, you can have the full benefits of the expertise of our turbine-generator factory personnel, design engineering, service engineering groups, and our regional management and service expertise. We are knowledgeable of potential turbine-generator issues through significant fleet experience and have developed an enormous backlog of field processes, procedures, tooling and trained personnel to quickly address them.

Our Generator Service Capabilities in Detail

  • AC Maintenance and Overpotential Tests
  • DC Maintenance and Overpotential Tests
  • Dielectric Absorption
  • Leakage Voltage
  • Insulation Resistance of Each Phase 
  • RTD and T/C Insulation Resistance
  • Through Bolt Insulation Resistance
  • Thermocouple Continuity
  • Tube-to-Tube Resistance  (If present)
  • Tube-to-Copper Resistance  (If present)
  • RTD Internal Resistance Measurements
  • Phase Resistance Measurements 
  • Transposition Test   (If applicable)
  • Stator Core SMCAS Test
  • Coil Vent Tube Pressure Drop
  • Parallel Ring & Bushing  Flow Test
  • Stator Test Wedge Measurements
  • Building & Through Bolt Tightness Check
  • Radial Clamp Tension Test
  • Top Coil Support Ring Checks
  • Bottom Coil Support Ring Checks
  • Impendance Test
  • Pole Balance
  • Insulation Resistance of Winding
  • Rotor Winding Resistance Measurements
  • Radial Lead Assy. Leakage Test [Nitrogen]
  • Radial Lead Seal Leakage Test [Helium]
  • Hardness Testing
  • Blower Hubs Hardness (solid shaft only)
  • Retaining Rings Hardness Testing

RTD Element Resistance Test

Thermocouple Continuity

RTD or T/C Insulation Resistance

Diode Wheel:

  • Fuse Testing
  • Diode Forward/Reverse Resistance
  • Capacitor Fuse Check (Mark III only)
  • Diode Wheel to Heat Sink Insulation Resistance
  • Diode Wheel to Exciter Shaft Insulation  Resistance
  • Diode Wheel-to-Diode Wheel Insulation Resistance

Exciter Rotor:

  • Winding Resistance
  • Winding Ring Insulation Resistance
  • Ground Detection Ring Insulation Resistance
  • Continuity of Ground Detection Ring to Armature
  • Rotor Ground Protection Insulation Resistance
  • Slip Ring to Ground Insulation Resistance
  • A Ring to B Ring Insulation Resistance

Exciter Stator Assembly:

  • AC Impedance & Pole Balance Test
  • Winding Copper Resistance
  • Winding Insulation Resistance
  • Field Current Limiting Resistor Resistance

PMG Assembly:

  • Winding Copper Resistance
  • Winding Insulation Resistance
  • Fiber Optic End Winding Vibration System
  • Rotor Flux Probe Monitor
  • Frame Foot Loading
  • GenAdvisor
  • Evacuating water from the generator windings is necessary for performing some electrical tests on the stator windings system
  • Extremely useful in Leak Detection and Investigations
  • Vacuum decay can be affected by moisture in system
  • Helium leak detection can be affected
  • Stator winding leak repairs
  • Aids in Long term storage of or layup of the stator water cooling system

Loop Testing is performed to identify and restore insulation between core laminations, (if interlaminar insulation has broken down).

  • Standard Loop testing is performed at an input  frequency of 60 Hz and a voltage of 4,160 VAC  (This tests the generator at rated flux density).
  • Once energized, the stator core is scanned with a Thermographic camera for evidence of hot spots.


High Frequency Flux Test

  • Magnetization of the stator core
  • Production of magnetic / core losses to detect hot spots in fault locations by eddy currents at 480 VAC inputs, rather than at 4,160 VAC.
  • Lower input Voltages and Currents allow for smaller cable sizes and customer demands.
  • The VFPS, (Variable Frequency Power Supplies) can be run as stand alone units, or run in parallel for larger generators if needed.
  • Thermovision scans are then performed similar to the 60 Hz loop tests but at variable frequencies, (usually around 500 Hz), to locate hot spots in the stator core iron. 
  • Power Factor Testing (Tan δ)
  • Partial Discharge Testing
  • Doble Testing

Modal analysis determines the natural 

frequencies and mode shapes of turbine-

generator static structures across the 

relevant frequency ranges of operation. 

Testing ensures that during operation the 

structure is tuned away from resonant 

conditions that increases structure fatigue 

and chance of failure. Modal analysis can 

be performed in the field or the factory.


Modal analysis applications include:

  •  Generator end windings
  •  Generator pedestals
  •  Generator frame
  •  Generator lead box
  •  Operational deflection shape (ODS)
  •  Blade frequency testing
  •  Turbine structural shaker test
  •  Rotor modal analysis
  •  Baffle plates

Further comprehensive Siemens Generator Service Capabilities can be offered upon request.


Getting in touch

If you have any questions or would like to find out how we can help you to modernize your generator equipment, please let us know.