🔴 Transformer || One shot Video || All topics || working and construction #polytechnic #transformer

Main Ideas / Lessons Covered (Transformer Syllabus)

The video outlines a study plan for transformers and then teaches each topic in order:

1. Construction
2. Working principle and operation
3. Single-phase vs three-phase transformers (types + comparison)
4. Transformer EMF (voltage) equation derivation
5. Transformer losses
   • Iron/core loss
   • Copper/winding loss
6. Transformer efficiency
   • Definition and formula
   • Condition for maximum efficiency

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Detailed Topic-by-Topic Outline

1) Construction of a Transformer

Two main parts

• Core

  • Made using laminated steel (thin steel sheets stacked together).
  • Purpose: provide a low-reluctance path for magnetic flux so flux doesn’t escape.
  • Why laminated (not solid steel):
    • Solid steel increases heating due to losses such as:
      • Hysteresis loss
      • Eddy current (E.D.) loss
  • Core types mentioned (to be studied later):
    • Shell type
    • Core type

• Windings

  • Two sides of the transformer:
    • Primary side / Primary winding
      • Input supply is connected here.
    • Secondary side / Secondary winding
      • Load is connected here (output is taken here).
  • The primary winding induces effects in the secondary through magnetic flux in the core.

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2) Working Principle and Operation

Working principle: Mutual induction

• When the flux from one coil cuts the other coil, an EMF is induced in the other coil.

Operational description (as explained)

• Apply AC supply to the primary winding.
• Alternating flux is produced in the core.
• The alternating flux cuts the secondary winding repeatedly.
• Due to cutting, EMF is induced in the secondary.
• When a load is connected, the EMF drives current in the secondary.

Voltage change: step-up / step-down idea

• Step-down: reduce secondary turns → secondary voltage decreases.
• Step-up: increase primary turns (as stated in subtitles) → voltage can increase.
• Main idea: transformer changes voltage using turn ratios.

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3) Types of Transformers (Single-Phase vs Three-Phase)

Two main types

• Single-phase transformer
• Three-phase transformer

Comparison points emphasized for exams

• Windings count
  • Single-phase: 1 primary + 1 secondary
  • Three-phase: 3 primary + 3 secondary
• Construction complexity
  • Single-phase: simpler
  • Three-phase: more complete and more difficult
• Typical application
  • Single-phase: smaller purposes
  • Three-phase: larger/bigger applications
• Efficiency
  • Three-phase: efficiency is very good
  • Single-phase: efficiency is comparatively less
• Size
  • Single-phase: smaller
  • Three-phase: bigger
• Cost
  • Single-phase: lower cost
  • Three-phase: higher cost

Working of three-phase (methodological explanation)

• Explained as working “one phase at a time” using the same mutual induction concept.
• Each of the three primary windings produces flux that cuts secondary windings.
• The video suggests that all primaries cut all secondaries.
• Underlying principle remains the same as single-phase, extended to three phases.

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4) Transformer EMF Equation (Derivation Concepts)

Goal

• Derive the relationship for induced EMF in transformer windings using electromagnetic induction.

Key elements used

• AC supply produces sinusoidal variation of flux.
• Flux notation (from subtitles): flux is shown as something like Φ, relating to maximum flux with a sinusoidal term involving ωt.
• Faraday/Lenz-law style induction:
  • EMF is expressed using the change of flux with time.

EMF expression structure (as described)

• e = n × (dΦ/dt) (sign indicated by Lenz’s law as negative)

Phase relationship mentioned

• Induced EMF lags by 90° relative to flux (as stated).

RMS / “EMF equation” outcome (important exam step)

• The video states you find maximum EMF first, then convert to RMS.
• A common transformer constant result is used:
  • 4.44

Final idea conveyed

• Compute primary and secondary EMFs similarly using:
  • turns (N), frequency (f), maximum flux term (often written via Bm/maximum flux density), and core-related constants.
• The subtitles do not clearly present final clean formulas, but they emphasize the method and the role of 4.44.

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5) Losses of a Transformer

Two types of losses

1. Iron loss (Core loss)
2. Copper loss (Winding loss)

Iron/Core loss

• Occurs in the core.
• Caused by alternating flux due to AC supply.
• Includes two components:
  • Hysteresis loss
  • Eddy current (E.D.) loss
• Treated as constant loss (in simplified teaching): approximately the same over life, not dependent on load level.
• Determined via open-circuit test.
• Depends on:
  • maximum flux density
  • frequency

Copper/Winding loss

• Occurs in the windings (primary and secondary).
• Caused by ohmic resistance of the windings.
• Treated as variable loss:
  • depends on load current
  • follows approximately ∝ I² (the I²R idea)
• Determined via short-circuit test.

Total transformer loss

• Total loss = Iron loss + Copper loss

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6) Efficiency of a Transformer

Definition

• Efficiency = Output power / Input power

Formula form described

• Input power = Output power + Losses

Full-load efficiency setup

• Output power expressed as:
  • Pout = V2 I2 cosφ2 (as described via secondary side)
• Losses included:
  • Iron loss (constant) (often labeled like Pi)
  • Copper loss (variable) using current and resistance; follows I²R

Maximum efficiency (method + condition)

• The video performs the logic:
  • Start from efficiency at full load
  • Differentiate efficiency w.r.t. load/current
  • Set derivative = 0 to find the maximum condition
• Key result stated:
  • Maximum efficiency occurs when:
    • Iron loss = Copper loss
• Exam takeaway:
  • Condition for maximum efficiency:
    • Piron = Pcopper

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Speakers / Sources Featured

• No specific individual speaker name is provided in the subtitles.
• Source appears to be an unnamed YouTube creator/channel (generic references like “friends,” “like and subscribe”).
• Background audio: [Music] (no named artist/source).

Speakers list

• Unnamed narrator/teacher (main source of subtitles)
• No other identifiable speakers