Joseph D. Gierlach Jr. Vice President ABM Franchising ... · Operating Parameters Transformer PHB...
Transcript of Joseph D. Gierlach Jr. Vice President ABM Franchising ... · Operating Parameters Transformer PHB...
Joseph D. Gierlach Jr.
Vice President – ABM Franchising Group ~
TEGG Service
Electrical Ultrasound - Past and Present
What assets are critical?How important can ultrasound be?
Can anything really be gleaned?
Electrical Ultrasound - Past and Present
We will discuss the 5 common faults in these components and review their spectral signatures
1) Arcing
2) Tracking
3) Corona (above 1000 Volts)
4) Mechanical Vibration
5) Mechanical/Electrical Looseness (Contact Chatter)
Electrical Ultrasound - Past and Present
Transformers are one of the most critical components in the
electrical system
Most often, they are not readily available in the event of a failure
It does not matter if it is a liquid filled or dry type unit, maintenance is key
to longevity, as the components are the same internally.
Electrical Ultrasound - Past and Present
Today’s example involves a unit similar to the ones pictured below.
The initial service was performed in October 2011
It is in a hospital in Ohio and was manufactured in October 2004
Electrical Ultrasound - Past and Present
Energized services were conducted in the beginning of
October 2011
This was a 2nd year visit to the customer in which assets
were maintained the previous year with no issues noted
The technicians obtained recordings of each winding in
question, along with a comparison of another unit under
similar operating conditions
Electrical Ultrasound - Past and Present
A Phase B Phase C Phase
Click each winding to play
This is what
they heard
Electrical Ultrasound - Past and Present
A Phase B Phase C Phase
Click each winding to play
There was a
sister
transformer
nearby for
comparison
recordings
Electrical Ultrasound - Past and Present
FFT display
illustrating
comparison
between the
two units “B”
Phase Coil
Clearly a
qualitative
difference
Electrical Ultrasound - Past and Present
Time Domain
for the suspect
coil
Electrical Ultrasound - Past and Present
Time Domain
for the
comparative
coil
Electrical Ultrasound - Past and Present
“Sliced” view of
the time on
suspect coil…..
Note the
differences in
the amplitude
of the peaks
and variations
in timing
Electrical Ultrasound - Past and Present
The FFT illustrated “fault frequencies” that were NOT 60 hZ harmonics,
which indicates something other than electrical
However, there was an abundant amount of “frequency content
throughout the spectrum…..something electrical
Electrical Ultrasound - Past and Present
With a 30 hZ harmonic cursor, the mechanical component can be seen
Although it is a small, negative type “peak”, not electrical
Electrical Ultrasound - Past and Present
Operating Parameters
Transformer PHB (Bad)
Winding 1 (A phase) = 870 amps
Winding 2 (B phase) = 877 amps
Winding 3 (C phase) = 960 amps
Square D , Power Dry II , Serial# 17157191-008-01 , Type=VPI
2000 KVA , class AA/FFA , Temp Rise 115 deg C
High=12,470 Volts
Low=480Y/277 3 phase LV
Amps=2406
Z=5.76
Exposure=Cat C , 12200 lbs Tapped at E&G
Manufacturer Date=10/1/2004
Transformer PHA (Good)
Winding 1 (A phase) = 830 amps
Winding 2 (B phase) = 830 amps
Winding 3 (C phase) = 890 amps
Electrical Ultrasound - Past and Present
Another good indicator that something was in fact occurring was the
comparative Infrared images………
Note the saturation on the suspect winding…(Dynamic range exceeded)
PHA (Good) PHB (Suspect)
Electrical Ultrasound - Past and Present
With the suspect winding “exceeding” the calibrated range of the IR
camera, we know the temperature is now higher 150 Degrees C…..
The thermal source is also within the winding itself on the vertical core
section, based on conductive heat transfer patterns.
PHA (Good) PHB (Suspect)
Electrical Ultrasound - Past and Present
With this evidence and supporting data, a shutdown was recommended to the
customer.
This would allow for further diagnostic testing as well as a thorough visual
examination to determine the root cause of both the ultrasonic emissions and
the elevated thermal energy present on the B Phase coil.
The electrical tests that would be necessary to determine if any damage has
occurred electrically would be as follows:
1. Insulation Resistance
2. Winding Resistance
3. Turns Ratio Testing
4. Power Factor Dissipation
Electrical Ultrasound - Past and Present
The electrical tests did not reveal any abnormalities and were within industry
standard limitations:
Winding resistances are within the balance limits of 1%
Electrical Ultrasound - Past and Present
The electrical tests did not reveal any abnormalities and were within industry
standard limitations:
Insulation resistances are within the Polarization Index requirements
Electrical Ultrasound - Past and Present
The electrical tests did not reveal any abnormalities and were within industry
standard limitations:
Turns ratio measurement are within the +/- 0.5% tolerances of the
calculated ratio and the adjacent windings
Electrical Ultrasound - Past and Present
Power factor dissipation measurements were within the NETA specified
limits, indicating no excessive losses through the insulation
Electrical Ultrasound - Past and Present
Visual Image
of the suspect
winding and
area of highest
emission
Electrical Ultrasound - Past and Present
This is good news for the customer, or is it……
The answer is “yes and no”……as the visual inspection reveals
something far more telling…….Can you spot the item of interest?
A Phase B Phase
Electrical Ultrasound - Past and Present
A Phase
Welded retaining strap to tightly join vertical clamping steel with
horizontal
Top Horizontal Steel
Vertical Clamping Steel –Outside Phase, Low Voltage
Side
NOTE: This joint is FLUSH, and the sections are even and flat
Electrical Ultrasound - Past and Present
B Phase
Clearly, these steel pieces are NOT flush, which indicates a distortion of the top horizontal section bowing out on the B Phase winding, low voltage side
Electrical Ultrasound - Past and Present
This is EXACTLY where the ultrasonic emission was at its greatest intensity!
Electrical Ultrasound - Past and Present
B Phase
Visual evidence of excessive heating on the core laminations, backing up what was observed with the infrared camera
Electrical Ultrasound - Past and Present
B Phase
Visual evidence of
laminate separation
within the horizontal
core piece
For perspective, a flat
head screwdriver fit
into this separation
“with ease”
Electrical Ultrasound - Past and Present
Lamination separating
even further into the
core toward the high
voltage side
Electrical Ultrasound - Past and Present
One more
indicating
thermal
effects on
the varnish
of the core
laminations
Electrical Ultrasound - Past and Present
Because the miter joint that
connects the center phase to the
top horizontal laminations is no
longer connected properly due to
the “bowing” of the joint………
The magnetic flux path becomes
“interrupted” or “disturbed” ,
thereby making it the most likely
cause of the ultrasonic emission
and leading to the additive thermal
heating
Electrical Ultrasound - Past and Present
The sister unit that was used for
the comparative recordings was
also examined
It is exhibiting signs of cracking in
the varnish
Because it is the same design, it is
safe to say it could be subjected to
the same problem
Electrical Ultrasound - Past and Present
A follow up visit to the location one
year later, and after multiple
conversations with the
manufacturer proves the issue is
still present…………….and
worsening
Click to play
It’s only a matter of time before the
electrical fault/failure occurs as a
result
Electrical Ultrasound - Past and Present
REVIEW OF TYPICAL MECHANICAL LOOSNESS
SIGNATURES:
1) Typically all fault frequencies up to 900 hZ on relative
frequency scale (offset from 60 hZ in this case)
2) Lacking “frequency noise” in between harmonics (not the
case in this example, electrical fault developing as a result of
the mechanical issue)
3) Time series has consistent, uniform amplitude bursts
ALL ARE PRESENT IN THIS EXAMPLE EXCEPT #1
**Delamination of the core pieces due to magnetic field
interaction, which led to winding insulation damage
Would you think a
simple 30 amp
240 volt circuit
breaker have an
ultrasonic
emission?
Electrical Ultrasound - Past and Present
Take a listen to
what was heard in
Atlanta Georgia…
Click Image to
Play
Electrical Ultrasound - Past and Present
This observation was supported by the infrared camera in this
instance…
Electrical Ultrasound - Past and Present
With moderate loading (72% of rating), the temperature was
almost 20 degrees C above the ambient air……….expect no
more than 10 degrees C
Electrical Ultrasound - Past and Present
With moderate loading (72% of rating), the temperature was
almost 20 degrees C above the ambient air……….expect no
more than 10 degrees C
Electrical Ultrasound - Past and Present
FFT comparison to a tracking sample reveals the nature of
the emission………………………electrical
Electrical Ultrasound - Past and Present
Larger view (Red = Known---------------White = Suspect)
Electrical Ultrasound - Past and Present
Time Series reveals signature inconsistencies in amplitude and timing of
events
Electrical Ultrasound - Past and Present
Sliced up it is even more convincing……………….
Electrical Ultrasound - Past and Present
Combination of
a bad internal
contact and line
side connection
issue was the
result as
evidenced by
the thermal
patterns
Electrical Ultrasound - Past and Present
Electrical Ultrasound - Past and Present
Another low voltage, 240 volt, double pole breaker……. 3-8-2010
Click to play
Electrical Ultrasound - Past and Present
Suspect breaker is feeding a critical load and running at 45% of rating
Electrical Ultrasound - Past and Present
FFT shows electrical in nature…
Electrical Ultrasound - Past and Present
Comparison to known sample, (fault in red, sample is white)…
Electrical Ultrasound - Past and Present
Full recording time series……
Electrical Ultrasound - Past and Present
512 ms view…….
Electrical Ultrasound - Past and Present
278 ms view (appx 25 cycles……. Clarity is achieved for tracking picture
Electrical Ultrasound - Past and Present
Another tracking event, only this is on a 50 hZ system……. 2-10-16
Click to play
Electrical Ultrasound - Past and Present
Balanced loads of 500 amps per phase, 1600 amp rating
Electrical Ultrasound - Past and Present
Surface temps are “low”………or are they……….INDIRECTLY
Electrical Ultrasound - Past and Present
At the source (i.e. contacts), temps are MUCH HIGHER…
Electrical Ultrasound - Past and Present
FFT Indicates has a familiar signature…..ELECTRICAL
Electrical Ultrasound - Past and Present
Some 50 hZ harmonics, rich frequency noise………. = TRACKING??
Electrical Ultrasound - Past and Present
We need the Time Series to determine exactly…..and we see on the
large view variations/inconsistencies in time and amplitude…..
Electrical Ultrasound - Past and Present
Sliced to ¼ second (appx 12 cycles), it is CLEAR now…
Electrical Ultrasound - Past and Present
REVIEW OF TYPICAL TRACKING SIGNATURES:
1) Several fault frequencies (not present in this case)
2) Abundant “frequency noise” in between harmonics
3) Time series has bursts or excursions throughout recording
period
4) The amplitude of the bursts are not uniform in nature
ALL ARE PRESENT IN THIS EXAMPLE
**Most likely arcing and tracking within the unit / contacts
respectively
Electrical Ultrasound - Past and Present
Maintenance Panel Circuit Breaker 3-2015, 60 hZ
Click to play
Electrical Ultrasound - Past and Present
Very similar FFT spectrum to tracking with a twist…..
Electrical Ultrasound - Past and Present
The 60 hZ harmonics are more abundant in the spectrum with
frequency noise…..
Electrical Ultrasound - Past and Present
The Time Series looks more like a mix of arcing and tracking ……
Electrical Ultrasound - Past and Present
Variations were due to changing load levels…..
Electrical Ultrasound - Past and Present
REVIEW OF TYPICAL CONTACT ISSUE SIGNATURES:
1) Abundant fault frequencies
2) Abundant “frequency noise” in between harmonics
3) Time series has bursts or excursions throughout recording
period
4) The amplitude of the bursts are not uniform in nature
ALL ARE PRESENT IN THIS EXAMPLE
**Most likely arcing and tracking within the unit / contacts
respectively
Electrical Ultrasound - Past and Present
UK Packaged Substation Arcing………..
Click to play
Electrical Ultrasound - Past and Present
UK Packaged Substation Arcing………..
Electrical Ultrasound - Past and Present
FFT shows no 50 hZ fault frequencies
Electrical Ultrasound - Past and Present
Full 30 second recording on time series shows a different story………
Electrical Ultrasound - Past and Present
Notices the bursts , total silence, then bursts again
Electrical Ultrasound - Past and Present
5 second sliced view……………………..
Electrical Ultrasound - Past and Present
2 second sliced view, far more pronounced and evident……………..
Electrical Ultrasound - Past and Present
REVIEW OF TYPICAL ARCING SIGNATURES:
1) Several fault frequencies (not present in this case)
2) Abundant “frequency noise” in between harmonics
3) Time series has large bursts and some apparent
periods of silence
**Contact degradation due to misalignment and/or
poor seating pressure
Electrical Ultrasound - Past and Present
One more with destructive corona, packaged sub 7-2009:
Electrical Ultrasound - Past and Present
Initial recording on top left of switch was made…
Click to play
Electrical Ultrasound - Past and Present
FFT shows some frequency noise but little fault peaks….
Electrical Ultrasound - Past and Present
Time series has some tale,tell signs of something familiar….
Electrical Ultrasound - Past and Present
We need a closer look with a smaller time base…
Electrical Ultrasound - Past and Present
2 Months later, another recording……9-2009, but a different location
Click to play
Electrical Ultrasound - Past and Present
FFT shows more pronounced harmonic and noise content
Electrical Ultrasound - Past and Present
Particularly when compared to previous recording
Electrical Ultrasound - Past and Present
Full Time Series looks similar, but greater amplitudes
Electrical Ultrasound - Past and Present
Intensity increase visualized on scale differences…….
Electrical Ultrasound - Past and Present
300 ms view of second recording
Electrical Ultrasound - Past and Present
300 ms view of second recording, again illustrating intensity
increase
Electrical Ultrasound - Past and Present
Shutdown was immediately scheduled for 2 weeks later, visual
evidence of the fault was observed
Electrical Ultrasound - Past and Present
Nitrates had materialized already, failure has begun…
Electrical Ultrasound - Past and Present
Destructive corona, as indicated by the Spectralyzer analysis is
confirmed and repairs completed…