Video Highlight Logo
VIDEO HIGHLIGHT
Transformers: How They Increase Voltage
SummaryTranscriptChat

Transformers: How They Increase Voltage

How Transformers Work

This section explains the basic functioning of step-up and step-down transformers, highlighting the relationship between voltage, current, and power.

Step-Up Transformer

  • A step-up transformer increases voltage by having more turns of wire on the secondary side.
  • This results in a decrease in current.
  • The purpose of a step-up transformer is to increase voltage while decreasing current.

Step-Down Transformer

  • A step-down transformer decreases voltage by having fewer turns of wire on the secondary side.
  • This leads to an increase in current.
  • The purpose of a step-down transformer is to decrease voltage while increasing current.

Power Transfer and Volt-Amps (VA)

  • In a transformer, power transfer is measured using volt-amperes (VA).
  • The product of voltage and current on each side of the transformer should be equal.
  • This value represents the apparent power or volt-amperes (VA).

KVA vs Kilowatts

  • Transformers use kilovolt-amperes (kVA) instead of kilowatts (kW) because they only transfer power between coils.
  • The actual kilowatt value depends on what is connected to the transformer.
  • Manufacturers state the total rated apparent power in kVA since loads vary in true power and power factor.

Power Factor and Reactive Power

This section discusses power factor, reactive power, and their relationship to true power in AC circuits.

Power Factor

  • Power factor is the ratio of true power (kilowatts) to apparent power (volt-amperes).
  • It represents efficiency or how much useful work is done compared to wasted energy.

Reactive Power

  • Reactive power refers to energy consumed without producing useful work. It is wasted as heat.
  • Reactive power is measured in volt-amperes reactive (VAR).
  • It is represented by the foam in a glass of beer, which is useless and unwanted.

Apparent Power

  • Apparent power is the total volume of the glass, including both beer and foam.
  • It is measured in volt-amperes (VA).
  • The less foam (reactive power) passed through, the more beer (true power) you get for your money.

Transformer Ratings and Load

This section explains how transformer ratings are determined and how they relate to load.

Transformer Ratings

  • Transformer manufacturers state the maximum capacity or size of the transformer.
  • The actual load depends on what is connected to it.
  • Manufacturers provide a rated apparent power in kVA but do not know the specific kilowatt value.

Load Variation

  • AC circuit loads vary based on true power (kilowatts) and power factor (efficiency).
  • Different devices have different power factors, resulting in varying loads on transformers.
  • A good bartender provides more beer (true power) with less foam (reactive power), maximizing efficiency.