TWO men were treated for burns, after a transformer exploded at Liddell Power Station near Muswellbrook on Thursday afternoon.
The incident occurred just before 3pm while maintenance work was being carried out on the transformer.
A worker who suffered burns to his face and hands was flown in the Westpac Rescue Helicopter to the John Hunter Hospital.
Another worker who suffered minor burns was taken to Singleton hospital.
About 300 employees and contractors were also evacuated from the site.
The cause of the incident is under investigation. Electricity production was not effected.