**Calculation of Actual Resistance and Reactance Referred to HV Side**

Given data:
- Transformer rating: 4 kVA
- Primary voltage (LV side): 400 V
- Secondary voltage (HV side): 200 V
- Resistance (LV side): 0.02 pu
- Reactance (LV side): 0.06 pu

To calculate the actual resistance and reactance referred to the HV side, we need to consider the transformer's turns ratio.

**Turns Ratio Calculation:**

The turns ratio (K) is determined by the voltage ratio:

K = Vh / Vl

Where:
- K: turns ratio
- Vh: HV side voltage
- Vl: LV side voltage

Given:
- Vh = 200 V
- Vl = 400 V

Substituting the values, we get:

K = 200 / 400 = 0.5

**Resistance Referred to HV Side:**

The resistance referred to the HV side can be calculated using the turns ratio:

Rhv = Rlv / K^2

Where:
- Rhv: resistance referred to HV side
- Rlv: resistance on LV side
- K: turns ratio

Given:
- Rlv = 0.02 pu
- K = 0.5

Substituting the values, we get:

Rhv = 0.02 / (0.5^2) = 0.02 / 0.25 = 0.08 pu

Therefore, the actual resistance referred to the HV side is 0.08 pu.

**Reactance Referred to HV Side:**

The reactance referred to the HV side can also be calculated using the turns ratio:

Xhv = Xlv / K^2

Where:
- Xhv: reactance referred to HV side
- Xlv: reactance on LV side
- K: turns ratio

Given:
- Xlv = 0.06 pu
- K = 0.5

Substituting the values, we get:

Xhv = 0.06 / (0.5^2) = 0.06 / 0.25 = 0.24 pu

Therefore, the actual reactance referred to the HV side is 0.24 pu.

**Summary:**

- The actual resistance referred to the HV side is 0.08 pu.
- The actual reactance referred to the HV side is 0.24 pu.

These values are obtained by using the turns ratio to convert the resistance and reactance from the LV side to the HV side. This calculation is necessary to determine the actual values of resistance and reactance on the HV side of the transformer.