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The fluorescent lamp with 40W power and 0.5 power factor is connected to the 220 V / 50 Hz power supply, in which the current is (b) A、0.18A B、0.36A C、0.72A D、0.09A 09A, but the answer is B,
The fluorescent lamp with 40W power and 0.5 power factor is connected to the 220 V / 50 Hz power supply, in which the current is (b)
A、0.18A B、0.36A C、0.72A D、0.09A
Power P = voltage V * current a * power factor
Current = 40 / (220 * 0.5) = 4 / 11A
Choose B
There are single-phase 200V lighting circuit, one is connected with 10 40W fluorescent lamps with power factor of 0.5, and the other is connected with 10 40W incandescent lamps
What is the current of each branch of fluorescent lamp and incandescent lamp? What is the total current in the circuit? What is the total switch and fuse of the selection circuit?
The load factor of incandescent lamp is 0.8, the power factor is 1ke = 10 * 40 * 0.8 = 0.32kws = 0.32/1 = 0.32kva, the current is I = 0.32/0.2kv = 1.6A, the load factor of fluorescent lamp is 0.8, the power factor is 0.5 (you can't find it on the table) k = 10 * 40 * 0.8 = 0.32kws = 0.32/0.5 = 0.64kva, the current is I = 0.64/0.2kv = 3
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