Page 6 - EngineerIT September 2022

COVER STORY

Understanding the reason for

transformer failures and guides

to preventing them

rmCoil has a recognized distribution and power An inside look at the typical process is as follows,
transformer repair facility in Roodepoort, accredited but not limited to:
Aby three ISO certifications. Many failures have been • External visual observations by an expert, searching for signs such
incorrectly diagnosed by many clients and remedied with as overheating which can be seen by differences in the paint colour,
limited protection and prevention equipment. This is not cracked or lifted painted areas, faulty or damaged temperature
uncommon as these failures are almost 100% unexpected, control devices such OTI’s (oil temperature indicators) and WTI’s
when in fact they could have all been mitigated through (winding temperature indicators). These devices can be checked for
effective maintenance and risk assessment methods which correct temperature settings and trips and if they are still in a working
have been on the SA market for decades. condition, by means of electrical testing. PRVs (pressure relief valves)
So yes, the end users are 100% responsible for these are investigated for visual evidence of operation; these devices can
failures as they have not managed their assets effectively also be tested to confirm correct settings and whether the device is still
while in operation. But there also many incidents which go in working condition. There are other protection devices on the asset
unnoticed to end-users outside of their control – this is an depending on the manufacturer’s specification and application.
area where ArmCoil can assist in exact Root Cause of Failure After the visual inspection is completed the dismantling process starts so
on all transformers no matter which brand and application. that if required, all the auxiliary protection can be evaluated and tested.
ArmCoil can also assist on the repairs, upgrade and • In the event of the asset being oil cooled, an oil sample for full
remanufacturing of these assets. spectrum oil analysis is taken and sent to a SANAS approved
laboratory for testing and review. The oil sampling provides an
Root Cause Analysis accurate condition of the oil during operation and if the end user’s
By contacting sales@armcoil.co.za we can assist in preferred laboratory has been identified, typically the laboratory will
determining the exact cause of failure on your assets. have a history of all the sampling results in their archives using the
ArmCoil sales & technical team understands the urgency of client, brand and serial number as a point of reference which could be
replacing the unit or the reinstatement of the failed asset invaluable in assisting the RCA.
due to premature/unexpected failures, hence the RCA • In the event of oil cooled on load tap changers, oil samples are taken
(root cause analysis) is incorporated as part of assessment and if historically sampled, these results are still available for review
process. This service is most successful off-site; it may if requested by using the client, brand and serial number too. Tap
also be completed on-site. The sequence of events can be changer condition is also visually inspected and tested for condition or
identified and detailed in a technical written report for client failure analysis. A like process is done in the event of vacuum type tap
review. changers too.

EngineerIT | September 2022 | 4