Question

3 similar coils each having a resistance of 15 ohm and an inductance of 0.04 h are connected in star to a 3 phase 50 hz supply, 200 v between lines. calculate the line current. if they are now connected in delta, calculate the phase current, line current and the total power absorbed in each phase.

Answer 1

answer

200 v

explain

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Answer 2

Answer:

• The phase current-$4.17A$
• Line current-$4.17A$
• Total power absorbed in each phase- $27.13 K W$

Explanation:

In a three-phase circuit, there are two types of connections: star and delta. A 4 – wire system is a Star Connection, while a 3 – wire system is a Delta Connection.

Step-1-

Inductive reactance-  $X_{L}=2 \pi f L$

$2 \pi \times 50 \times 40 \times 10^{-3}=12.56\Omega$

Phase impedance- $Z_{p h}=\sqrt{R^{2}+X_{L}^{2}}$

$\sqrt{15^{2}+12.56^{2}}$ = $27.56$

Line voltage - $V_{\text {line }}=\sqrt{3} V_{p h}$ = $V_{p h}=\frac{V_{\text {line }}}{\sqrt{3}}$

$\frac{200}{\sqrt{3}}=115V$

Phase current and line current - $I_{p h}=\frac{V_{p h}}{Z_{p h}}$ = $4.17A$

$I_{\text {line }}=I_{p h}=4.17\mathrm{~A}$

Step-2

If they connected in  delta connection

$Z_{p h}=19.56$

$I_{p h}=\frac{V_{p h}}{Z_{p h}}$  = $\frac{200}{19.56}= 10.22A$

Dissipated power-

$P=\sqrt{3} I_{p h}^{2} R$

$P=\sqrt{3} \times 10.22^{2} \times 15= 27.13KW}$