Offline Rotating Machine Testing | EA Technology
+44 (0) 151 339 4181

Offline Rotating Machine Testing

Rotating Machines Condition Assessment Services

EA Technology’s Rotating Machines testing service can provide a comprehensive range of insulation diagnostic tests to assess the condition of motors and generators. Results can be used to identify machines at risk of catastrophic in-service failure, to improve performance and to extend reliable service life.

Rotating electrical machines (motors and generators) are often regarded as the most critical components in power generation and industrial production facilities where unplanned downtimes due to in-service faults can be very expensive. In order to prevent costly premature failures and to plan maintenance effectively, accurate and reliable condition assessment data is required. EA Technology’s full suite of state-of-the-art tests can help identify any issues so that you can make timely maintenance and repairs to prevent failure.

The Off-line Rotating Machines testing includes:

Partial Discharge (PD) Testing

PD measurement is widely regarded as one of the best methods for the assessment of the stator insulation condition. The PD allows for single weak spots in the insulation system to be clearly identified.

Capacitance and Tan Delta (Tan δ/DF/PF) Testing

To assess the condition of the bulk of the insulation and degradation over time.

Sweep Frequency Response Analysis

Allows to detect inter turn faults in the stator and rotor windings caused by mechanical stress.

Voltage Withstand Testing

A simple ‘Go/No Go’ test to identify weak insulation unsuitable for service.

DC Winding Resistance

Performed to detect any possible problems with contacts soldering and loose connections in the stator and rotor windings.

Insulation Resistance (IR) and Polarisation Index (PI)

To assess the condition of the stator and rotor insulation for contamination and moisture ingress using DC voltage.

Pole Drop Testing

To detect inter turn defects like short circuits in the rotor windings which could cause magnetic imbalance contributing to higher shaft vibrations and resulting stresses to the bearings.

Dielectric Response (FDS + PDC) Measurement

A very sensitive measurement to reliably establish moisture levels in solid stator insulation and detects levels of contamination.

As well as being an essential part of condition based asset management, Rotating Machine Testing should also be undertaken when a new motor or generator is commissioned as a fingerprint data collection for later comparison, following repairs and to diagnose faults. Regular Rotating Machine Testing, to identify faults early, will minimise expensive replacement costs as well as help to extend reliable service life of the rotating machine assets.


  • A full suite of state-of-the-art off-line tests on stator and rotor winding insulation.
  • Helps to avoid expensive in-service failures and downtime.
  • Provides essential data for cost effective asset management.
  • Highly knowledgeable and experienced diagnostic engineers.


Phil Smethurst
Business Development Manager

Get in touch

Thank you for your interest in EA Technology. You can request information or a free callback by clicking the link below. One of our experts will be in touch with you shortly.

Enquire Now