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.

Visual Inspections

Completion of Lockout/Tagout procedure prior to entering the unit.

Electrical isolation and grounding of stator winding.

Implementation of Foreign object incident control.

Inspection of Stator Winding Components:

Visual inspection of the overall appearance of the stator windings. Looking for signs of dirt and/or oil, corona, tape separation, foreign objects, overheating, deterioration and any abnormalities.
Inspection of top and bottom diamond spacers for greasing and wear.
Inspection of coil to brace fillers for dusting or greasing.
Inspection of support ring spacers for dusting or greasing. Including bottom coil support ring, inboard bottom coil support ring, middle coil support ring, and top coil support ring.

Stator Core:

Inspection of the stator iron for general appearance and visible discoloration and evidence of hot spots or mechanical damage.
Inspection of the slot wedges for signs of looseness, dusting, or greasing, and migration of the wedges and/or wedge filler.
Inspection of the back of the core for fretting between building bolts,
Laminations and any other unusual circumstances.

Inspection of Abnormal Conditions:

Inspection for the evidence of OCP Erosion. (Outer Corona Protection)
Inspection for Coil Side Filler Migration.
Inspection for Wedge Movement, Greasing and Migration.
Inspection for evidence of electrical distress, deterioration and break down.

Main Leads and Bushings:

Inspection of the porcelain insulators.
Inspection of the interface of porcelain to flange seal inside and outside of the lead box, where accessible, for signs of greasing, gas or oil leakage.
Inspection of the leads for condition of insulation taping and voltage break down.

Generator Rotor:

Visual Inspection of the Retaining Rings.
Visual Inspection of the Radial Leads.
Visual Inspection of the Rotor Body.

Stator Electrical Tests

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

Stator Mechanical Tests

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

Rotor Electrical Tests

Impendance Test
Pole Balance
Insulation Resistance of Winding
Rotor Winding Resistance Measurements

Rotor Mechanical Tests

Radial Lead Assy. Leakage Test [Nitrogen]
Radial Lead Seal Leakage Test [Helium]
Hardness Testing
Blower Hubs Hardness (solid shaft only)
Retaining Rings Hardness Testing

Exciter Electrical 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

Siemens Energy has +30 years of providing robotic In-Situ generator inspections known as FAST Gen. The three inspection scopes offered are Visual, Siemens Multifrequency Core Assessment System (SMCAS™️) and Wedge Tightness. The visual inspection utilizes on board camera(s) that are capable of digitally recording video and still images used to look for visual signs of overheating, excessive relative motion, ventilation blockages in stator or rotor vent paths and possible foreign objects. SMCAS™️ is a test that evaluates core laminations for circulating currents the same as EL CID. A feature that SMCAS™️ offers is the ability to digitally overlay previously recorded SMCAS™️results to compare for trending over the life cycle of the stator core. Wedge Tightness testing is used to assess the loading force of generator stator wedges and is a helpful tool to predict a possible outage of sufficient length when loose or loosening stator wedges need to be replaced.

With 3 decades of field use comes significant innovation. Siemens Energy at the Pittsburgh Service Center has begun to incorporate additive manufacturing to the latest design updates that allow for more rapid customization of inspection components that can be attached to the modular base of the FAST Gen tooling or even complete standalone solutions. This enables the Pittsburgh Service Center to help meet an ever-increasing demand of non-OEM inspection requests where generator access may offer unique obstacles.

Diagnostic Instrumentation

Fiber Optic End Winding Vibration System
Rotor Flux Probe Monitor
Frame Foot Loading
GenAdvisor

Generator Stator Cooling Water System Evacuation

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

Generator Core Loop Testing

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.