Question

A single-phase transformer has a nominal voltage ratio of 25000/5000 V and it has the following parameter values. R₁ = 100, X₁ = 220; R₂ = 4,X₂ = 10; Rm​ = 200000, Xm​ = 100 100 (Both Rm​ and Xm​ are referred to the HV winding.) where all values are in ohms at the rated frequency of 60 Hz. The rating of the transformer is 100kVA. If the transformer delivers 100kVA at 5000 V when the power factor is 0.8 (lagging), determine

1. the primary voltage required,
2. the voltage regulation,
3. the losses including core losses, and
4. the primary current.

Answer 1

The primary voltage required is -10000 V.

Step-by-step explanation:

To determine the primary voltage required, we can use the formula:

Vp = Vs x (NR2 - NR1) / NR1

Where Vp is the primary voltage, Vs is the secondary voltage, NR1 is the number of turns in the primary winding, and NR2 is the number of turns in the secondary winding.

Plugging in the values, we have:

Vp = 5000 x (10000 - 25000) / 25000 = -10000 V

Therefore, the primary voltage required is -10000 V.