Test & Inspection for Machine Status Assessment (TIMSA)

Advanced inspection program to reduce risk of failure on MV/HV rotating machines

An effective and proactive approach for your rotating machines

Within our rotating machines health monitoring offering, GE’s advanced TIMSA program is the most effective and proactive test and inspection approach for both your motors and generators. With this inspection program, we will identify any critical issues in your equipment and offer best solutions to fix them before a failure occurs. The inspection will be performed by fully trained and highly skilled field service experts, giving you the best assessment of your unit health status and the key actions to maximize its life expectancy.

Following inspections, GE can provide repairs and field services support, including [parts] replacement, to help you reduce risks and optimize your maintenance costs.
GE will carry out a series of electrical and mechanical tests with excelling safe work practices, on a periodic basis adapted to your business imperatives.

But not only can we inspect your GE and non-GE rotating machines; our team of expert field service engineers will also inspect any other peripheral control, protection or instrumentation system related to the rotating machine, that you may want to include in the outage.

We offer a wide range of tests

Essential tests

We perform all essential tests below to detect abnormalities in stator winding. Indeed, all traditional methods fail in detecting stator winding problems while this represents a major cause of MV/HV rotating machine failure:

  • Internal Visual inspection or boroscopic – to get a visual expert assessment of winding and core health.
  • Recording & analysis of operating data – to measure voltage, current, temperature, vibration, etc.
  • Insulation resistance test (IR) - to verify winding to ground resistance and check it is above the minimum acceptable value.
  • Polarization index (PI) – to assess cleanliness of the winding. Permissible PI is 2.0 and above.
  • Dielectric Discharge (DD) – to diagnose aging and deterioration of stator insulation.
  • RLC measurements – To check that winding is compliant with original technical specification.
  • Step Voltage (SV) – As stated in IEEE 43 § 6.4, this test assesses the winding dryness and general condition.
  • Surge test – Conducted as per IEEE 522 standard to assess the inter-turn integrity of winding by fast rise wave comparison.
  • Partial Discharge (PD) measurement 1 - To measure the winding’s response to a specific stress level and to predict its future performance.
  • Dissipation factor (tan δ) measurement 1 – To evaluate the quality of the stator winding’s insulation.
General Electric

These extra inspections will check mechanical integrity of the rotating machine components, giving you rounded integral insight on your rotating machine health status:

  • Bearing inspection – Open inspection on bearing journal surfaces, to measure and verify clearances.
  • Vibration analysis – To identify signs of wear and tear in advance to avoid very expensive damages.
  • Bearing oil analysis – To determine the overall service conditions of a bearing system and identify issues before a failure occur

We will recommend other tests specific to your business conditions that you may require, such as:

  • Dissipation factor measurement;
  • Offline partial discharges measurement;
  • Acoustic measurement;
  • CT/VT characteristics analysis;
  • Stator wedge mapping;
  • Resonant Surge Oscillography;
  • Online harmonic component analysis;
  • Etc.

We will deploy experts to inspect any other control, protection or instrumentation equipment connected to the rotating machine, that you may want to include in the inspection, providing integral inspection service recommendations, with a global system view. These may include, among others:


Customer will receive a final report with the expert assessment of GE Engineering Office.

Standard inspection formats

  • Minor inspections: Lowly invasive electrical tests and boroscopic inspections, without exposing unit winding, completed typically in 1-2 days, usually repeated every 1-3 years.
  • Major inspections: On top of minor inspection testing, unit end shields are opened, exposing winding for direct thorough inspection and cleaning. Extra mechanical checks are added for bearings, fans, and other rotating components. These are typically completed in 3-7 days. Usually repeated every 4-6 years.
  • Rotor out inspections: On top of major inspection tasks, the rotor is threaded out of the stator for full winding inspection and cleaning, as well as extra testing. This level of inspection is recommended ad-hoc, usually takes 7-15 days, and is performed every 10-15 years.


  • OEM backed unit health status assessment.
  • Inspection tailored to your specific unit needs;
  • Expert recommendations on best actions to maximize your asset lifetime and optimize your service expenditure;
  • Integral maintenance and repairs service