Answer :
Final answer:
An overcurrent protection device for a buck-boost transformer with a current of nine amperes or more is allowed to be rated at 125% of the full-load current, considering safety margins. The correct option is 4) 125%
Explanation:
When a buck-boost transformer has a current of nine amperes or more, an overcurrent protection device is allowed to be rated at 125% of the full-load current. Considering safety regulations, which typically limit continuous use to 80% of the breaker current capacity, a rating of 125% provides a buffer that accounts for potential short-term overloads without tripping the protection device prematurely.
This allows for the circuit/safety limits to be respected while enabling the transformer to handle temporary peaks in current that might otherwise cause a lower-rated breaker to trip. This is especially important for devices like heating appliances that might draw higher currents intermittently. Thus, adequate protection must be in place to prevent damage due to large currents, while also avoiding undue service interruptions.
When a buck-boost transformer has a current of 9 amperes or more, an overcurrent protection device is allowed to be rated at 125% of the full-load current.
