“Something for nothing” hits pay dirt!
Joseph D. Gierlach Jr. ~ Vice President, Technical Training and Support
TEGG Corporation ~ Pittsburgh, PA
ABSTRACT:
It has been said by wise men that, “the best things in life are free.” This statement can be very
hard to accept in today’s competitive world, and it can be argued that there is nothing left in life
that is free. Occasionally, though, we see glimpses of this that can lead to revelations which
prevent catastrophe and forge relationships between contractor and customer that will last a
lifetime. This paper covers a recent case study in which a simple service led to the discovery of
a major deficiency that surely would have resulted in a failure in a large food processing
facility. The irony of the story is that the component was not part of the original inventory of
components, and the fault was identified simply by taking one extra step out of curiosity. The
results are unmistakable, and reinforce the fact that going the extra mile and giving “something
for nothing” can and does pay dividends.
INTRODUCTION:
With the demands on electrical systems and components in the 21st century, reliability, uptime,
reduced operating costs, longevity, and consistency have become paramount considerations.
One cannot afford to have an interruption in supply power, let alone the failure or destruction of
a component in a system that provides the life blood of any given facility. Interestingly, though,
a paradox had developed with respect to maintenance by depending on system performance
and reducing allocations in budgets. There is nothing that will last forever without some
attention focused on prevention to foster that reliability and performance desired. Insanity has
been characterized as “doing the same things over again and expecting different results.” This
is a fitting description of some maintenance philosophies where the mentality is that less
attention will not contribute to equipment failures or “if it ain’t broke, don’t fix it.” Not all facilities
have the resources or contingency plans in place for a “run to failure” operation; however, for
those who fit this category, a well administered maintenance program aids in not only lowering
operating costs, but increasing the MTBF of components.
Doing more for less has become the most common theme throughout the industry, and
managers are faced with the challenges of stretching their resources, including budgets and
personnel. This can become taxing as the demands grow and possibly lead to shortfalls with
unintended consequences. Manufacturing processes of any type, such as metals, plastics, or
even food products, require continuous operation that cannot suffer disruption, as this could
cause a chain reaction event that could render an entire run or batch useless or scrap. This is
not a good scenario for the bottom line of any company if the goal is to maximize profit
margins.
CASE STUDY:
Recently, one such event took place at a bacon processing plant in northeast Ohio. A major
processor of food products implemented a maintenance agreement with Advanced Electrical
Testing and Preventative Maintenance, located in Canton, Ohio. Work commenced at the
facility in June of 2008 and was performed by Jeff Hinton and Jerry Bennett, lead technicians
who have been performing TEGG services for about a year. The inventory on this particular
site consisted of 222 components, so there was enough service to keep the technicians on site
for a couple of weeks, and time would be of the essence.
Jeff Hinton
Jerry Bennett
Throughout the application of the service, a number of deficiencies were identified and
documented. A summary of the classes included 19 infrared, 42 electrical, and 1 ultrasonic
problem. Interestingly, the one ultrasonic class problem just happened to be located within a
12,470 VAC safety disconnect switch (similar to Figure #1 below) feeding a primary side of a
main service, oil-filled transformer with a 480 VAC secondary, and this was one of two major
components that did not make the inventory list. Additionally, this was a parallel service that
had two identical switches and transformers side by side.
Figure #1
As is typical with higher voltage classes of equipment, there is an inherent danger with opening
the equipment while energized, so this is not a common practice. Manufacturers will include
electrical and/or mechanical interlocks to prevent this from taking place; a prudent measure
given the risks. It is difficult, if not impossible, to perform maintenance on equipment such as
this without gaining access to the interior section. A more acceptable course of action would be
to secure a shutdown of the equipment, administer several industry standard tests, install
properly sized and placed infrared windows, return to service, and then use thermography to
ascertain operating health.
Through discussions with the customer contact, Jeff and Jerry were able to get some
background on the two identical disconnects. The one switch had been rebuilt in 2006, with
new hardware and terminations. Anyone who works on this type of equipment knows that it is
an art to properly terminate high voltage cables. Improper installations can and have resulted
in failures, which is never a pretty sight, is costly, and generally has collateral damage of other
components.
Being the conscientious technicians that Jeff and Jerry are by nature, they decided to listen to
the switches with the ultrasonic probe using both the airborne scanning module and the
contact attachment. Up on the mezzanine servicing the Main Distribution Panel, there were the
two switches, one fed by the 12,470 VAC coming in from the utility, and the other tapped from
the line side of switch number one. The vented bottoms of the enclosures made the use of the
airborne scanning module elementary.
The first switch appeared normal as one would expect - very quiet with only ambient and
competing ultrasound present. The second switch “surprised” the technicians with respect to
tonal quality and also intensity. The emission from this device was a very familiar audible
sound that Jeff and Jerry have heard many times through their training and work in the field. It
appeared to them to be tracking of some sort, or possibly a mechanical vibration. A thorough
visual inspection of the enclosure soon ruled out any loose tags, nameplates, hinges or
propagating emissions from the transformer that was close by.
It did not take long to confirm that what they were dealing with was in fact an electrical
anomaly originating from the interior of the second disconnect safety switch. Jerry quickly
made several recordings of each switch, as comparisons of similar components are crucial to
making sound judgment calls. Seeking a second opinion, he also reached out to me through a
phone call and we discussed his observations. The recordings were sent for analysis, and in
Figure #2 below are the frequency spectrums of the two switches.
Figure #2
The red trace illustrates the first switch in which there were no ultrasonic emissions present.
The white trace is the recording of the second that clearly has an anomaly. The frequency
content in between each 60 Hz peak is clearly more evident, the amplitude of the frequency
peaks are much higher in intensity, and the 60 Hz peaks begin to “disappear” on the outer part
of the spectrum, suggesting not corona only, but destructive corona with tracking. Nuisance
corona in this type of equipment would not be uncommon, however, when the 60 Hz peaks
start to disappear on the outer portion of the spectrum, this indicates that “electrical
discharges” are now taking place, better known as tracking.
The time domain is even more telling in this example, as it truly illustrates why comparison
recordings have so much value in identifying problem items. Everyone knows that as we have
intermittent discharges relative to tracking, there are more inconsistencies in the time domain.
One would expect that the characteristic “band” of white noise would be present; however, the
amplitude and spacing (more specifically, timing) should be uniform in this tool and recording.
As evidenced by Figure #3 below, this is clearly not the case.
Figure #3
Although we can see that there is an abundance of white noise throughout the recording, the
“excursions” that take place suggest no uniformity in spacing at all, which is our tell-tale sign of
electrical discharges due to the timing of the events. On the non-deficient switch, this becomes
even more transparent and is illustrated in Figure #4 below.
Figure #4
This is the more atypical time domain spectrum of a properly functioning electrical component
of this type. There is minimal content throughout the recording period, with the minor
exceptions of two excursions that represent an adjustment of the instrument’s contact module
for positioning purposes. The above represents what one expects to “hear” when applying the
ultrasonic instrument in the electrical arena, notwithstanding the obvious items such as
transformers, contactors, and variable speed drives, to mention a few.
By comparing these two recordings, it became even more evident that something was taking
place in the second switch that could be nothing short of imminent failure. Action had to be
taken as soon as possible with this discovery.
After consulting the customer contact and presenting the exculpatory evidence and findings,
the recommendation was made that a shutdown should be scheduled to open the switch to
investigate the suspicions related to the destructive corona. The customer agreed, and a plan
was devised to secure this outage on July 4, 2008. As this was a holiday weekend, everything
came at a premium, so our analysis had to prove correct.
Jerry and Jeff made preparations over the next week by securing all the parts for this particular
switch that might be needed - tools, temporary grounding clusters, lock-out / tag-out items, and
a coordinated plan with plant personnel and the utility supply to ensure a smooth and safe
transition to the de-energized service.
Finally the day arrived and work began early that morning. After working with plant staff to
secure the removal of source power, verify the absence of power, and lock out all the
applicable components, it was now time to open the suspect switch. All were curious as to
what would be revealed, as this remained a hypothesis based solely on the recording and
spectral analysis until now. In a matter of moments, it was crystal clear that our diagnosis was
right on target. The visual inspection quickly uncovered two major deficiencies that could have
never been identified while in operation and undoubtedly would have failed at some point.
First, the A and B phase knife contacts on the line side of the switch were only seated into the
clip approximately ¼”, barely making contact for the size of the service. This contributes to
high resistance connections which produces additive levels of thermal energy; however, one
could not see this without opening the door (not a recommended protocol due to the voltage
potential) or the benefit of infrared windows (not installed at this site). Absent this observation,
the switch would have more than likely remained in service, continued to deteriorate, and
ultimately experienced a failure due to this. Line side knife contacts are seen in Figure #5
below.
Figure #5
Full Switch View
Close Up of A & B Phase
You can see by the close-up view above that the left (A Phase) contact is not seated properly
compared to the right (B Phase) contact knife. Comparative ductor measurements indicated a
deviation that was simply not within the acceptable limits, so the technicians exercised the
switch blades four (4) times before the knives would seat properly, assuring good, low
resistance connections. Cleaning, burnishing, lubrication, and a retest of the contacts verified
that the repair actions were successful, with all values now within tolerances.
This was not, however, the source of the ultrasonic emissions identified and recorded two
short weeks ago which predicated the outage and maintenance efforts. The source was close
by, though, and did not take long to deduce the course of action. The conductors in this switch
were cotton jacketed SRML type insulation which connected the load side of the switch to the
pin bushings of the service transformers. The conductors were all routed through a dielectric,
mica board to allow for securing the wires and provide separation of magnetic fields.
The white, powdery residue that is typical of the nitric acid formed when destructive corona
releases nitrates into the oxygen was clearly present on these conductors and mica board.
Nitric acid both degrades and destroys electrical insulation and insulators, allowing discharges
along the insulator path that ultimately seek a path to ground and cause a flashover. This can
be seen below in Figure #6.
Nitric Acid Residue
Figure #6
This left no doubt that insulation breakdown had occurred and the integrity was compromised,
setting the stage for an explosion to eventually manifest. A failure of these conductors surely
would not be contained to this area and would initiate a chain reaction that would impact not
only the conductors, but the switch itself, the service transformer, and possibly the downstream
components supplied by this transformer due to their close proximity.
Repair work continued, and the load side conductors were removed to measure the length of
the replacement runs. Further evidence of the discovery and heating effects (suggesting
current flow to ground…) can be seen below in Figure #7.
Insulation Breakdown
Figure #7
The conductors were extremely difficult to remove from the mica board due to swelling of the
insulation and effects of the nitrates and heat! Evidence of thermal heating was apparent on
the conductors; however, this would have NEVER been identified with even the best of the
infrared cameras on the market, as there were no IR windows installed on this equipment.
Indirect measurements of temperature and thermal energy can be very misleading, as the
source energy can be hundreds or even thousands of degrees higher than what a camera
would detect on the outside of equipment such as this.
The new conductors were cut to length, mica board cleaned of all residue that could contribute
to a path for current flow to ground, all connections were tightened and torqued to
specifications, and the entire service completed on a July 4th holiday with the customer close
by to witness the efforts. Once the repair and replacement of the conductors was completed,
the final checks with a ductor were performed to ensure that good, solid electrical connections
were present to minimize the heating effects of the passive points. Figures #8, #9, and #10
show the end result as a marked difference from what was found.
Figure #8
Figure #9
Figure #10
Upon completion of this final task, the procedure to restore the utility supply was initiated. Plant
personnel worked with Jerry and Jeff to return the two switches and transformers to service
and get the normal loads back online.
Once this became a reality, one final task remained, which was to verify the repairs under
normal loads with the ultraprobe. With guarded anticipation, the rescan of the units was
conducted and the results were as one would expect. Jerry characterized what he determined
by saying, “it is quiet as a church mouse.”
This is the ultimate validation of both the repairs that were performed, as well as the initial
diagnosis with the ultraprobe. Although the units were not part of the preliminary inventory, the
discovery of the ultrasonic emission and subsequent analysis with the spectralyzer software
indicated a major problem that needed attention. When presented to the customer, the
evidence had to be convincing, as it was on a “sight unseen” basis. The proof became the final
product.
SUMMARY:
Maximizing both uptime and equipment longevity have become more important than ever, and
facilities need to have a multi-pronged approach to maintaining components. To accomplish
this requires not just a good plan and execution of that plan, but taking advantage of every
single tool available to aid in good, solid, and precise identification of problem areas. One must
also have competent, forward-thinking personnel applying service and maintenance with the
propensity to not only think outside the proverbial box, but take extra steps along the way that
sometimes uncover hidden time bombs. That was certainly the case in this example.
Jerry and Jeff could have easily performed their duties on just the components contained in the
inventory and gone home. In between tasks, the conscientious nature of the technicians shone
through by their taking a listen to nearby items. The ultrasound is a routine service in many
cases, and “going through the motions” with complacency setting in can be common. It was
anything but routine in this example. When one is expecting to hear NOTHING and something
different transpires, it raises your ears very quickly. You cannot take for granted that
equipment that should be silent will always be that way. Anything can take place, and today’s
stresses on systems foster an atmosphere conducive to deficiencies, particularly on equipment
that typically lacks maintenance.
Budget dollars should be spent wisely in all cases to maximize return and service. Escalating
costs of products, services, and commodities have impacted organizations from coast to coast,
causing shifts in planning strategies that typically result in cuts of maintenance budgets. This
looks good on the balance sheet, but the ramifications of such decisions are seldom taken into
consideration.
What is the cost of reduced maintenance frequency or total inaction? Reducing operating costs
and retaining capital is a must for any business to redeem margins, realize planning goals and
remain solvent. The short-term savings can be literally wiped out with the failure of one major
component in the electrical system, leading to expenditures of hundreds or thousands of times
more than was initially saved. The adage of “you never have enough money to do it right the
first time, but always have enough to do it again” certainly comes to mind when a malfunction
or failure occurs.
Planning should include the most critical items that service any facility. This includes not only
contingency plans if something does in fact fail, but a proactive mindset to maintain these
items in the most cost-effective manner and achieve the desired results of equipment service
for many years. Using all the available tools, technology, and test equipment is the first step in
assuring this outcome. Utilizing service organizations that routinely go the extra mile while
servicing items does not hurt the cause either. In closing, expect the unexpected with electrical
equipment. You never know what will be uncovered even with the most mundane of tasks, and
the “pay dirt” realized comes in the form of a lasting relationship for years to come as
customers get “something for nothing.”
ACKNOWLEDGEMENTS
The author wishes to thank UE Systems, Inc. and Advanced Electrical Testing and Preventative Maintenance for
contributions to this article. We also thank our TEGG customers for giving us the chance to perform inspections
during scheduled maintenance agreements with the intent of gathering information for this paper.
Contributors
Jeff Hinton
Jerry Bennett
Mark Goodman
Alan Bandes
Doug Waetjen
Lead Technician - Advanced Electrical Testing and Preventative Maintenance, Canton, OH
Technician - Advanced Electrical Testing and Preventative Maintenance, Canton, OH
UE Systems, Inc.
UE Systems, Inc.
UE Systems, Inc.