With reference to Transformers, which of the following measures improve energy efficiency?1.Replacing old aluminum-wound transformers with copper-wound transformers.2.Using Amorphous Core transformers to reduce no-load (iron) losses.3.Operating transformers at 90-100% of their rated capacity for maximum efficiency.Select the correct answer using the codes given below:

Correct Answer: C - 1 and 2 only

Quick Concept Explanation

An ideal transformer conserves apparent power and relates voltages, turns and currents inversely. Real transformers additionally have core and copper losses. Key relation: V1/V2=N1/N2=a; I1/I2=N2/N1=1/a; ideal V1I1=V2I2.

Exam focus: Voltage ratio follows turns ratio; current ratio is inverse. Common trap: In an ideal transformer input power equals output power.

Statement-wise Verification

• Statement 1 - Correct.
  Replacing old aluminum-wound transformers with copper-wound transformers.
  Real transformers additionally have core and copper losses.
• Statement 2 - Correct.
  Using Amorphous Core transformers to reduce no-load (iron) losses.
  Real transformers additionally have core and copper losses.
• Statement 3 - Incorrect.
  Operating transformers at 90-100% of their rated capacity for maximum efficiency.
  Maximum efficiency occurs at the load where copper loss equals core loss, not universally at 90–100% rating

Core Concept

An ideal transformer conserves apparent power and relates voltages, turns and currents inversely. Real transformers additionally have core and copper losses. Open-circuit and short-circuit tests separate these loss components without loading the transformer at full power.

Formula / Key Relationship

V1/V2=N1/N2=a; I1/I2=N2/N1=1/a; ideal V1I1=V2I2.

Why the Other Options Are Wrong

Option A is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 2. Option B is incorrect because it includes incorrect statement(s) 3 and omits correct statement(s) 1. Option D is incorrect because it includes incorrect statement(s) 3.

Exam Shortcut / Approach

Voltage ratio follows turns ratio; current ratio is inverse.

Common Mistake

In an ideal transformer input power equals output power.

Quick Revision

Copper Windings and Amorphous Cores is linked with Efficient Transformers, Electrical Energy Efficiency and Energy Management. Voltage ratio follows turns ratio; current ratio is inverse.