1. Motor Testing (Motor Only)
(C) 2006, SUCCESS by DESIGN

2. Overview
IEEE P1415: “Draft Guide for Induction Machinery Maintenance Testing and Failure Analysis”
Key to Understanding Condition-Based Monitoring and Troubleshooting is to understand the capabilities and limitations of testing technology
(C) 2006, SUCCESS by DESIGN

3. Overview Focus of This Presentation Stator Winding and Core
Rotor Winding and Core
Vibration and Noise
Bearings and Shafts
Structure and Frame
Ventillation
Accessories
(C) 2006, SUCCESS by DESIGN

4. Condition-Based Technologies
AC High Potential
2Ev + 1,000V for new
% of nameplate for existing
Pass/Fail
Acceleration Time
Changes may indicate power supply problems
Trending if conditions are identical
Bearing Insulation
Evaluate for reduced shaft currents
Follow IEEE Std (up for re-affirmation in October, 2005)
(C) 2006, SUCCESS by DESIGN

5. Condition-Based Technologies
Bearing Temperature by RTD
Thermocouple or Bulb-Type
Temperature limits vary but generally fall in the range of C for alarm and C for shutdown
Higher temp limits for synthetics
Trendable with temp correction
Capacitance
Trended value
Surface contamination, high humidity, high temperature or general insulation breakdown
Effective for trending
(C) 2006, SUCCESS by DESIGN

6. Condition-Based Technologies
Core Loss (Loop Test)
During motor repair to detect inter-laminar insulation damage
No hot spots greater than 10C from ambient core temperature
If value shown: <6 Watts/lb and no change from before and after winding removal
Pass/Fail
Coupling Insulation
Ensure no shaft currents into driven equipment
IEEE Std
(C) 2006, SUCCESS by DESIGN

7. Condition-Based Technologies
Current, Demodulation
Used in ESA and MCSA as a method of removing the fundamental frequency from current FFT spectra
Trendable
Current, Running
Indication of load
Pulsating current, measured with an analog probe will indicate rotor faults
Not trendable
Current, Signature Analysis
Provides analysis of electro-mechanical condition and driven equipment condition
Analysis of current FFT spectra
(C) 2006, SUCCESS by DESIGN

8. Condition-Based Technologies
Current, Starting
Inrush and starting current is evaluated for anomalies
Trendable
DC High Potential
Trendable when leakage recorded
(2Ev V) x 1.7 new insulation
Value x for used insulation
A sudden increase in leakage current indicates a fault
(C) 2006, SUCCESS by DESIGN

9. Condition-Based Technologies
Dissipation Factor and Power Factor
Utilize AC at the rated voltage of motor
Trended value should not exceed a change of 2%
Grease Analysis
Used to trend and evaluate deterioration of lubrication properties
Trendable
Growler (explain where name from)
Used to evaluate the condition of rotor bars when the rotor is removed from the electric motor
Pass/Fail
(C) 2006, SUCCESS by DESIGN

10. Condition-Based Technologies
Insulation Resistance
Measures insulation value (leakage converted to MegOhms)
IEEE Std
Trendable
Oil Analysis
Used to evaluate the degradation of the lubricating properties of oil
Detect excessive mechanical wear
Partial Discharge
Measurement of capacitive discharges
Generally trended on machines over 6kV
(C) 2006, SUCCESS by DESIGN

11. Condition-Based Technologies
Phase Angle
The timed measurement between the peak voltage and current at about 7Vac applied to a coil
Compare two coils +/-1 digit from average
Trendable
Phase Balance (Z and L)
Used to detect severe winding unbalances
Detect inter-turn winding contamination
Compare phase to phase patterns between impedance and inductance
(C) 2006, SUCCESS by DESIGN

12. Condition-Based Technologies
Polarization Index
Ratio of 10 minute and 1 minute insulation resistance tests
A ratio of 2 or more is required on pre-1970 insulation systems
Trending required on newer insulation
Single-Phase Rotor Test
10% of motor nameplate voltage applied across one phase of motor
Rotor is turned and current values taken
Variations of 3% or more over 360 degrees of rotation indicate rotor bar fault
Not trendable
(C) 2006, SUCCESS by DESIGN

13. Condition-Based Technologies
Shaft Grounding Current
Measurement of shaft current
Trendable
Shaft Testing
Magnetic particle, liquid penetrant and ultrasonic examination used to evaluate condition of shaft material
Pass/fail
Shaft Voltage
Measurements taken from shaft of motor
Variations may indicate problems with the motor
(C) 2006, SUCCESS by DESIGN

14. Condition-Based Technologies
Speed
Uses measurements of motor RPM in order to determine if potential motor or load problems exist
Trendable
Surge Test
High frequency, high voltage impedance-based test to check turn-to-turn dielectric strength
Comparison of waveforms
Not trendable
(C) 2006, SUCCESS by DESIGN

15. Condition-Based Technologies
Surge PD
Variation of the surge test, evaluates partial discharges that result from the high voltage, fast rise-time test
Trendable
Thermography
Utilizes an infrared camera to compare the ambient to test component
Defects can cause a high temperature rise at the point of fault
(C) 2006, SUCCESS by DESIGN

16. Condition-Based Technologies
Torque Analysis
Uses three phases of voltage and current in order to calculate torque
Value is displayed and analyzed as torque FFT spectra
Trendable
Ultrasound/Ultrasonics
Used to detect bearing and other electro-mechanical defects in motors
Variable Frequency (I/F)
Using about 7Vac, the motor current is measured then applied frequency doubled and the resulting current compared to the first current
Displayed as a percentage, which should be no more than one or two digits from average
(C) 2006, SUCCESS by DESIGN

17. Condition-Based Technologies
Vibration
FFT spectra of vibration information is used to trend and detect mechanical and some electrical faults
Trendable
Voltage Unbalance
Voltage measurements detect voltage unbalance defects in supply
Less than 2% recommended, no more than 5%
Voltage Distortion
Harmonic content of voltage
If value too high, rotor and stator heating occurs
(C) 2006, SUCCESS by DESIGN

18. Condition-Based Technologies
Voltage Drop
Trended measurement of voltage drop when starting a large motor
Changes may indicate defects
Trendable
Voltage Level
Measurements used to ensure that the supply voltage remains +/-10% of nameplate
Voltage Spikes
Monitoring spikes allows the ability to evaluate supply and control conditions
(C) 2006, SUCCESS by DESIGN

19. Condition-Based Technologies
Winding Resistance
Used to detect broken wires and loose connections.
Trendable unbalance
Winding Temperature
Trended over time in order to determine if overload conditions or insulation failure may occur
Trendable
(C) 2006, SUCCESS by DESIGN