Transformer inspections

Inspection of high-voltage equipment is required by the Danish high-voltage regulations. All high-voltage installations must be inspected periodically by an approved operator.

What most often stops HV equipment?

• Rodents: mice and rats
• Poor cable connections
• Worn circuit breakers that malfunction

Periodic inspections reduce the risk of rodent damage and poor connections. The photos show how problems can be found and fixed before they cause downtime.

Rats, mice and thermal imaging

Rats and mice can get into the transformer station if the foundation is not sealed, and can cause short circuits. During our inspections we repair holes in the foundation and transformer housing. Here, new concrete has been laid around the cable entries because rats had undermined the old concrete.

We also use thermal imaging on cable joints, breakers and fuses so poor connections are found in time. Service staff cannot re-tighten these connections without us disconnecting the HV installation. The two thermal images show the cable connections on the turbine’s main breaker, with a slightly poor connection on one phase.