Lubezine Volume 8 * NOVEMBER 2013 - JANUARY 2014 | Page 23

Fresh trends in grease
manufacturing processes
dictated by insurance requirements, which
often stipulate that annual transformer oil
analysis must be conducted to ensure continued coverage.

PCB analysis
PCBs (polychlorinated biphenyls) are a group
of synthetic oil-like chemicals of the organochlorine family. Until their toxic nature was
recognized and their use was banned in the
early 1980s, they were widely used as insulation in electrical equipment, particularly
transformers. Three types of PCB are normally
used in electrical transformers: Aroclor 1242,
1254 and 1260 and commonly known by
various brand names. These include Askarel,
Chlorectol, Elemex, Inerteen, and Pyranol.
One of the most important problems with
PCBs is that they concentrate in the fatty parts
of microorganisms. This concentration factor
between the organism and the water can be
as much as a million times. Concentrations
are further amplified, as the microorganisms
become food for animals further up the food
chain. PCBs are very stable and their degradation process is slow, making for yet greater
amplification in organisms. Although not
overly toxic in themselves, PCBs are poisons,
which have been shown to cause damage to
the reproductive, neurological and immune
systems of wildlife and humans.
Far more serious are the risks of a fire or an
explosion. At temperatures around 500ºC,
extremely toxic compounds - polychlorinated
dibenzofuranes (PCDF) and polychlorinated
dibenzodioxins (PCDD) - are formed. Small
amounts of these compounds have been
found at accidents where transformers and
capacitors have been exposed to fire or have
exploded. Even if the amounts have been
extremely small and have caused no personal
injuries, it has been necessary to perform very
extensive and costly decontamination work.
PCDDs and PCDFs cause damage and death
in doses as low as 1ppb to 5000ppb. Damage to
organs such as liver, kidney and digestive tract,
miscarriage, sterility can occur, and are some
of the most potent cancer promoters known.

however, these tests are susceptible to false
positive results, since the test does not detect
PCB itself.
Specific methods utilise some type of chromatography to separate PCB molecules from
each other and interfering compounds. It is
not a case of simply finding an easily quantifiable compound, but of quantifying a complex
mixture of compounds. Of the three major
chromatography types, gas chromatography
(GC), thin layer chromatography (TLC) and
liquid chromatography, GC is the preferred
and most extensively-used method.

PCB terminology
Any fluid, including that in electrical equipment and any item, which has a measurable
PCB concentration of less than 50ppm of
PCB, is considered a non-PCB item. Any fluid,
including that in electrical equipment, and any
item which has a measurable PCB concentration of 50ppm or greater but less than 500ppm
is regarded as being PCB contaminated. Additionally, any fluid, including that in electrical

WearCheck in brief
Condition monitoring specialists
WearCheck offer a range of preventive
maintenance solutions, including oil and
fuel analysis, and a host of Reliability
Solutions services, including thermography, vibration analysis, balancing and
alignment.
Based in South Africa since 1974,
WearCheck’s expansive network now
includes ten laboratories spanning
the continent and beyond, including
Johannesburg, Durban, Mpumalanga
Province, and international laboratories
in India, Dubai, Ghana, Mozambique
and Zambia - at Lumwana mine and
Kitwe - with a presence in Cape Town,
Rustenburg, Steelpoort, Port Elizabeth,
Zimbabwe and Namibia.
www.wearcheck.co.za

See story

P.22

equipment and in any item, which has a measurable PCB concentration equal to or greater
than 500ppm, is regarded as a PCB item. It is
important to note that transformer oil that
has not been tested must be classified as PCB
contaminated until shown to be otherwise.
Once the PCB status is determined, a sticker
is issued and fixed to the item in question. This
allows for quick reference and ensures that
potential cross-contamination is avoided
during future sampling, maintenance and
decommissioning if necessary. Blending PCB
contaminated oil with virgin or other oil to
meet the legal requirements is obviously an
illegal practice that has been shown to happen
from time to time. This practice simply has the
effect of contaminating virgin oil supplies and
ensures that the PCBs persist in the environment and leads to further contamination.

Proper transformer sampling.
Just like machinery oil analysis, the ability of transformer oil analysis to provide an
early warning sign of a problem condition
is dependent on the quality of the oil sample
that is sent to the lab. A sampling point on any
equipment should be identified and clearly
labelled for the technician.
As with sampling locations in other types of
equipment, the same location should be used
each time a sample is collected to ensure representative conditions are tested. This point
should be located in a place where a live oil
sample can be collected rather than in an area
where the oil is static.
Just like machinery oil analysis, electrical
transformer oil analysis can play a vital role in
preventing unscheduled outages in electrical
transmission and distribution equipment by
determining the condition