Answer :
Final answer:
It is permitted to use the next higher standard fuse rating when the calculated fuse rating does not match a standard rating, as safety devices like fuses are designed to accommodate temporary surges in current.
Explanation:
When the current in a buck-boost transformer is more than nine amperes and the calculated fuse rating does not correspond to a standard fuse rating, it is indeed permitted to use the next higher standard fuse rating.
This is based on electrical safety practices that allow for some flexibility in fuse selection to ensure protection while also not impeding the normal operation of electrical devices. Fuses and circuit breakers are safety devices designed to protect circuits from overcurrent, which could cause damage or fire.
Since many electrical appliances have inrush currents that are higher than their steady-state operating currents, fuses and circuit breakers are built to tolerate these higher currents temporarily.
For example, electric motors may draw a high current for a few seconds when they start up, so special 'slow blow' fuses are used in these cases. These slow blow fuses are designed to withstand temporary surges without blowing.
