Transformers must be immediately taken out of operation under the following circumstances:

(1) Unusual and loud internal noises, such as cracking or explosive sounds;

(2) Abnormal and continuously rising temperature of the transformer's top oil under normal load and cooling;

(3) Oil spraying from the conservator or explosion vent;

(4) Severe oil leakage causing the oil level to fall below the indicator limit on the oil gauge;

(5) Excessive discoloration of the oil or the presence of carbonaceous substances in the oil;

(6) Serious damage or discharge phenomena in the bushings;

(7) Occurrence of a personal accident within the transformer's operational area requiring a power outage;

(8) Fire in the transformer;

(9) Reddening, melting, or breaking of the bushing connections and leads.