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प्रश्न
The 300 turn primary of a transformer has resistance 0.82 Ω and the resistance of its secondary of 1200 turns is 6.2 Ω. Find the voltage across the primary if the power output from the secondary at 1600V is 32 kW. Calculate the power losses in both coils when the transformer efficiency is 80%
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उत्तर
Given data:
NP = 300, NS = 1200, VS = 1600 V, RP = 0.82Ω,
RS = 6.2Ω, PS = 32 KW
1) PS = VSIS
`"I"_"S" = "P"_"S"/"V"_"S"`
`= 32000/1600`
IS = 20 A
2) `"V"_"P"/"V"_"S" = "N"_"P"/"N"_"S"`
`"V"_"P" = 300/1200 xx 1600`
= 400 V
3) η = `"P"_"S"/("V"_"p""I"_"p")`
`= 80/100 = 32000/(400 xx "I"_"p") = 32000/320`
Ip = 100 A
4) Power loss in primary = (IP)2 × RP
= 100 × 1000 × 0.82
= 0.82 × 1000
= 8.2000 = 8.2 KW
5) Power loss in secondary = (IS)2 × RS
= 20 × 20 × 6.2
= 400 × 6.2
= 2480 W = 2.48 KW
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संबंधित प्रश्न
The primary coil of an ideal step-up transformer has 100 turns and the transformation ratio is also 100. The input voltage and power are 220 V and 1100 W, respectively. Calculate the
(a) number of turns in secondary
(b) current in the primary
(c) a voltage across secondary
(d) current in secondary
(e) power in secondary
The teachers of Geeta’s school took the students on a study trip to a power generating station, located nearly 200 km away from the city. The teacher explained that electrical energy is transmitted over such a long distance to their city, in the form of alternating current (ac) raised to a high voltage. At the receiving end in the city, the voltage is reduced to operate the devices. As a result, the power loss is reduced. Geeta listened to the teacher and asked questions about how the ac is converted to a higher or lower voltage.
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Long distance power transmissions
The large-scale transmission and distribution of electrical energy over long distances is done with the use of transformers. The voltage output of the generator is stepped up. It is then transmitted over long distances to an area sub-station near the consumers. There the voltage is stepped down. It is further stepped down at distributing sub-stations and utility poles before a power supply of 240 V reaches our homes.
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