Power-limited circuits (Class 1) must have a power supply that is not more than what values?

Power-limited circuits (Class 1) must have a power supply that is not more than what values?

• A. 12V and 500VA
• B. 30V and 1000VA
• C. 48V and 2000VA
• D. 60V and 100VA

Answer: (B)

Power-limited Class 1 circuits are defined by two safety limits on the supply: the voltage must not exceed 30 V, and the apparent power must not exceed 1000 VA. Keeping both bounds ensures that the energy available in the event of a fault is low, reducing shock and heating hazards. This means the supply cannot deliver more than 1000 VA, and at the maximum voltage of 30 V that corresponds to about 33 A of current. Any option that goes above 30 V would violate the voltage cap, so the pair that represents the upper bounds for this class is 30 V and 1000 VA. Options with higher voltages exceed the limit, while others do not reflect the maximum allowable values.

Power-limited Class 1 circuits are defined by two safety limits on the supply: the voltage must not exceed 30 V, and the apparent power must not exceed 1000 VA. Keeping both bounds ensures that the energy available in the event of a fault is low, reducing shock and heating hazards. This means the supply cannot deliver more than 1000 VA, and at the maximum voltage of 30 V that corresponds to about 33 A of current. Any option that goes above 30 V would violate the voltage cap, so the pair that represents the upper bounds for this class is 30 V and 1000 VA. Options with higher voltages exceed the limit, while others do not reflect the maximum allowable values.