# Commonly used AC voltage levels

AC voltage levels:

0.316V The most common nominal level for consumer audio equipment is -10 dBV, 0.316 volts root mean square (VRMS).

0.7746V The reference voltage for the decibel unloaded (0 dBu) is the voltage required to produce 1 mW of power across a 600 ohms load (approximately 0.7746 VRMS)

1V  The reference voltage for the decibel volt (0 dBV) is 1 VRMS, which is the voltage required to produce 1 milliwatt of power across a 1 kilo-ohm load

1.228V The most common nominal level for professional equipment is 4 dBu. A signal at +4 dBu is equivalent to a sine wave signal with a peak amplitude of approximately 1.737 volts,or any general signal at approximately 1.228 VRMS.

12V A low voltage lighting system usually operates on 12 or 24 volts.

24V A low voltage lighting system usually operates on 12 or 24 volts.

24V Used for controlling relay coils in some automation and control systems.

50V Low Voltage Directive is effective for voltages in range 50 – 1000 volts a.c. or between 75 and 1500V DC

75V Typical telephone line ring voltage is 75 V a.c.(20 or 25 Hz), it could be between 40 and 150 Volts (15-68 Hz)

100V Mains voltage in Japan. Reference voltage level used on electrical power stations measurements (100V = nominal high voltage on line being measured)

110V Mains power in USA, the voltage you expect to get from mains outlet
115V Mains power in USA, the voltage you expect to get from mains outlet
120V Mains power in USA, the output voltage on the distribution transformer

200V If the voltage is less than 200 V, then the human skin is the main contributor to the impedance of the body in the case of a macroshock—the passing of current between two contact points on the skin.

208V The voltage you expect to get between two phases in USA in case our apartment
gets two phase wires from three phase transformer (208/120V)

220V Old European nominal voltage, harmonized to 230V

230V Electricity supplies within the European Union are now nominally 230 V ± 6% at 50 Hz

240V the voltage you expect get between two hots in USA on your hous
240V Old nominal mails voltage used in UK, harmonized to 230V
240V the voltage you get between two hots in USA on the distribution transformer

277V Voltage between phase and neutral on 277/480V three phase system, used in USA for example lighting loads on big buildings

380V Voltage between phases on 220/380V three phase system (old European system)

400V Voltage between phases on 230/400V three phase system (modern European system)

415V Voltage between phases on 240/415V three phase system (old UK system)

450V If the voltage is above 450–600 V, then dielectric breakdown of the skin occurs

480V Voltage between phases in USA in commonly used 3 phase distribution

600V Three phase power voltage

690V Three phase power voltage used in industry for larger electrical motors (Europe)

1000V Isolation test voltage for 130V rated working voltage basic isolation (IEC950)

1000V Low Voltage Directive is effective for voltages in range 50 – 1000 volts a.c. or between 75 and 1500 volts d.c
1000V There phase power voltage used on 1 kV power distribution (in use in Finland)

1500V Isolation test voltage for 230V rated working voltage (IEC950) (basic isolation)

7.2kV Common distribution voltage in USA

10kV Common distribution voltage in Finland

11kV Common distribution voltage in UK, New Zealand and Australia

12.47kV Common distribution voltage in USA

20kV Common distribution voltage in Finland

25kV Electrical trains use 25kV 50Hz power in Finland

33kV Common distribution voltage in UK, New Zealand and Australia

34.5kV Common distribution voltage in USA

110kV Commonly used voltage level on long distance electrical transportation lines

220kV Commonly used voltage level on long distance electrical transportation lines

400kV Commonly used voltage level on long distance electrical transportation lines

1. ###### URD Cablesays:

336.4 Linnet ACSR Cable consists of one or more layers of aluminium wires stranded over a high strength steel core that can be single or multiple strands depending on the requirement.

2. ###### Tomi Engdahlsays:

The dizzying variety of voltages, frequencies and plug configurations reflects the evolutionary history of electrical products around the world.

Why Does the World Harbor So Many Different Voltages, Plugs, and Sockets?
https://spectrum.ieee.org/energy/the-smarter-grid/why-does-the-world-harbor-so-many-different-voltages-plugs-and-sockets

Standardization makes life easier, but it is often impossible to introduce it to systems that have a messy evolutionary history. Electricity supply is a case in point.

Edison’s pioneering 1882 Pearl Street station transmitted direct current at 110 volts, and the same voltage was used when alternating current at 60 hertz took over in American homes. Later the standard was raised a bit to 120 V , and in order to accommodate heavy-duty appliances and electric heating, North American homes can also access 240 V. In contrast, in 1899 Berliner Elektrizitäts-Werke was the first European utility to switch to 220 V and this led eventually to the continent-wide norm of 230 V.

Japan has the lowest voltage (100 V) and the dubious distinction of operating on two frequencies.

Elsewhere, the world is divided between the minority of countries with voltages centered on 120 V (110–130 V and 60 Hz) and the majority using 230 V (220–240 V and 50 Hz). North and Central America and most countries of South America combine single voltages between 110 and 130 V and the frequency of 60 Hz; exceptions

Human beings are fully to blame for creating this dog’s breakfast of 15 plug-and-socket standards

4. ###### Tomi Engdahlsays:

Power Connectors – Overview

Today we’re going to be taking a look at power connectors.

The type of connections we’ll be going over are the IEC and NEMA standard connectors frequently found in data centers, offices, and home usage.

IEC connectors refer to their connections as either an Outlet or an Inlet compared to the standard Male/Female or Plug/Jack.

It also uses a number system, in which the odd numbers are Outlets and the even numbers are Inlets.

For instance, the C5 connector is an outlet and the C6 is the same form factor, but is an Inlet.

C5 and C6 can commonly be found on laptop power supplies, portable projectors, and some desktop computers.

C7 and C8 can commonly be found on battery chargers, power supplies, video game consoles and some A/V equipment. These connectors are available in both a polarized and non-polarized version. The key difference being that the polarized connector will have one side squared off.

C13 and C14 can commonly be found on desktop computers, monitors, amplifiers, and printers.

C15 and C16 can be found on appliances that generate a lot of heat. It has a similar form factor to the C13/14 but with a small notch underneath the ground. They also feature a higher temperature rating, making them ideal for higher draw equipment.

C19 and C20 can be found on high power workstations and servers, power supplies, large network routers and power units.

5. ###### Tomi Engdahlsays:

International Standard IEC 60038, IEC standard voltages, defines a set of standard voltages for use in low voltage and high voltage AC and DC.

The limits are clearly defined, however, in the IEC 60038 standard before 2017: low voltage is up to 1000 V, medium voltage is from 1000 V to 35 kV, and high voltage is over 35 kV.

1000 – 36K was medium voltage before 2017

But the last updated of IEC 60038
The term medium has removed

6. ###### Tomi Engdahlsays:

Reduced Low Voltage – Frequently Asked Question
https://www.blakley.co.uk/sites/default/files/technical_files/TDS10_RLV_FAQs_0.pdf

Q. What is a Reduced Low Voltage (RLV) system?A. Reduced Low Voltage is defined in the Wiring Regulations (BS7671:2008) as “A system in which the nominal line to line voltage does not exceed 110V and the nominal line to earth voltage does not exceed 63.5V”.Q. What are the benefits of an RLV system?A. The significant benefit of this system is the reduced shock risk associated with having a lower voltage between live conductors and earth. On single phase systems the maximum shock risk to earth is 55V and on three phase systems the maximum shock risk to earth is 63.5V. Since the introduction of RLV systems in the 1960s, it is believed that no one has died purely as a result of an electric shock from an RLV supply. This cannot be said of conventional mains-rated systems where the shock risk is 230V.

7. ###### Tomi Engdahlsays:

Voltage in Japan is 100 Volt

The frequency of electric current is 50 to 60 Hertz
The frequency of electric current is 50 Hertz in Eastern Japan (Tokyo, Yokohama and other northern area), 60 Hertz in Western Japan (Nagoya, Osaka, Kyoto, Hiroshima and other southern area)

One of the US plug pins is large and the others are small, and Japanese two pins are the same size as smaller US plug pins. However, many of the Japanese homes have wall outlet that the US plugs can fit.

https://www.furniture-rental-tokyo.com/useful_info/electricity.html

8. ###### Tomi Engdahlsays:

EEVblog 1417 – Alternating Current AC Basics – Part 1

10. ###### Tomi Engdahlsays:

Verkkovirrankin nimellisjännite 230V ja hyväksytty vaihteluväli on 207V – 244V kuormituksestariippuen.

11. ###### Tomi Engdahlsays:

Powering the Smart Revolution at 277 Vac
July 27, 2021 by Ron Stull – 4 Minute Read
https://www.cui.com/blog/powering-the-smart-revolution-at-277-vac

Introduction

Widespread deployments of smart systems in out-of-home locations, as well as high-power applications such as roadside vehicle chargers, is driving easier access to ac-dc power supplies capable of handling a 277 Vac input derived from the standard 480 V three-phase industrial supply.

As consumers we mostly use appliances that are designed to plug into the 120 V ac domestic line, whereas utilities provide services at several voltages for different types of users and applications. Houses and other premises can have access to a 240 V service for large loads, while a 480 V three-phase supply is available for industrial uses. The phases are often used together to supply large loads, typically high-power electric motors used in industrial machinery.

Distributing power at 480 V delivers several advantages. The current is lower, for a given power demand, resulting in lower I2R losses in the line. In addition, cabling can have a lower current rating, saving cost as well as bulk in the distribution infrastructure. At the same time, the higher voltage allows greater capacity to connect more loads on the same line.

Where Does 277 Vac Come From?

Single-phase power can be taken from this 480 V three-phase supply by connecting between one phase and neutral. In this case, the nominal supply voltage is 480 V ÷ √3, or 277 V.

277 Vac Applications

With the adoption of low-energy LED lighting in factories, warehouses, offices, shopping malls, and street lighting, demand grew for constant-current LED drivers (suitable for connection to the 277 Vac supply and for generating a constant-current output for driving the LEDs). Things are changing now that the smart revolution is driving intelligent “things” into out-of-home locations.

As with earlier fluorescent and LED lighting challenges, taking a 277 V single-phase supply from the 480 V three-phase service enables a convenient and cost-effective solution. What’s different with the smart revolution is that many of these loads contain electronics modules that need to be powered from a regulated dc voltage. As a result, demand is growing for ac-dc power supplies that can connect to a 277 Vac input and produce common dc output voltages.

10% Headroom and 305 Vac Rating

To be able to handle a nominal 277 Vac input voltage, with 10 percent safety headroom, the power supply must be capable of withstanding up to 305 V at the input. As a result, you will see a growing number of ac-dc power supplies in the market that offer a universal ac input voltage range from 85 V to 305 V. There is a broad choice of regulated output voltages and various options are available.

Conclusion

Having a versatile selection of 85 ~ 305 V ac-dc power supplies available is useful to designers of IoT and IIoT equipment, installers, maintenance managers and purchasers who can now benefit from changes in the market, allowing them to quickly discover a suitable unit, off the shelf, to meet their exact needs.

12. ###### Tomi Engdahlsays:

Electrical Traction Systems

Track electrification is the type of source supply system used while powering all electric locomotive systems. This can be ac or dc, or even a composite supply.

There are three main forms of electric traction systems:

Direct-current (dc) electrification system
Alternating-current (ac) electrification system
Composite system

Direct current can vary with 300, 500, 600, 750, 1200, 1500, and 3000 V dc.
Alternating current varies with 15 kV ac @16.7 Hz or 25 kV ac @50/60 Hz.
And there’s a composite system with 1.5 kV dc, 3 kV ac @16.7 Hz, or 25 kV ac @ 50 Hz

13. ###### Tomi Engdahlsays:

Hoping for some insight from the pros here..

The output transformer has five taps: 4, 8, 16, 250 and 500 ohms.

My question is what on God’s green earth would the 250 ohm and 500 ohm taps be used for??

This isn’t exactly a test equipment question, so moderators please delete if not appropriate.

If you haven’t been told yet, those 250 and 500 ohm outputs are 25.5 and 70 volt outputs. Professional amps (like the one I used for a production plant paging system) used the 70 volt output. This was done to keep the output from dropping to 0 on long wiring runs. Multiple speakers were wired to it, and each speaker contained a 70 volts down to 16/8/4 ohm transformer. You can’t take a 8 ohm output and hook 30 8 ohm speakers across it. It would be like a direct short. You also couldn’t run 1 8 ohm speaker from the 8 ohm output if it had a 1000′ wire pair run between them. You would have very low or no volume at the speaker end because of voltage drop.

Also, older record lathe cutter heads are often 500 ohm.

PA system for a building. 70vac at rated power, Transformers on individual speakers have taps for various wattages at 70vac on the primary…. add up all the wattage settings on the string to less than or equal to the amps rated power. Japans standard is 100V

14. ###### Tomi Engdahlsays:

• Input voltage 85 to 305VAC including operation at 277VAC

15. ###### Tomi Engdahlsays:

Difference Between VOLTAGES – Why We Need Them All

What is the difference between all of these different voltages? Why are they used, what’s the purpose behind them, and where do the numbers come from?

16. ###### Ryan says:

This is a pretty cool page. I noticed one commonly used transmission line voltage in U.S. that you missed though; 69kV

17. ###### Ryan says:

This is a pretty cool page. I noticed one commonly used transmission line voltage in U.S. that you missed though; 69kV

18. ###### Ryan says:

This is a pretty cool page. I noticed one commonly used transmission line voltage in U.S. that you missed though; 69kV

19. ###### Ryan says:

This is a pretty cool page. I noticed one commonly used transmission line voltage in U.S. that you missed though; 69kV

20. ###### Tomi Engdahlsays:

Mitigate EMI in Your 400-Hz Systems
May 5, 2022
How does 400-Hz EMI affect other electronic systems? This article will help designers to understand and properly filter the 400-Hz frequency component in some electronic systems.
Steve Taranovich
https://www.electronicdesign.com/power-management/whitepaper/21241006/electronic-design-mitigate-emi-in-your-400hz-systems?utm_source=EG+ED+Analog+%26+Power+Source&utm_medium=email&utm_campaign=CPS220505061&o_eid=7211D2691390C9R&rdx.ident%5Bpull%5D=omeda%7C7211D2691390C9R&oly_enc_id=7211D2691390C9R

What you’ll learn:

What led to the 400-Hz generator as the answer for aviation power?
Challenges with EMI filters.
Topology for a 5-kW power supply targeting aircraft applications.

Modern aircraft electrical systems use a variety of ac and dc power voltages/currents. The most common voltage and frequency is 400 V ac @ 400 Hz, 115 V ac @ 400 Hz, and 28 V dc. In this article, we’ll primarily discuss 400-Hz ac and its effect on neighboring electronic systems.

Why Does Aviation Use 400-Hz Power?

When aviation began using electrical systems years ago, the industry chose dc power. When ac later became more prevalent in aircraft, the primary goal was reducing the size and weight of transformers, motors, and power supplies. Designers later opted to use a higher frequency, which would lead to lighter-weight components.

At this higher frequency, more power would be lost in the transmission lines, which would also increase cost. (The two key properties here are dielectric conductance and copper resistance that cause signal loss at high frequency; this is because they vary with frequency.) However, the length of power transmission systems within the aircraft was short, so the power loss became negligent.

Power engineers ultimately designed a unique generator that created the 400-Hz output used today. This allowed an original motor, which was fairly large and heavy, to be replaced by a far smaller and lighter version that could perform the same work. The reduced weight enabled an increase in cargo capacity and trimmed-down fuel consumption.

It was then that power at 400 Hz for aviation became successful and was ultimately used as the standard of modern ac-powered aircraft. Airports worldwide quickly standardized on this 400-Hz power system, which had a cable and plug that enabled the aircraft to land at any area of the globe to receive proper service.
400-Hz EMI Filters

The 400-Hz operating frequency creates a significant challenge for EMI filters. The main drawbacks are high leakage current and increased magnetic core losses, which will lead to heating in both inductors and capacitors. Eventually, this could cause filter failure.

In these 400-Hz applications, designers must be sure that the EMI filter will operate safely. Plenty of existing commercial filter reference designs can operate well at 400 Hz.

How can designers meet the CE101 conducted emissions to meet MIL-STD-461G? This standardhas applications from 30 Hz to 10 kHz for power leads, which also includes power returns. Their power comes from other sources that aren’t part of the Equipment Under Test (EUT) in surface ships, submarines, Army aircraft (including flight line aircraft), and Navy aircraft.

The main difficulty in meeting the standard will be the low frequency content of the noise signals. Usually, the 3rd, 5th, and 7th harmonics will be the problem frequencies. So, for 400 Hz power, designers must be able to attenuate the 1,200-, 2,000-, and 2,800-Hz harmonics.

A 400-Hz Aircraft Power Supply

How does one design a 5-kW power supply for aircraft applications? A boost power-factor-correction topology, the Delta rectifier, will comply with military standards for conducted emissions (CE). The design has a front-end rectifier for a 400-Hz mains power supply. For isolation and output dc voltage regulation, a full-bridge dc-dc converter that has a 99% efficiency, along with a high-frequency transformer, could be designed (see Reference 7).

Summary

Aircraft systems chose a 400-Hz frequency based upon two key parameters: mass and volume. Transformers and rotating machines, running at a higher frequency, led to reduced volume and mass.

21. ###### umar says:

The Main Reason for high voltage Transmission is to amplify the effectivity and maintain it provident. When transmission of Electricity is carried out over lengthy distances, its takes place alongside with voltage drop due to a range of losses upset alongside the path. With the help of High Voltage Transmission, we can limit these losses as nicely as the freights concerned in the captain and accordingly enhance the effectivity of strength transmission and maintain it provident.

22. ###### umar says:

The Main Reason for high voltage Transmission is to amplify the effectivity and maintain it provident. When transmission of Electricity is carried out over lengthy distances, its takes place alongside with voltage drop due to a range of losses upset alongside the path. With the help of High Voltage Transmission, we can limit these losses as nicely as the freights concerned in the captain and accordingly enhance the effectivity of strength transmission and maintain it provident.

23. ###### Tomi Engdahlsays:

For distributed speaker systems 100V and 70V nominal level systems are commobly used

24. ###### Tomi Engdahlsays:

There are 25V, 70V, & 100V Constant Voltage Speaker Systems in use

25. ###### Tomi Engdahlsays:

Geberate 120V AC with amplifier
https://youtu.be/3AYJBUaT74Q

26. ###### Tomi Engdahlsays:

Here is a videos on generating mains power with audio amplifier
https://youtu.be/3AYJBUaT74Q
https://youtu.be/w_0UZviEDhc

27. ###### 15kv cablesays:

11kv 3 core xlpe cable for energy networks where mechanical stresses are expected. Suitable for underground installation or inducts. The cable is suitable for rated voltage 6/10KV according to IEC 60502-2.

28. ###### Tomi Engdahlsays:

Aircraft AC ground power is 115 volts three phase 400 hertz. That’s the nato standard. That and 28VDC.

29. ###### Tomi Engdahlsays:

60Hz/230V is the norm in cruise ships

60hz 220v and quite possibly IT-grounding is pretty much standard.

30. ###### Tomi Engdahlsays:

Which one is better
1 higher voltage low current
2 higher current low voltage

n most cases, option 1, higher voltage, lower current, is preferable. Here’s why:

Power: Power is the product of voltage and current (Power = Voltage x Current). So, for the same amount of power, a higher voltage with a lower current allows for more efficient transmission. This is because higher voltage experiences less energy loss due to resistance in wires.

Safety: High currents can generate more heat in wires and components due to resistance. This can lead to safety hazards and overheating.

Thinner wires: Since lower current is involved, thinner wires can be used for transmission, saving weight and space. This is especially important in applications like airplanes and electronics.

However, there are some situations where option 2, higher current, lower voltage, might be preferable:

Limited voltage tolerance: Some devices might have a limited voltage tolerance. In such cases, a lower voltage with a higher current might be necessary to avoid damaging the equipment.

Short distances: If the transmission distance is very short, the power loss due to resistance might be negligible. In such cases, using a lower voltage and higher current might be simpler or more cost-effective.

Overall, for most general applications, higher voltage and lower current is the better choice due to efficiency, safety, and practicality.

31. ###### Tomi Engdahlsays:

Also voltage affects safety:

Safety: High voltages are more dangerous to touch than low voltages. If you touch high voltage wire, more current can go through you to ground. This can lead to safety hazards. Up to tens of volts are not usually very dangerous, but over hundred volts can easily be lethal.

32. ###### Tomi Engdahlsays:

The International Electrotechnical Commission (IEC) and the UK IET (BS 7671:2008) define an ELV device or circuit as one in which the electrical potential between two conductors or between an electrical conductor and earth (ground) does not exceed 120 volts (V) for ripple-free direct current (DC) or 50 VRMS (root mean square volts) for alternating current (AC).

33. ###### Tomi Engdahlsays:

Mike Metzger
The International Electrotechnical Commission (IEC) and the UK IET (BS 7671:2008) define an ELV device or circuit as one in which the electrical potential between two conductors or between an electrical conductor and earth (ground) does not exceed 120 volts (V) for ripple-free direct current (DC) or 50 VRMS (root mean square volts) for alternating current (AC).
In more arduous conditions, 25 VRMS alternating current or 60 V (ripple-free) DC can be specified to further reduce hazard. Lower voltage can apply in wet or conductive conditions where there is even greater potential for electric shock.
https://en.m.wikipedia.org/wiki/Extra-low_voltage