Studies by motor manufacturers indicate that 60% of electrical failures in motors begin as winding to winding shorts. Interturn shorts occur as insulation weakens and degrades due to temperature, voltage surges, mechanical damage during rewinding, motion, moisture and contamination. This degradation occurs in stages which may not be evident as a loss of motor performance.

ITR motor testing includes resistance checks, surge tests, winding comparisons, and hipot tests to assess the electrical condition of motors. The primary purpose of ITR motor testing is to identify developing and/or potential problems prior to catastrophic failure.

Traditional tests are unable to determine the condition of insulation between windings. Megohmmeter tests provide only the resistance of contaminants between a winding and ground. DC Hipot tests indicate the dielectric strength of the ground insulation. Although these tests are essential for thorough winding analysis, only surge testing completes the profile.

Surge testing applies a very brief high voltage pulse across the winding to stress the insulation. If the applied voltage is higher than the insulation strength between the turns, coils, and phases, the observed waveform will flicker, indicating a momentary breakover. When performed properly, this test will not further degrade the integrity of the insulation. The voltage at which the surge test failure occurs has a strong correlation to the remaining life of the motor.

Surge testing is also invaluable in diagnosing actual shorted conditions between turns, coils and phases in a three phase motor. The waveforms observed during testing exhibit distinct patterns for each of the short conditions. Analysts interpret the data and report with recommendations for corrective action, as needed.

Some characteristics of the ITR motor testing service worth considering:

• All ITR motor testers are electricians with industrial maintenance experience
• Average tester experience analyzing with ITR: 5+ years
• ITR ensures all motor test conform to IEEE standards
• Data and information integrated online via ITR information management tools

Motor Testing Service Specification and Deliverables:

• Full PdM program review/design by asset and PdM discipline
• Proprietary analysis and reporting technologies
• All testing conforms to IEEE 95-2002 and IEEE 43-2000
• Static testing includes:
• Initial resistance checks
• Megohm value determination of ground insulation
• DC hipot test
• Surge test
• Comparison test
• Dynamic testing includes:
  • Phase configuration test
  • Steady configuration test
  • Inrush “I” current test
• Special motor testing studies available upon request
• Identifiable problems:

Motor winding insulation degradation	Wiring comparison issues, including imbalance
Wiring degradation and connection issues	Dirt and moisture issues



• High risk / major issues reported immediately onsite for corrective action
• Full reports completed and issued within 5 business days
• Services customized to the customer’s internal processes as requested

Please contact us for more information or an onsite demonstration.