Download MPS Gaussbusters are proud to be “Safeguarding Machinery

MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Introduction to MPS
and
Monitoring of Shaft Voltage
and Shaft Grounding Current
in
Rotating Machinery
By
Paul Nippes, P. E. and Beth Galano
Magnetic Products and Services, 2135 Highway 35, Holmdel, NJ
Copyright 2007 Magnetic Products and Services
07733 USA
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
•
•
Founder and President, Mr. Paul Nippes,
P.E. has been consulting to
Petrochemical, Power Utilities and
Industry since 1965.
•
IEEE C50 Chairman for many years,
Cigre, ASNT and ASTM Contributor.
•
A Motor and Generator designer with Allis
Chalmers and Elliott Company, Electro
Dynamic Division of General Dynamics, a
Penn State Graduate and a Professor at
the University of Wisconsin.
In Paul’s Electrical Engineering consulting capacity, due to the frequency
of “bearing failures” in his consulting practice, Mr. Nippes championed this
research and developed products to provide solutions.
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
•
Areas of specialization…
9 Magnetism and the problems it can cause in Rotating
Machinery, Industrial Processes, or in any application.
9 Shaft Condition Monitoring - CBM using Stray Shaft
Currents and Shaft Voltages in Rotating Machinery for
Early Warning of Developing Faults.
9 Field Services – Degaussing, Magnetizing and Shaft
Voltage Testing
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
SHAFT CURRENT FROSTING
Shaft Journal
Bearing Pad
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
SHAFT CURRENT EFFECTS
Spark tracks
Copyright 2007 Magnetic Products and Services
Gear Pitting
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MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Electric Current Erosion of Thrust Bearing Pads
from a Turbine Driven Natural Gas Compressor
Spark Tracks
on the Active Pad Face
Pad Steel Backing Erosion
on Two Adjacent Pads
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Spark tracks Developing into Heavy Current Discharge Melting into the Babbitt
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Degaussing Turbine Diaphragms
Degaussing Blower Casing
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Demagnetizing Screw Compressor
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Auto Degauss
Auto “Down-Cycle”
Demagnetizing is Systematic
Removal of Magnetism
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Measuring Magnetism
MPS Gaussometer
Avoid Field Indicators (Magnetometer)
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Red – No Weld, Yellow – Maybe?, Green – Good to Weld
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
South China Sea
On Barge Vertical Pipe Welding Magnetic Field Stabilization
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Portable Magnetic Particle Inspections Applied to Military Impellors
Procedures Developed by an ASNT Level III (MPS Customer)
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Military Applications – Degaussing Solutions
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Shaft Voltage Surveys
Grounding Brush Performance Checks
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Failure Analysis and Solution Recommendations
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Carbon brush contact surface comparison
Normal
Glazed
Figure #4
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
1. Ground the Shaft
2. Check Grounding
Devices Often via
Local or Remote
Monitoring
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Grounding Brush Reliability is Critical
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
SHAFT CONDITION MONITORING (SCM) a Patented Technology
A continuous monitoring technology that uses shaft current and voltage profiles in
operating units for early diagnostics and prognostics to identify developing problems in
electrical and non-electrical rotating machinery.
Permanent Mount Monitors, Rack
Mount, Din-Rail Modules or
Sensors = Grounding Brushes
Hand-Held Monitors
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
MPS Signal Conditioning
VCM-E disposes of numerous and varying
frequencies and amplitudes for the purpose of
sensing only the important signal changes in
waveform fundamental frequency, peaks and
averages.
At the earliest changes and/or an excess in
these quantities, action can be taken to identify
and confirm possible problems.
Confirmation may include collection and
analysis of other unit operating parameters.
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Shaft Grounding And Voltage Sensing
Applied To Industrial Class Rotating Machinery
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
GENERATOR
HP TURB.
IP TURB.
LP TURB.
EXCITER
NO BRUSHES NO MONITORS AND NO PROTECTION
Shaft currents are not confined nor controlled.
Shaft current damage to bearings and seals is not prevented.
Bearing and seal oil films insulate against stray currents.
Stray voltages can damage unit or impair efficiency .
Events or oil impurities can establish electrical circuits.
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
GENERATOR
HP TURB.
IP TURB.
EXCITER
LP TURB.
SHAFT GROUNDING BRUSH
GROUNDING BRUSH, NO MONITOR, POSSIBLE PROTECTION
A quality grounding brush should discharge static electrical charge before damage occurs.
A quality grounding brush should establish good shaft contact protecting the nearby bearings.
The grounding brush could provide a return path for magnetically-generated current.
The brush may require maintenance, with loss of shaft grounding without warning
Damage can occur to bearings and/or seals if the generator outboard bearing insulation fails!
Shaft current damage to bearings and seals is first indicated by excessive vibration/temperature.
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Shaft Voltage Decrease And Current Increase Indicates Shaft Rub.
High Voltage At Sb#1, Inversely Proportional To Steam Temperature Indicates Wet Steam In Turbine.
High Current In Grounding Brushes And Low Voltage At Brush Sb#2 Indicates Loss Of Bearing Or Seal Insulation .
Rapid Escalation In Both Sb#2 Voltage And Grounding Currents Indicates Developing Stator Winding Fault.
Erratic And Pulsing Voltage And Current Indicate Stator Lamination Shorting And Melting .
Long Term Gradual Increases In Voltage And Current Indicate Shift In Air Gap.
Pulsing, Then Gradual Increase In Shaft Voltage And Current Indicate Rotor Winding Faulting.
Shaft Voltage Changes As Excitation Changes May Indicate The Need For A Shaft Voltage Harmonic Filter.
Trending Of Each Brush Grounding Current, With Maximum Current Alarm On Each Brush.
Each Brush Will Alarm On Low Brush Grounding Current Indicating Brush Or Grounding Maintenance Required.
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Oscilloscope recordings
taken from the identical
shaft grounding current
but with different voltage
and time scaling.
Upper trace =
112mV @ ~ 70MHz
Lower trace =
720mV @ ~ 80Hz
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Erratic grounding on shaft (Voltage source = The blower motor)
Ungrounded OB end – similar to IB end
OB trace, IB end Ground brush skip
Ungrounded IB end – similar to OB end
Grounded IB end skip not apparent
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Oscilloscope trace of
shaft grounding current
composed of a 60Hz
fundamental plus a strong
common mode bucking
third harmonic.
Characteristic of
magnetic saturation
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Effect on shaft of Electromagnetic
Voltages, determined from different
resistances in the shaft grounding cable.
Ungrounded (40 Volts)
1k Ohm (40 Volts)
100 Ohm (25 Volts)
10 Ohm (5 Volts)
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Effect on shaft of electrostatic
voltages determined from different
resistances in the shaft grounding cable.
Ungrounded (30 Volts)
10k Ohm (4 Volts)
1k Ohm (0.5 Volts)
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
CHART SCALES - ZERO TO 1.0 VOLTS AND 10.0 AMPERES
BRUSH CURRENT
ONE HOUR
750MW GENERATOR VCM OUTPUT INDICATING A
UNIT OR SYSTEM RECURRING CONDITION
Figure #11
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Ground Fault Condition at a Nuclear Power Plant and Root Cause
Copyright 2007 Magnetic Products and Services
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MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Root
Cause
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Unit 1 Shaft Peak
Currents and
Voltages for Six
Days
Grounding brush
Currents = 3.1 and
8.7 Amperes
Generator OB End
Shaft Voltage = 23.4
Volts
Turbine Shaft
Voltage = 0.2 Volts
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
Unit 2 Shaft Peak
Currents and Voltages
over a Day
Grounding brush
Currents = 2.2 and 6.7
Amperes
Generator OB End
Shaft Voltage = 14.0
Volts
Turbine Shaft Voltage
= 4.8 Volts
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
500 MW
Turbine
generator
Recorded Field
Voltage and
Peak Shaft
Grounding
Current
During a Field
Ground Fault
Figure #14
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
SCModules, Either Voltage
or Current, Battery or
AC Power, Local Alarm Indications; Remote Analysis
VCM-EN-SII Single
Enclosure Housing Two
Separate VCM-E
Boards/Circuits For
Large Or Critical Units.
Hand-Held VCM or SCMeter
or use with SCModules, Displays
Voltage or Current Peaks and Averages
Also Available…
(Explosion-proof
Models)
VCM-E, AC Powered, Local
VCM-C, Battery Power,
Local Display, Ungrounded
Peak-Voltage And Grounded Peak and Average
Ground Current, Max I = 3 Amps. Industrial Type
Applications.
Display, Alarm LED’s of Shaft
Grounding Current And Shaft Voltage.
Continuous Signals via 4-20 mA for
use in Control Room, via wired or
wireless connections.
VCM-EN-RM
Rack Mount Model
configurable with 1 to 4
VCM-E units.
MPS’ Family of Shaft Condition Monitors…for
Early Detection of Rotating Machinery Faults
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
SHAFT MONITORS provide Early Warning…
•
Grounding Brush or Ground has lost continuity.
•
Wet steam conditions at the exhaust end of the turbine
causing charge separation with possible blade erosion
and cavitation.
•
Dry Steam conditions at the inlet of the turbine with partial
admission, caused charge separation and spark
discharge.
•
Self Excitation or compounding of shaft voltages and
grounding currents from shorted rotor coil.
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
SHAFT MONITORS provide Early Warning…
•
Shaft Rubs at bearings, seals due to oil whip, coupling
misalignment, thermal growth, loss of lubrication, impurities in
the oil, etc.
•
Diode Failure in Generator Excitation.
•
Intermittent Rotor Winding Ground Fault
•
Loss of or Shorting of Insulation at Bearings, Seals, Gear Teeth
and Coupling, etc.
•
Excessive transients in pulse width modulated rotor and/or
stator electrical supply.
•
Stator core lamination shorting in an electrical generator.
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
•
Simplicity and Value - SCM reduces data to basic terms (a fraction
of the digital data), while still preserving critical data events
•
Supported by technology and performance of units installed in
the Utility and Petrochemical Industries.
•
Offers significant enhancement to PDM and Prognostic programs
of Utilities, Industry and the Military.
•
It could be an important input to the decision-making process
as to whether a rotating machine is Operational or “Service”
Ready.
•
Alerts at earliest possible problem development requiring
•
•
•
confirmation,
investigation
and possible parts replacement
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com
MPS Gaussbusters are proud to be
“Safeguarding Machinery Worldwide”
CONCLUSION
•
SCM Provides Early Warning of Rotating Machinery
Problems by Consolidating Signals to the Critical Data And
Power Components of the Signals.
•
Application To Machines Requiring Shaft-riding Brushes
And Reliable Monitors.
•
Integration into existing DCS or CBM systems is
straightforward and beneficial.
Copyright 2007 Magnetic Products and Services
www.gaussbusters.com