What is the rated voltage

nominal voltage

The nominal voltage of an electrical consumer or a voltage source (battery, generator, power grid) is the value of the electrical voltage specified by the manufacturer or supplier in normal operation. The specification of the nominal voltage is usually supplemented with a tolerance range that is maximum permissible and is specified as the rated voltage in more recent standards.

Nominal voltage of batteries

For batteries and accumulators, the nominal voltage is a suitable, approximate value of the voltage to identify a cell, a battery or an electrochemical system (according to DIN EN 60050-482). The open circuit voltage is always higher than the nominal or rated voltage. The nominal voltage of a battery results from the number of cells connected in series.

The nominal voltage per cell of batteries (non-rechargeable) and accumulators (rechargeable) is:

  • 1.2 V for the nickel-cadmium cell (see nickel-cadmium battery), the nickel-metal-hydride cell (see nickel-metal-hydride battery) and the nickel-iron cell (see nickel-iron -Battery pack)
  • 1.35 V for the mercury oxide-zinc cell, see mercury oxide-zinc battery
  • 1.5 V for the alkaline manganese cell, see alkaline manganese battery
  • 1.5 V for the zinc-carbon cell, see zinc-manganese dioxide cell
  • 1.5 V for the zinc-air cell, see zinc-air battery
  • 1.5 V for the lithium iron sulfide cell, see lithium iron sulfide battery
  • 1.55 V for the silver oxide-zinc cell, see silver oxide-zinc battery
  • 2.0 V for the lead dioxide lead cell (see lead accumulator)
  • 2.9 to 3.7 V for lithium cells, depending on the cathode material, see lithium battery or lithium accumulator

Nominal value of the mains voltage

In Europe the nominal value of the mains alternating voltage is 230 (outer conductor / earth, single-phase alternating current) or 400 volts (outer conductor / outer conductor, three-phase current). That is the rms value. The nominal value of the frequency is 50 Hz. Until 1987[1] the nominal value was 220 volts in continental Europe and 240 volts in the United Kingdom[2]. Electrical consumers specified for 220 V can usually also be operated at the 4.5% higher voltage. The energy consumption with unregulated linear consumers does not increase by 4.5% but by a little more than 9% because of the quadratic dependency.

In the USA, the nominal value of the AC mains voltage is 117 volts. This is the effective value (RMS). For larger consumers such as air conditioning systems, 240 V are also used. The nominal frequency is 60 Hz.
The often quoted 120 volts are rounded values.

Historically, the 110 and 220 volts go back to the fact that just 55 volts DC is sufficient for the operation of carbon arc lamps (street lighting, film projectors). At higher voltages there is a risk of electric shock and power would have been unnecessarily lost in the necessary series resistance of the arc lamps. By doubling it twice, you got 110 and 220 volts. The motivation for this was lower line losses or greater distances to be bridged with increasing consumption. This also meant that transformers were needed to set up the power grid, and the DC voltage that was initially used was switched to AC voltage. The incandescent lamps introduced in the meantime did not care whether direct or alternating voltage was applied, but alternating voltage can also be switched better.

Other nominal voltages

Vehicles and planes

  • 6 volts alternating voltage (bicycle dynamo, variable frequency, rated load 3 watts)
Motor vehicles (DC voltage)
  • 6 volts (older cars, motorcycles)
  • 12 volts (car, end-of-charge voltage and thus the on-board voltage is 14 volts)
  • 24 volts (truck, end-of-charge voltage and thus the on-board voltage is 28 volts), so-called automotive-Tolerance range is 18 ... 30 volts
Airplanes (selection)[3]
  • 28 volts DC voltage (22 ... 29 volts)
  • 115/200 volts three-phase current / 400 Hz (108 ... 118 volts RMS)
  • ± 270 volts direct voltage (250 ... 280 volts)
Railway vehicles
  • 24 V DC voltage (mainly railcars, tolerance range is 16.8 ... 30 V) [4]
  • 36 volts DC voltage (previously used in Switzerland for all vehicles control voltage)
  • 74 volts DC voltage (control voltage for American vehicles)
  • 110 volts DC voltage (mainly locomotives, tolerance range is 77 ... 137.5 V) [4]
  • 1000 volts AC / 16.7 Hz (train busbar)

Control voltages

Direct voltage (DC) or alternating voltage (AC) is used as control and operating voltage within electrical systems.

Industrial plants

Usual nominal voltages: 24 V DC, 24 V AC, 42 V AC.


Voltages of 100 V AC (output voltage from voltage converters), 110 V AC or DC, 220 V AC or DC are common.


  • Telephone terminal connection: 60 V DC voltage
  • Switching systems: 48 V DC voltage (operating voltage)
  • Tube output stages from large transmitters: 12 kV DC voltage

Energy distribution networks

Low voltage (<1kV)

  • 115 volts
  • 230 volts
  • 400 volts
  • 500 volts
  • 690 volts

Medium voltage (1kV - 35kV)

  • 6 kV
  • 10 kV
  • 15 kV (also standard voltage of the overhead line of electric railways of the DB, SBB and ÖBB)
  • 20 kV
  • 30 kV

Since numerous older underground cables (mostly for 6 kV and 10 kV) have been laid in many cities, the lower values ​​are common in many city networks. In rural areas, 20 kV and 30 kV are mostly used.

High voltage

  • 60 kV (in Germany almost only in city networks with a high proportion of older cables)
  • 66 kV (nominal voltage in the SBB traction network)
  • 110 kV (also rated voltage in the traction network in Germany and Austria)
  • 132 kV (nominal voltage in the SBB traction network)

High voltage

(→ Voltage specifications for high-voltage lines)

  • 220 kV / 230 kV (since the 1920s)
  • 380 kV / 400 kV (since 1952 Harsprånget - Hallsberg in Sweden, 1957 in Germany)

Other nominal voltages are sometimes used abroad. In other countries there are often relatively short test leads. Frequent values ​​in foreign high and extra high voltage networks are

  • 66 kV
  • 132 kV
  • 275 kV
  • 345 kV
  • 420 kV
  • 500 kV
  • 735 kV (since 1965 in Québec, Canada)
  • 750 kV (since the 1980s in Russia and from there to neighboring countries)
  • 765 kV (since 1967, mainly Russia, USA, Canada, South Africa, Brazil)
  • 1100 kV (three-phase line Kita-Iwaki in Japan, currently operated with 500 kV)
  • 1150 kV (three-phase line Ekibastus – Kökschetau in Russia, mostly operated with about half)

There are no nominal voltages for HVDC systems as there are almost always two-point connections. Frequently selected voltage values ​​for modern systems are:

  • 400 kV
  • 450 kV
  • 500 kV
  • 600 kV (from Itaipú to the greater São Paulo area)
  • 800 kV (HVDC Yunnan-Guangdong)

See also

  • Country overview plug types, line voltages and frequencies
  • Rated current
  • rated capacity

Web links / individual references

  1. ↑ http: //www.vattenfall.de/de/distribution/versorgungsqualitat-berlin.htm
  2. ↑ http: //www.soundlight.de/techtips/netzspg.htm
  3. ↑ http: //www.wbdg.org/ccb/FEDMIL/std704f.pdf MIL-STD-704F Aircraft Electric Power Characteristics
  4. 4,04,1EN 50155 (standard for electronic equipment on rail vehicles)