Why is k in lowercase for voltage kV, Do you know the reasons for V and A in kV and kVA?

Why is voltage kV in lowercase for k?

The units of measurement in international standards are generally in lowercase. Only when it comes to units named by name, such as Volt V, Ampere A, Kelvin K, Watt W, etc., in order to show respect for the predecessors of scientists, capital letters are used, while other units not named by personal names are generally used in lowercase. This explains why V is capitalized.

Secondly, for quantifiers, the initial order of magnitude is generally in lowercase. If the same letter is used, capitalization often distinguishes different orders of magnitude, such as m Ω M Ω, lowercase m represents 1 × 10-3; And capital M represents 1x106. So here, k represents 1 × 103. It should be in lowercase. (Perhaps this lowercase k is still used to distinguish it from K (Kelvin). Overall, it can be found that kV should be lowercase k, V capitalized.

For this question, you can actually understand it in capital letters, mainly from an academic perspective, how to use it in national standards, we need to write according to the standards.

Senior Electrical Scientist

Volt V

Alexandro Volta, a famous Italian physicist, was famous for inventing the "Volta stack" in 1800. On March 5, 1827, Volta passed away at the age of 82. In memory of him, people named the unit of electromotive force the volt.

Ampere A

Andre Marie Ampere was a famous French physicist, chemist, and mathematician. Ampere made remarkable achievements in the study of electromagnetic effects from 1820 to 1827, and was hailed as the "Newton of electricity". In commemoration of him, the international unit of electric current was named after his surname.

The standard symbol of the unit of measurement should be correct

The capitalization of letters cannot be arbitrary. Like A V. W, kV, kW, kVA, kvar, lx, km, etc. should all use legal measurement units, and special attention should be paid to the correct capitalization of unit symbol letters. For unit symbols converted from personal names, such as A V. W, N, Pa, and prefixes above megabytes such as M G should be capitalized; Otherwise, all lowercase characters are used, such as kV MW, kvar, km, etc. For information on measurement units, please refer to Chapter 16, pages 773-783 of the Industrial and Civil Power Distribution Design Manual. On November 16, 2018, the 26th International Conference on Weights and Measures passed a resolution to revise the International System of Units, officially updating the four basic unit definitions, including the International Standard Mass Unit "kilogram". The new International System of Units redefines the mass unit "kilogram", the current unit "ampere", the temperature unit "Kelvin", and the quantity unit of matter "mole" using physical constants.

Kelvin K

Kelvin, originally named William Thomson, was a famous British physicist who was awarded the title of Lord Kelvin by the Queen of England for his scientific achievements and contributions to the Atlantic cable project. He later changed his name to Kelvin and established an absolute temperature scale, resetting the melting point of water to 273.7 degrees; The boiling point is 373.7 degrees. To commemorate his contribution, the unit of absolute temperature is Kelvin (Kelvin, K) Name it.

Watt W

James Watt, an English inventor and an important figure in the First Industrial Revolution. The first steam engine with practical value was manufactured in 1776. After a series of significant improvements, it became a "universal prime mover" and was widely used in industry. He opened up a new era of energy utilization for humanity, ushering in the "steam age". In memory of this great inventor, later generations designated the unit of power as "watt" (abbreviated as "watt", symbol W).

Expansion: Basic Terminology of Electric Power

voltage

Voltage, also known as potential difference or potential difference, is a physical quantity that measures the energy difference generated by a unit charge in an electrostatic field due to different levels of potential. This concept is similar to the "water pressure" caused by high and low water levels. Voltage is the reason for the directional movement of charges to form current. The reason why current can flow in a wire is also because there is a difference between high potential and low potential in the current. This difference is called potential difference, also known as voltage. In other words. In a circuit, the potential difference between any two points is called the voltage between these two points. The letter U is usually used to represent voltage. The unit is volts (V), abbreviated as volts, represented by the symbol V as 1kV=1000V; Note: The voltage unit is kV (k in lowercase, V capital)

current

The amount of charge passing through a cross-section per unit time is called current. Due to the presence of voltage (potential difference), an electric field strength is generated, causing the charges in the circuit to move in a directional direction under the action of the electric field force, thereby forming the current in the circuit.

Usually represented by the letter I, the unit is A (ampere), with A (ampere), KA (kiloamperes), MA (milliampere); 1kA=1000A, 1A=1000mA.

Note: Unit kA, In mA, k. M is lowercase, A capitalized

Electricity level

Physically, electric quantity represents the amount of charge an object carries. We refer to the amount of electrical energy used by electrical equipment or users, also known as electrical energy or electrical work, which is the cumulative value of power over a certain period of time. Unit: kilowatt hour kW · h, megawatt hour MW · h. Note: Unit kWh (k in lowercase, W capital, H lowercase), MWh (uppercase M, W capital, H lowercase)

Direct current

Direct Current (DC) refers to the current that does not undergo periodic changes in direction and time, but its magnitude may not be fixed, resulting in a waveform. Also known as constant current. Generally, in dry batteries, the current in the battery is DC.

alternating current

AC current refers to a type of current whose magnitude and direction undergo periodic changes over time. In the power generation, transformation, distribution, and marketing processes of the power system, most of the electricity used is AC.

power

Power refers to the amount of work done by an object per unit of time, which is a physical quantity that describes the speed of work done. The amount of work is fixed, and the shorter the time, the greater the power value. The formula for calculating power is power=work/time.

Unit: W (uppercase English letter W)

KW (k in lowercase, W is capitalized)

MW (all uppercase letters)

1MW=1000kW

1kW=1000W.

Active power

It refers to the electrical power required to maintain the normal operation of electrical equipment, that is, the electrical power that converts electrical energy into other forms of energy (mechanical energy, light energy, thermal energy); Or the power consumed by the pure resistor part of the circuit, in watts. For example, a 5.5 kW electric motor converts 5.5 kW of electrical energy into mechanical energy to drive a water pump or thresher to thresh; various lighting equipment converts electrical energy into light energy for people's daily life and work lighting. The symbol for active power is represented by P.

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

Note: Unit W (in capital letters), KW (k in lowercase, W capital), MW (M, W is all capitalized)

Reactive power

When alternating current passes through a pure resistor, all electrical energy is converted into thermal energy, consuming active power. However, when passing through a pure capacitive or purely inductive load, no work is done, and the consumed power is reactive power. Reactive power is the electrical power used to exchange electric and magnetic fields within a circuit, and to establish and maintain magnetic fields in electrical equipment. It does not work externally, but transforms into other forms of energy. Any electrical equipment with electromagnetic coils must consume reactive power in order to establish a magnetic field. For example, a 40 watt fluorescent lamp requires not only more than 40 watts of active power (which the ballast also consumes) to emit light, but also about 80 reactive power to establish an alternating magnetic field in the coil of the ballast. It is called "reactive" because it does not work externally. The symbol of reactive power is represented by Q, in units of var or kvar Reactive power is by no means useless power, it is of great use. The rotor magnetic field of an electric motor is established by obtaining useless power from the power source. Transformers also require reactive power in order to generate a magnetic field in the primary coil and induce voltage in the secondary coil. Therefore, without reactive power, the motor will not rotate, the transformer will not change voltage, and the AC contactor will not engage. To illustrate the problem vividly, let me give an example: rural water conservancy requires excavation and soil transportation. When transporting soil, bamboo baskets are used to fill the soil. The picked soil is like active power, while empty bamboo baskets are like reactive power. Bamboo baskets are not useless. How can soil be transported to the embankment without bamboo baskets?

Note: Unit var (v, a. R is all lowercase), Kvar (k lowercase, V lowercase, A lowercase, R lowercase).

Apparent power

In the power network, the product of voltage and current is called apparent power, represented by S, and S=UI. When all the loads in the network are pure resistors, the apparent power is equal to the active power. Usually, due to the presence of inductive or capacitive loads in the power grid, the apparent power is greater than the active power. To show differentiation, the apparent power is not measured in watts (W), but in volts amperes (VA) or kilovolts amperes (kVA). In the power system, apparent power reflects the capacity of equipment, and the product of rated voltage and rated current of electrical equipment is the capacity of that equipment.

Note: The unit of apparent power is VA (V), A is all capitalized), KVA (k lowercase, V. A in uppercase)