# Do you know why k is lower case for kV voltage?

2023-03-18Archive

Why is k for kV in lower case? Units of measurement in international standards are usually written in lowercase letters. Only when referring to units named after names such as volt V, ampere A, kelvin K, watt, watts, etc. named after people, usually written in lower case< /strong>. That's why V is capitalized.

Second, for quantifiers, initial value is usually lowercase. If letters are same, uppercase and lowercase often distinguish between different orders of magnitude, such as mΩ, MΩ, lowercase m means 1x10^-3, and uppercase M means 1x10^6. Therefore, k here means 1×10^3 and must be lowercase. (Perhaps this lowercase k is still different from K (Kelvin)) So one might find that kV must be a lowercase k and an uppercase V.

Actually, even if it's all capitalized, people can understand it. From an academic point of view, how to use national standard, we must write according to the standard.

Senior Electrical Scientist Volt

Alessandro Volta, famous Italian physicist, became famous for inventing "voltaic pole" in 1800. On March 5, 1827, Volta died at age of eighty-two. The unit of electromotive force was named volt after him. Ampere A

André Marie Ampère, famous French physicist, chemist and mathematician. The ampere made outstanding progress in study of electromagnetic interaction from 1820 to 1827 and was known as "Newton in electricity", after which international unit of current is named. Kelvin K.

Kelvin, formerly known as William Thomson, a famous British physicist, was awarded title of Lord Kelvin by Queen of England for his scientific achievements and contributions to Atlantic cable project, so subsequent generations changed his name to Kelvin. absolute temperature scale and reset melting point of water to 273.7 degrees, boiling point to 373.7 degrees. In honor of his contribution, unit of absolute temperature is named Kelvin (K). Watt W

James Watt, a British inventor, played an important role in first industrial revolution. In 1776 first practical steam engine was made. After a number of major improvements, he became a "universal tractor" and was widely used in industry. He opened a new era of energy use by people and led people into "age of steam". To commemorate this great inventor, later generations established unit of power as "watt" (abbreviated "watt", symbol W).

• Voltage

• Voltage, also known as potential difference or potential difference, is a physical quantity that measures difference in energy of a unit charge in an electrostatic field due to a potential difference. This concept is similar to "water pressure" caused by high and low water levels. Voltage is what controls directional movement of charges to form an electric current. The reason current can flow in a wire is also because there is a difference between high potential and low current potential. This difference is called potential difference, also called voltage.

In other words, in a circuit, potential difference between any two points is called voltage at those two points. The letter U is usually used to represent voltage. The unit of measurement is volt (V), denoted as volt, denoted by symbol V 1 kV = 1000 V;

Note. The unit of voltage is kV (lowercase k, uppercase V)

• Current

• The amount of charge passing through cross section per unit time is called current. Due to presence of voltage (potential difference), an electric field strength is created so that charges in circuit are subjected to force of electric field to create a directional movement, thus generating a current in circuit.

Usually denoted by letter I, unit is A (amps), including A (amps), kA (kiloamps), mA (milliamps); 1 kA = 1000 A, 1 A = 1000 mA.

Note. In kA and mA, k and m are written in lowercase letters, and A in capital letters

• Battery

• Physically, electricity means how much charge an object has. Here we represent amount of electricity used by electrical equipment or users, also known as electrical energy or electrical work, which is cumulative value of power over a period of time.

Unit of measurement: kilowatt-hour kWh, megawatt-hour MWh.

Note: unit kWh (k lower case, W upper case, h lower case), MWh (M upper case, W upper case, h lower case)

• Forward current

• Direct current (DC for short) refers to a current whose direction and time do not periodically change, but magnitude of current may not be fixed, and waveform is generated. Also known as direct current. As a rule, dry batteries, current in battery is constant.

• Alternating current

• Alternating current refers to a type of current whose magnitude and direction change periodically over time. In power generation, power conversion, power distribution and marketing links in power system, most of them use alternating current.

• Power

• Power refers to work done by an object per unit of time, so power is a physical quantity that describes speed of work. The amount of work is defined, shorter time, greater the power value. Power formula: power = work / time.

Unit: W (capital English letter W)

kW(k - lowercase, W - uppercase)

MW (all caps)

1 MW=1000 kW

1kW=1000W.

• Active power

• refers to electricity needed to keep electrical equipment running properly, i.e. electricity that converts electrical energy into other forms of energy (mechanical energy, light energy, thermal energy); or power consumed by pure resistance of a part of a circuit, unit is W. (For example: a 5.5 kilowatt motor converts 5.5 kilowatts of electrical energy into mechanical energy to drive water pumps or threshing machines for threshing; various lighting equipment converts electrical energy into light energy for people's life and work. The active power symbol is presented by author P .

Units: watts (W), kilowatts (kW), megawatts (MW). )

Note. Unit W (capital letters), kW (k lower case, W upper case), MW (M, W upper case)

• Reactive power

• When an alternating current passes through a pure resistance, electrical energy is converted into heat energy and consumes active power, but when it passes through a purely capacitive or purely inductive load, it does no work and power consumed is reactive power.

Reactive power is electrical power used to exchange an electric field and a magnetic field in a circuit, and to create and maintain a magnetic field in electrical equipment. It does not work outside, but is transformed into other forms of energy.

Any electrical equipment with electromagnetic coils must consume reactive power to create a magnetic field. (For example: a 40 watt fluorescent lamp needs more than 40 watts of active power to emit light (the ballast must also consume some of active power), as well as about 80 watts of reactive power for ballast coil to create an alternating magnetic field. . Because it does no external work, it is called "reactive work". The reactive power symbol is represented by letter Q and unit is var (var) or kvar (kvar). )

Reactive power is not useless power, it is very useful. The magnetic field of motor rotor is created by obtaining useless power from power supply.

The transformer also needs reactive power in order for primary winding of transformer to generate a magnetic field and induce a voltage in secondary winding. Therefore, without reactive power, motor will not rotate, transformer will not change voltage, and AC contactor will not pull in.

To illustrate problem, here's an example: building a reservoir in a rural area requires digging and transporting soil. When transporting soil, bamboo baskets are filled with soil. The lifted soil is like an active force, and lifting empty bamboo baskets is like reactive power, bamboo baskets are not useless, how can soil be transported to embankment without bamboo baskets?

Note. The unit is var (v, a, r - all lowercase), kvar (k - lowercase, v - lowercase, a - lowercase, r - lowercase).

• Full Power

• In electrical network, product of voltage and current is called apparent power and is denoted by letter S, and S=UI. When all loads in network are pure resistance, apparent power is equal to active power. Usually, due to presence of inductive or capacitive loads in network, apparent power is greater than active power.

To show difference, unit of apparent power is not watt (W), but volt-ampere (VA) or kilovolt-ampere (kVA). In power system, apparent power reflects power of equipment, and product of rated voltage and rated current of electrical equipment is power of equipment.

Note: Apparent power unit VA (V, A uppercase), kVA (k lowercase, V, A uppercase)