SIB 11

True/False

In a majority of our distributing stations differential bus protection is not provided for the distribution buses.
True False

An unexpected overload of limited duration caused by some unforeseen disturbance of normal operation

150% of full load (50% overload) may be safely carried approximately                  and that 200% of
full load (100% overlaid) may be safely carried approximately     
                , following full load in both instances.

What is the limiting factor in short-time overloading of a transformer

Overloading 
60sec
5min
30min
2hr

True/False

Top oil temperature will usually accurately reflect the 
winding or hot spot temperature after two hours of load. If transformer top oil temperature 
exceeds 80° C for a self cooled transformer or 65° C for a water cooled transformer advise the Area 
Supervisor or Chief Operator and secure managements advice on procedure
True False