Question

The efficiency of 400/200 V, 200 kVA transformer is 98.5 per cent at full load at 0.8 lagging power factor. At half load, 0.8 power factor lagging the efficiency is 97.5 per cent. Calculate the values of core loss and full-load copper loss.​

Answer 1

Answer:

no copper loss is the correct answer

Answer 2

Answer:

the core loss = 1923w and the copper loss = 507w

Explanation:

• let, $W_{c}$  will be the core loss and  $W_{cu}$  will be thr copper loss

             by using the bsic formula,

      $n_{f}$ = $= V_{transformer}$ x $lpf$$/$ $V_{transformer}$ x $lpfr +W_{c} +W_{cu}$

            { $lpf= lagging power factor$$}$}

 

                          $0.985$ $= 160$ $/ 160+W_{c} +W_{cu}$

                ∴ $W_{c} + W_{cu}$ $= 2.43kw\\=2430w$---eqno:1

• At half load, $W_{c}$ will remain same but $W_{cu}$ will be one fourth its full load value. Therefore efficiency at half load is,

                            $n_{f} = 100$ x $0.8$ $/ 100$ × $0.8$ $+ Wc + Wcu/4$

                         $0.975 =320/320+4Wc+Wcu$

                         $4Wc +Wcu =8.2kw\\ =8200w$-------eqno:2

• from eq 1&2 we now have the values,

          the core loss = 1923w

                            Wc= 1923w

• the copper loss = 507w

                             Wcu=507w