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nooooooooooooooo412
02.11.2019 •
Physics
50. a large power plant generates electricity at 12.0 kv. its old transformer once converted the voltage to 335 kv. the secondary of this transformer is being replaced so that its output can be 750 kv for more efficient cross‐country transmission on upgraded transmission lines. (a) what is the ratio of turns in the new secondary compared with the old secondary? (b) what is the ratio of new current output to old output (at 335 kv) for the same power? (c) if the upgraded transmission lines have the same resistance, what is the ratio of new line power loss to old?
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Ответ:
Explanation:
a ) The transformer steps up the voltage from 12000 V to 335000 V . Voltage in primary is 12000 V and in the secondary it is 335000 V in old transformer
If n₁ be no of turns in primary coil and n₂ be no of turns in secondary coils
the formula is
n₂ / n₁ = voltage in secondry / voltage in primary
n₂ / n₁ = 335000 / 12000
ratio of turns in old transformer
= 27.9
ratio of turns in new transformer
n₃ / n₁ = 750 / 12 ( n₃ is no of turns in the secondary of new transformer )
= 62.5
T he ratio of turns in the new secondary compared with the old secondary
n₃ / n₂ = 62.5 / 27.9
= 2.24
b ) Current in secondary / current in primary
= turns in primary / turns in secondary
current output ratio of old
= Current in secondary / current in primary
= n₁ / n₂
= 12 / 335
= .03582
current output ratio of new
= Current in secondary / current in primary
= n₁ / n₃
= 12 / 750
= .016
The ratio of new current output to old output (at 335 kV) for the same power
= .016 / .03582
= .4466
c ) power loss in new
= (current in secondary )² x resistance of secondary
=( .016 x current in primary )² x R
= 2.56 X 10⁻⁴ X ( current in primary )² x R
power loss in old
= (current in secondary )² x resistance of secondary
=( .03582 x current in primary )² x R
= 12.83 X 10⁻⁴ X ( current in primary )² x R
ratio of new line power loss to old
= 2.56 / 12.83
= .199
Ответ: