About lightning protection and the application of voltage, current symbols

The main parameters of the arrester.

1. Nominal voltage UN: the rated voltage of the protected system is consistent, and this parameter indicates the type of protector that should be selected in the information technology system, and it indicates the effective value of AC or DC voltage.

2. Rated voltage UC: the maximum effective voltage value that can be applied to the designated end of the protector for a long time without causing the change of the characteristics of the protector and activating the protection element.

3. Rated discharge current isn: the maximum peak value of the impulse current tolerated by the protector when the standard lightning wave with a waveform of 8 20 s is applied to the protector for 10 times.

4. Maximum discharge current imax: the maximum impulse current peak that the protector can withstand when the standard lightning wave with a waveform of 8 20 s is applied to the protector for one time.

5. Voltage protection level UP: the maximum value of the protector in the following tests: the flashover voltage of 1kV s slope; The residual voltage of the rated discharge current.

6. Response time ta: the action sensitivity and breakdown time of the special protection elements that mainly respond to the protector depend on the slope of du dt or di dt in a certain period of time.

7. Leakage current: refers to the DC current flowing through the protector at 75 or 80 nominal voltage UN.

Maximum continuous operating voltage uc

ac 385v

ac 385v

Limit voltage up

Nominal discharge current in (8 20 s).

40ka20ka

Maximum discharge current Imax (8 20 s).

80ka40ka

Response time. 25 ka rms

ns maximum back-up fuse strength.

125a back-up protection device rep-fb-

Wiring. Parallel connection.

Mounting bracket. 35mm wide electrical mounting rails.

Degree of protection. ip20

Install conductor sections.

Minimum 25mm2 stranded wire (L, N) Maximum 35mm2 stranded wire (PE, ) housing material. Enhanced flame retardant.

Dimensions. See overall dimension drawing.

Installation location. Installed in the distribution box, class C.

Reference standards. iec 61643，gb18802-2002，gb50343－2004

It is recommended for landlords to refer to it.

This standard is very detailed inside.

The symbol for current is i, the sign for voltage is u, and the symbol for power is p.

Current (i) Scientifically, the amount of electricity passing through any cross-section of a conductor per unit time is called current intensity, referred to as current. Usually denoted by the letter i, it is measured in amperes (a).

Voltage (u), also known as potential difference or potential difference, is a physical quantity that measures the difference in energy between a unit charge in an electrostatic field due to different potentials. Its magnitude is equal to the work done by a unit positive charge to move from point A to point B due to the action of an electric field force, and the direction of the voltage is specified as the direction from the high potential to the low potential. The SI system of units for voltage is volts (V, abbreviated as volts).

Power (p) is a physical quantity that describes how fast or slow work is done. The amount of work is constant, and the shorter the time, the greater the power value. The work done per unit of time is called power and is denoted by p.

The current is represented by i in a (ampere), and the SI unit of electric current, the ampere, is named after its surname), abbreviated as "ampere", and the symbol "a", which also refers to the directional movement of an electric charge in a conductor.

Voltage is expressed in U in V (volts), and in order to generate current in a circuit, there must be voltage at both ends of it. The function of the power supply is to provide voltage to both ends of the electrical appliance.

Power is expressed in p and the unit is w (watts), and power can be divided into electrical power, power of force, etc. Therefore, the calculation formula is also different.

The symbol for current is i, the sign for voltage is u, and the symbol for power is p.

Current, also known as current intensity, refers to the amount of electricity that passes through any cross-section of a conductor per unit of time. It is usually denoted by the letter i and is measured in amps.

Voltage, also known as potential difference or potential difference, is a physical quantity that measures the energy difference between a unit charge in an electrostatic field due to different electric potentials. It is usually denoted by the letter U and is measured in volts.

Power, power, refers to the amount of work done by an object per unit of time, which is used to describe how fast or slow the work is done. It is usually denoted by the letter p and is measured in watts.

The formula between the three is: p = u*i.

Current is expressed in i in a (amps), voltage is expressed in u in v (volts), and power is expressed in p in w (watts).

Current: The unit is amperes (a), and "i" is used as the code;

Voltage: The unit is volts (V), and "U" is used as the code;

Power: The unit of active power is watts (W), and "P" is used as the code;

The unit of reactive power is var, and "Q" is used as the code;

The apparent unit of power is volt-ampere (VA), and the code is indicated by "S".

Current: Indicated by "i" in amperes (a).

Voltage: Expressed using "U" in volts (V).

Power: Expressed using "P" in watts (W).

The current is i and the voltage is u and the symbol for electric power is p

Die** deliberately make so many points to ask such a retarded question grass.

AC voltage or current is a phasor, and the so-called phasor is a quantity that has a magnitude, direction, and changes with time.

With a point to represent the phasor operation, the result is the total quantity such as magnitude and direction;

What does not have a point is the operation of the modulus, without the change of direction and time.

Voltage, symbol is u, unit volts resistance, symbol is r, unit ohm current, symbol is i, unit ampere to adopt.

1. Resistance symbol:

r in ohm or ohm).

2. Current symbol: i, unit: a (ampere).

3. Voltage symbol: U, unit: V (volts).

4. Power symbol: P, unit: W (watts).

The first person in the world to systematically study the relationship between current, voltage and resistance was Ohm (1789 1854). On the basis of a large number of experiments, Ohm summed up the relationship between the three: when the voltage is constant, the current is inversely proportional to the resistance; When the resistance is constant, the current is proportional to the voltage, which is expressed by the formula:

i=u/r。

Voltage, symbol is U, unit volt resistance, symbol is r, unit ohmic current, symbol is i, unit ampere.

AC voltage gear: ACV

DC voltage range: DCV

AC resistance level, DC resistance level, multimeter can only measure DC resistance, and the gear indication is: AC current level: ACA

DC current gear: DCA

The symbol of the rated current is not in, but the melt rating of the fuse. Rated current = rated power Rated voltage (i=p u).

The rated current is calculated by dividing the rated capacity of the winding by the rated voltage of the winding and the corresponding coefficient (1 for single phase and 3 for three phase). Therefore, the rated current of the transformer is the rated current of each winding.

If the power supply is on the left side, the upper end must be positive according to the direction of the current; In order for the two bulbs to be connected in series, the right end must be an ammeter; Therefore, it is a voltmeter; meet the requirements; As shown in the figure below:

If the power supply is on the right side, the lower end must be positive according to the direction of the current; In order for the two bulbs to be connected in series, the left end must be an ammeter; Therefore, the middle is a voltmeter; Comply with the requirements of letting sell; As shown in the figure below:

If there is a power supply in the middle, it is not possible to make the two bulbs in series, so it does not meet the topic <>