What to Monitor When Running a Dry-type Transformer

Monitoring has proved vital in efforts to optimise equipment health and performance, and to avoid unscheduled downtime. As a critical part of most industry sectors, transformers can also be monitored to pick up early signs of any issues that might lead to equipment failure.

This is important because transformers usually feed many applications – or loads – in the work environment, all of which will be halted in the case of a catastrophic failure. Also, transformers are purpose-designed for their particular application, so it is unlikely that one will be immediately available to replace the faulty unit. Procuring a replacement with the right specifications will take time, leaving the user stranded for weeks or even months.

With regard to dry-type transformers – which need relatively little maintenance – there are two key operational aspects which can be monitored to avoid such a situation: temperature and voltage.

The temperature of each winding and core must be tracked to pick up higher-than-normal temperatures. These deviations are usually a warning that the transformer is being overloaded, that the air flow to cool the unit could be obstructed, or that ancillary cooling equipment like fans may not be working properly. This will undermine the performance of the transformer and eventually lead to failure.

The internal temperature of the transformer’s enclosure – which keeps out dust and moisture – can also be monitored.

The second key aspect is the voltage, and both the primary and secondary voltage need to be monitored to check for potentially harmful surges. If voltage spikes continue over time and are not mitigated with the use of adequate surge protection, transformer failure is inevitable. When identified in time, though, it is possible to analyse the upstream voltage supply and act accordingly to ensure a stable supply is restored.

Results from monitoring are most effective when they are used to inform a preventative maintenance programme which will avoid unplanned downtime.

The cost of monitoring and preventative maintenance is a fraction of the cost of repairing a unit after a serious failure, especially considering the added impacts of production being disrupted and potential revenue being lost.