Why are transformers used?
Summary
TLDRThis script explains the necessity of step-up and step-down transformers in electrical power transmission. Power stations often produce high voltages like 12,000 volts, but homes require lower voltages, typically between 120 and 240 volts. To minimize energy loss over long distances, the voltage is increased to around 400,000 volts using a step-up transformer. As the power approaches towns, a step-down transformer reduces it to 11,000 volts for local distribution, and further down to 240 volts for home use. The script also touches on the three-wire system in North America that allows for variable home voltages and contrasts it with the simpler two-wire system used in most of the world, which provides higher power to outlets.
Takeaways
- 🔌 Step Up Transformers: Used to increase voltage at the output, which is essential for long-distance transmission of electricity.
- 🔌 Step Down Transformers: Decrease voltage for local distribution and home use, ensuring safety and compatibility with household appliances.
- 🏠 Voltage Requirements: Homes typically require between 120 and 240 volts, contrasting with the much higher voltages produced by power stations.
- ⚡ Energy Loss: High voltage reduces current, which in turn minimizes energy loss due to resistance in the transmission cables.
- 🌐 Transmission Efficiency: Higher voltages allow for more efficient power transmission over long distances with reduced losses.
- 🔢 Ohm's Law Application: The script explains how resistance and current affect energy loss, using Ohm's Law to illustrate the point.
- 🌎 Voltage Variation: North American homes can have 120 or 240 volts due to a three-wire system, while most of the world uses around 230 volts with a simpler two-wire system.
- 🔑 Voltage Flexibility: The three-wire system in North America allows for half or full use of the secondary coil to achieve different voltage levels.
- 💡 Electrical Design: The two-wire system is simpler and can deliver more power to outlets, useful for high-power appliances like water kettles.
- 📚 Previous Content: The speaker references previous videos on residential electrical systems for further learning.
- 📱 Social Media Engagement: The script encourages following on various social media platforms and a website for more engineering content.
Q & A
What is the purpose of a step-up transformer?
-A step-up transformer is used to increase the voltage on the output, which is beneficial for reducing energy loss during transmission over long distances by decreasing the current that needs to flow through the cables.
What is the purpose of a step-down transformer?
-A step-down transformer is used to decrease the voltage on the output to a level suitable for local distribution and residential use, such as reducing it from high transmission voltages to around 240 volts for home use.
Why do we need to decrease the voltage from a power station to our homes?
-The voltage produced by a power station is typically much higher than what is needed for home use. Decreasing the voltage ensures safety and efficiency in power distribution and use.
What is the typical voltage range needed for homes?
-Homes typically require a voltage between 120 and 240 volts, depending on the region and the electrical system in use.
How does increasing voltage with a transformer reduce energy loss in cables?
-By increasing the voltage, the current through the cable is reduced. Since energy loss in a cable is proportional to the square of the current, a higher voltage results in significantly lower energy loss.
Why is a higher voltage used for long-distance power transmission?
-Higher voltages are used for long-distance transmission because they allow for the same amount of power to be transmitted with less current, thus reducing the energy loss due to the cable's resistance.
What is the typical voltage used for long-distance transmission after a step-up transformer?
-The typical voltage used for long-distance transmission after a step-up transformer can be as high as 400,000 volts, which helps in reducing energy losses over long distances.
How does the three-wire system in North America allow for both 120 and 240 volts?
-The three-wire system in North America uses an additional wire connected to the center of the secondary coil of the transformer, allowing the use of half or the full coil to achieve either 120 or 240 volts.
What is the main difference between the electrical systems in North America and most of the rest of the world?
-In North America, a three-wire system is used, which allows for both 120 and 240 volts, while most of the world uses a two-wire system with a standard voltage around 230 volts.
Why is a two-wire system considered simpler and more efficient for power distribution?
-A two-wire system is simpler because it does not require an additional wire for the center tap of the transformer coil. It also allows more power to be delivered to the outlets, making it useful for high-power applications like boiling water quickly.
How does the resistance of a cable affect energy loss during transmission?
-The energy loss in a cable is directly proportional to the resistance of the cable and the square of the current flowing through it. Higher resistance and higher current result in greater energy loss.
Outlines
🔌 Understanding Transformers and Voltage Regulation
This paragraph explains the function of step-up and step-down transformers in electrical power systems. It clarifies why we need to increase voltage at power stations for long-distance transmission to reduce energy loss due to resistance in cables. The script also discusses how step-down transformers are used to decrease the voltage for local distribution and residential use. The importance of reducing current to minimize energy loss is highlighted, with an example calculation showing the efficiency gain at higher voltages. Additionally, the paragraph touches on the three-wire system used in North America to provide either 120 or 240 volts and contrasts it with the simpler two-wire system used in most of the world, which operates at around 230 volts.
Mindmap
Keywords
💡Step Up Transformer
💡Step Down Transformer
💡Voltage
💡Resistance
💡Electrical Current
💡Energy Loss
💡Three Wire System
💡Two Wire System
💡Efficiency
💡Residential Electrical Systems
Highlights
Use of step-up transformers to increase voltage for efficient power transmission.
Step-down transformers reduce voltage for home use, accommodating the required 120 to 240 volts.
Power stations may produce high voltages like 12,000 volts, necessitating transformation for home use.
Resistance in long-distance transmission cables leads to significant energy losses.
Increasing voltage to 400,000 volts minimizes energy loss during transmission.
Local distribution systems use step-down transformers to reduce voltage to 11,000 volts.
Final voltage reduction to 240 volts for home use via step-down transformers.
High voltage transmission reduces current, thereby minimizing energy loss due to cable resistance.
Calculation example demonstrates how high voltage reduces energy loss compared to low voltage transmission.
North American homes use a three-wire system for 120 or 240 volts, utilizing the center tap of the secondary coil.
Most of the world uses a simpler two-wire system for 230 volts, allowing more power to outlets.
Higher voltages are more suitable for appliances like water kettles, facilitating faster heating.
Previous detailed coverage of residential electrical systems in other videos.
Invitation to follow the channel on various social media platforms for more educational content.
Encouragement to watch more videos on the channel for further learning in electrical engineering.
Introduction of the Engineering Mindset website for additional learning resources.
Transcripts
okay so if we use something called a
step up transformer then we can increase
the voltage on the output
if we use a step down transformer then
we can decrease the voltage on the
output but why would we want that well
the power station might be producing 12
000 volts but your home needs between
120 and 240 volts
the power station is probably a long
distance away
so there's going to be a lot of
resistance in the cables resulting in
huge losses of energy on the way
so instead we use a step up transformer
to increase the voltage to around maybe
400 000 volts then as we reach the town
we use a step down transformer to reduce
this back to around 11 000 volts for
local distribution and then we reduce it
again down to around 240 volts for our
homes by increasing the voltage through
a transformer we reduce the current
energy loss in a cable depends on the
electrical current and the resistance of
the cable if this cable has for example
5 ohms of resistance and we try to send
10 kilowatts through it at 240 volts we
would lose about 87
because the current is high but the
voltage is low and so the losses are
huge but if we were to send this at 400
000 volts we'd lose a tiny fraction of
just one percent
because the current is low
so we can transmit power further and
more efficiently at higher voltages
as a side note the reason homes in north
america can have either 120 or 240 volts
is because they use a three wire system
where an additional wire is connected to
the center of the secondary coil
therefore we can use just half of the
coil to get 120 volts
or the full coil to get 240 volts
however most of the world uses around
230 volts and for this they use just a
two wire system which is a much simpler
design and allows more power to the
outlets and this is useful for example
to quickly boil a water kettle by the
way i have covered residential
electrical systems previously in great
detail links down below for that
check out one of these videos to
continue learning about electrical
engineering and i'll catch you there for
the next lesson
don't forget to follow us on facebook
twitter linkedin instagram tik tok as
well as the engineering mindset dot com
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