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Q81HardRectifiers & Converters

એક સિંગલ-ફેઝ ફુલ કન્વર્ટર 230 V, 50 Hz સાથે જોડાયેલ છે. લોડ R = 10 Ω સાથે ખૂબ મોટું પ્રેરકત્વ છે. α = 30° માટે ચકાસો.
1. સરેરાશ આઉટપુટ વોલ્ટેજ આશરે 179.3 V છે.
2. ઇનપુટ પ્રવાહનું RMS મૂલ્ય 17.93 A છે.
3. મૂળભૂત પાવર ફેક્ટર 0.866 છે.
કયાં વિધાનો સાચાં છે?

જવાબ અને પગલાવાર ઉકેલ
સાચો જવાબ: C. 1, 2 અને 3
ટૂંકી સમજૂતી

C — 1, 2 અને 3. Vdc = (2√2×230/π)cos30° ≈ 179.3 V; મોટા પ્રેરકત્વથી Id ≈ 17.93 A અને સ્ક્વેર-વેવ ઇનપુટ પ્રવાહનું RMS = Id = 17.93 A; મૂળભૂત વિસ્થાપન ગુણાંક = cos30° = 0.866.

વિગતવાર ઉકેલ (મૂળ ભાષામાં)

Statement-wise Verification

  • Statement 1 - Correct.
    Average output voltage is approximately 179.3 V.
    Vdc=(2√2×230/π)cos30°≈179.3 V.
  • Statement 2 - Correct.
    The RMS value of the input current is 17.93 A.
    With R=10 Ω and highly inductive continuous current, Id≈17.93 A.
  • Statement 3 - Correct.
    The fundamental power factor is 0.866.
    The fundamental displacement factor is cos30°≈0.866.

Core Concept

A fully controlled bridge feeding a highly inductive load operates with nearly continuous DC current. Firing angle controls average DC voltage; the AC-side current is non-sinusoidal and its fundamental is displaced approximately by α. In three-phase bridges each thyristor conducts for 120 electrical degrees under continuous current.

Formula / Key Relationship

1φ: Vdc=(2Vm/π)cosα≈0.9Vrms cosα; 3φ: Vdc≈1.35V_LL cosα.

Step-by-Step Check

Vdc=(2√2×230/π)cos30°≈179.3 V. With R=10 Ω and highly inductive continuous current, Id≈17.93 A. The fundamental displacement factor is cos30°≈0.866.

Why the Other Options Are Wrong

Option A is incorrect because it omits correct statement(s) 3. Option B is incorrect because it omits correct statement(s) 1. Option D is incorrect because it omits correct statement(s) 2.

Exam Shortcut / Approach

Large load inductance → nearly constant DC current.

Common Mistake

Distinguish displacement factor cosα from total power factor including distortion.

Quick Revision

Average Output and Input Current is linked with Single-Phase Full Converter, Controlled Rectifiers and Power Electronics. Large load inductance → nearly constant DC current.

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