3.1 What is the purpose of a transformer? 3.2 Name the type of loss that is dissipated in a transformer due to the internal resistance in the windings - NSC Electrical Technology Power Systems - Question 3 - 2017 - Paper 1

The type of loss that is dissipated in a transformer due to the internal resistance in the windings is referred to as copper losses, which can be mathematically expressed as $I^2R$ losses.

1. Air cooling
2. Oil-filled self-cooling and oil-filled water cooling.

If cooling methods fail, the transformer can overheat, which may lead to damage to the insulation between the windings. This overheating can cause a short circuit and potentially lead to gas formation, which is highly combustible.

1. Used to distribute power to consumers in substations.
2. To step down the voltage to a 380 V three-phase and 220 V single-phase supply.

To determine the secondary line current ($I_L$):

I_L = rac{S}{ ext{(sqrt(3) * V_{LS}})}

Calculating:

The secondary phase current ($I_{ph}$) is equal to the line current for a delta connection:

$I_{ph} = I_L = 182.32 A$

To find the input power ($P$):

$P = ext{(sqrt(3) * V_{LS} * I_L * ext{p.f})}$

Calculating:

The secondary winding of a step-down transformer has a thicker wire to accommodate a higher current. Since the power in a transformer remains constant (ignoring losses), a decrease in voltage in the secondary winding results in an increase in current, necessitating thicker wires to handle this increased current without overheating.