A 200kva rated transformer has a full load copper loss of 1.5kw and iron loss of 1kw determine the transformer efficiency at full load 0.85 power factor?

First, we need to calculate the total losses in the transformer at full load:

Total losses = Copper loss + Iron loss
Total losses = 1.5 kW + 1 kW
Total losses = 2.5 kW

Next, we need to calculate the output power of the transformer at full load:

Output power = 200 kVA * 0.85
Output power = 170 kW

Now, we can calculate the efficiency of the transformer at full load:

Efficiency = (Output power / (Output power + Total losses)) * 100
Efficiency = (170 kW / (170 kW + 2.5 kW)) * 100
Efficiency = (170 / 172.5) * 100
Efficiency = 0.985 * 100
Efficiency = 98.5%

Therefore, the efficiency of the transformer at full load with a 0.85 power factor is 98.5%.

Given:

- Transformer rating: 200 kVA
- Full load copper loss: 1.5 kW
- Full load iron loss: 1 kW
- Power factor: 0.85

Formula for transformer efficiency:

```
η = (Output power) / (Input power)
```

Calculating output power:

Output power = Transformer rating - Power factor
Output power = 200 kVA - 0.85
Output power = 170 kW

Calculating total losses:

Total losses = Copper loss + Iron loss
Total losses = 1.5 kW + 1 kW
Total losses = 2.5 kW

Calculating input power:

Input power = Output power + Total losses
Input power = 170 kW + 2.5 kW
Input power = 172.5 kW

Calculating efficiency:

```
η = (Output power) / (Input power)
η = 170 kW / 172.5 kW
η = 0.986
```

Therefore, the transformer efficiency at full load 0.85 power factor is 98.6%.