Maintenance and reliability training, innovation and education
Hilton HammondFluke Corporation
KPI’s to Help Improve Motor Health
2© 2018 | Fluke Corporation.Company Confidential.
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3© 2018 | Fluke Corporation.Company Confidential.
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Fluke TiS75 Thermal ImagerWith professional grade 320x240 resolution, a distance to spot (D:S) ratio of 504:1, and precise manual focusing, the TiS75 enables maintenance professionals to pinpoint issues with equipment and electrical systems quickly and accurately.
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4© 2018 | Fluke Corporation.Company Confidential.
At the conclusion if this session you will be able to:
● Assess the complex drive system in its individual parts, identify key measurements and tests in order to;
○ Uncover hidden problems or investigate root cause of symptoms before they lead to downtime
○ Identify leading indicator measurement variables to gauge the performance and health of the motor drive system
Objective: KPI’s to help improve motor health
Prevent failures, increase reliability and maximize motor lifespan
5© 2018 | Fluke Corporation.Company Confidential.
Most industrial motor drive systems operate in CAT III environment as defined by IEC 61010. (Fixed installed 3 phase loads or distribution equipment)
Safety First: Before we begin - a note on safety
● Test equipment must meet the category rating, area and working voltage, for e.g. 600V CAT IV or 1000 V CAT III
● Ensure the meter used is independently verified and not just “designed to meet?”
6© 2018 | Fluke Corporation.Company Confidential.
● Confirm the test equipment is rated for the use.
○ Installation Environment and working voltage
● Use proper PPE
Three phase systems in Cat III environments
● Mixing CAT III instruments with lower rated accessories
● Short circuiting floating differential test points with a common ground or device with non-isolated inputs
● Holding the meter during testing
7© 2018 | Fluke Corporation.Company Confidential.
Best practices for maintaining health of motor drives
8© 2018 | Fluke Corporation.Company Confidential.
Motor Drive System Failure Modes
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Complex System Electrical Tests & Metrics
10© 2018 | Fluke Corporation.Company Confidential.
Uncover hidden problems before they impact the drive
Validate power quality and power capacity
● Under voltage due to overloaded circuits ● Over voltages as result loads dropping
offline and/or efficiency improvements● Voltage events (Dips, Swells or Rapid
Voltage Changes from switching loads or PF correction equipment
● Voltage Unbalance● Harmonic Distortion
● Loss of power to motor● Excess heat and eventual motor winding
insulation failure● Random drive shutdowns● Excess heat dissipation in drive and other
inductive components
11© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke-438-II Power Quality and Motor Analyzer1. PQ Monitor (According to EN50160) – Log state and resolve
out of tolerance deviations● Frequency● Voltage Variations● Harmonics● Unbalance
● Events
2. Energy Study – Trend Over Operating Cycle● Max, Min and Average Power● Max, Min and Average Voltage, Current, Frequency, THD% and
Unbalance%● RMS Power Trend Graphs. Identify peak point during operating cycle
Validate power quality and power capactiy
Tip: Power consumption is never static – log data over entire process operating cycle – repeat periodically
12© 2018 | Fluke Corporation.Company Confidential.
Compare input power to drive rated specification
Verify input power is within drive operating specification
● Voltage deviation >10%● Frequency drift > 0.5 Hz● Voltage drop due to undersized circuit or
feed conductors● Current exceed max drive rating or motor
rated current (+ Service Factor)● Voltage unbalance >2% and Current
Unbalance >6%● Excessive total harmonic distortion (THD
>6%)
● Drive errors and potential resets● Overloaded input circuit and potential
rectifier failures● Loss of power● Elevated operating temperatures
13© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
1. RMS Measurements● Voltage● Current● Frequency● % Unbalance
2. Waveform Qualitative Analysis● Signs of “flat topping”● Distortion● Abnormal Fluctuations
Verify input power is within drive operating specification
14© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
3. Input Harmonics● Overall % THD● Harmonic Number Amplitudes
4. Check for Supra Harmonics● Validate performance of regenerative drives with
active front ends● Identify higher order frequencies that may be
disruptive to nearby communication equipment
Verify input power is within drive operating specifications
Tip: Compare current harmonics to voltage harmonics – if there are no current harmonics but voltage harmonics is excessive, investigate other loads on same circuit
15© 2018 | Fluke Corporation.Company Confidential.
Verify the operation of the inverter AC to DC to AC (pulse width modulation)
Check drive performance
● Low DC Bus Voltage● Excessive DC bus ripple voltage● Out of range output voltage, current and
frequency● V/Hz Ratio deviation from nominal● Current exceed motor rated current (+ Service
Factor)● Excessive voltage and current unbalance
● Drive errors and potential resets● Loss of power● Increased motor winding harmonic
distortion dissipate in form of heat● Elevated operating temperatures● Loss of operating performance● Motor decreased operating lifespan● Increased mechanical vibration and
component wear and tear
16© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
1. DC Bus Measurements● DC Voltage equal to ~1.414 x V rms input● DC Ripple under load: (base line when in known
good working condition)
2. Waveform Qualitative Analysis● Unstable DC Voltage● Ripple voltage amplitude and pattern changes
over time caused by failing capacitor or rectifier impedance change.
● Abnormal Fluctuations
Check drive performance
Tip: DC Bus voltage issues can be as result of input power, rectifier or capacitor bank problems. Eliminate input power by checking for flat topping and voltage events (dips, swells etc)
17© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
3. Output Nominal Voltage Current & Freq● Check measured parameters to motor name
plate for any out of range parameters● Check if V/Hz ratio is within specified limits for
the applications (Variable or constant torque)
Check drive performance
Tip: Use the Fluke Motor Drive Analyzer recording function to plot the V/Hz ratio over the equipment operating cycle
18© 2018 | Fluke Corporation.Company Confidential.
Check output PWM waveform for any abnormalities that lead to winding and/or bearing failure
Check drive pulse width modulated waveform
● Excessive peak voltage reflections ● PWM, pulse dv/dt ratio (Change in voltage
over change in time) exceeds motor winding rating
● Motor winding insulation degradation and eventual failure
● Stray earth leakage currents causing random ground fault interrupts
● Voltage discharges across bearing surfaces leading to premature wear
19© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
1. Overall PWM Characteristics● Effective voltage delivered to windings (Vpwm)
compared to programmed voltage● Output Frequency● V/Hz Ratio
Check drive performance
Tip: Capture and compare the PWM waveforms (Zoom 1, 2 & 3) at the drive output and motor input to verify cable installation
20© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
2. Peak voltages exceed winding insulation breakdown voltage rating
● V pk < winding insulation breakdown voltage rating
● NEMA MG1 Part 31, 2006 calculation for peak voltage = 1.1 * 2 * √2 * V rated
3. Trend PWM Pulse overshoot over time● % Overshoot
Check drive pulse width modulated waveform
21© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
4. Insulation stress as a function of pulse rise time and peak amplitude
● dv/dt ratio or the pulse edge amplitude increase in volts per second
● The dv/dt ratio should be within the manufacturers specification or motors manufactured in accordance with
○ NEMA MG1 Part 31 2006 or○ IEC 600034-25
Check drive pulse width modulated waveform
22© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke MDA-550 Motor Drive Analyzer
1. Fast voltage discharges across bearing surfaces
● Check for excessive counts/s of fast discharge events
● Industry experts suggest >6 Volts may be problematic
Check for shaft voltage discharges
Tip: Check periodically as bearing lubrication, load and other factors can influence the rate and occurrence of discharge events
23© 2018 | Fluke Corporation.Company Confidential.
Check motor load given the condition of the electrical power quality and mechanical installation
Assess motor load under operating conditions
● Poor power quality like unbalance, harmonic distortion and load conditions impact power transferred to motor shaft
● Operational changes exceed motor load rating
● Driven component wear or obstructions overload motor
● Loss of power and operating performance● Shortened motor lifespan● Potential shutdown● Excess operating cost or waste (kW/hr to
run motor)
24© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke 438-II Power Quality Motor Analyzer
1. Electrical characteristics compared to motor rating
● kW electrical power● Power Factor● % Unbalance● Harmonics
2. Mechanical characteristics compared to motor rating
● HP, mechanical power● Torque● Speed● % Efficiency
Assess motor load under operating conditions
25© 2018 | Fluke Corporation.Company Confidential.
Measurement KPI’s using Fluke 438-II Power Quality Motor Analyzer
3. Directly coupled motor’s derating factor according to NEMA guidelines
● Total derating factor
4. Trend derating factor over the complete operation cycle
● Load vs. Derating Factor historic cross hair marker plot should not traverse into red overload zone
Assess motor load under operating conditions
Tip: Take action to reduce cost or increase reliability by periodically checking % load and NEMA Derating factor (Under or over loaded)
26© 2018 | Fluke Corporation.Company Confidential.
Capture, Trend & Document Measurement Metrics
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Available resources to learn moreVisit us at the Fluke Booth
www.fluke.com/mda500series
Thank you!
28© 2018 | Fluke Corporation.Company Confidential.
12:00pm - 2:00pmRoyan and Sabal
Enjoy great food, networking and exhibits during this extended lunch break
Join us for lunch