Q:
Two six pulse converters used for bipolar HVDC transmission system, are rated at 1000 MW, +- 200 kV. Find the rms current rating required for the SCRs.
Answer & Explanation
Answer: C) 1445 A
Explanation: Transmission voltage = 200 + 200 = 400 kV.
I = P/V = 1000 mW/ 400 kV = 2500 A.
As in 3-phase full converter each SCR conducts for 120° for a total period of 360°.
Irms = 2500 x ?(120/360) = 1443.4 A. Nearly about 1445 A as it is a standard current rating.
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