Transformers with power ratings of 500 KVA and above usually rank very high in the Risk Priority Number tables. With their high cost of replacement, long lead times of typically 12 weeks or more, high in/out swap costs and with many modes of failure impossible to repair onsite, transformers can become a weak link for reliability in your electrical distribution system.
While an electrical distribution system that has been designed for redundancy, such as Main-Tie-Main configurations with each transformer loaded at less than 50% of nameplate capacity, can alleviate the impact of a failure, this is not the only consideration. Large amounts of fault energy are available making some failure modes potentially hazardous to personnel and many transformers are oil filled making flammability and environmental impacts additional considerations. It is much better to come up with ways to detect problems and prevent failures in the first place. A transformer failure can easily add up to tens of thousands of dollars in repair and downtime costs.
Fortunately, there are many types of Condition Based Maintenance (CBM) technologies that can be employed to attempt to catch the early warning signs of
impending failure on transformers.