3.1 State how eddy currents may be limited in the iron core of a transformer - NSC Electrical Technology Electronics - Question 3 - 2016 - Paper 1

1. Both transformers serve the same functional operations, such as voltage transformation for electrical energy distribution.
2. Both types are used to step down or step up the supply voltage, maintaining the essential function of transforming electrical energy.

1. Insufficient ventilation which can result in increased ambient temperatures within the transformer.
2. Constant overloading that leads to overheating due to sustained high currents beyond rated capacity.

1. Single-phase and three-phase supply to commercial sites.
2. Three-phase supply to industrial areas.

A transformer plays a crucial role in a distribution network by converting high voltage electrical energy from transmission lines down to a lower, safer voltage suitable for residential and commercial use. This voltage transformation allows for efficient energy delivery over long distances while ensuring the safety and usability of electricity in end-user applications.

The primary phase voltage is given as $V_{ip} = 6.6 \text{kV}$.

To find secondary phase current, use the formula for transforming power: $P = V_{ps} \times I_s \times Cos \theta$. Rearranging gives: $I_s = \frac{P}{V_{ps} \times Cos \theta} = \frac{15 \text{kW}}{230 \text{V} \times 0.8} \approx 81.25 ext{A}.$ However, since $I_s$ is provided as 30 A, it confirms the load's specifications.

The primary power is equal to the apparent power which can be calculated using the formula: $P_{primary} = V_{ip} \times I_{p} \times Cos \theta.$ It can be inferred from the output parameters that $P_{primary}$ should match the output power of 15 kW if calculated under ideal conditions.

The turns ratio (n) can be determined by the voltage ratio: $n = \frac{V_{ip}}{V_{ps}} = \frac{6.6 \text{kV}}{230 \text{V}} = 28.7.$ This implies that the primary has approximately 28.7 times more turns than the secondary.