What is the direct impact of voltage on the safe operation of various types of electrical equipment?

The voltage is to make the current move in a directional way, and with the current can the electrical appliances operate, and the electrical appliances have a certain rated voltage, and the working voltage that exceeds the rated value will cause the primary side of the electrical appliances to overheat, thereby reducing the service life or directly burning the electrical appliances. If the current and voltage are too high, there is a danger of burning out the electrical appliances, and if the current and voltage are too low, it will cause the electrical appliances to not work normally and reduce the service life of the electrical appliances. Electric current refers to the flow of a group of electric charges.

The magnitude of the current is called the current intensity, which refers to the amount of charge passing through a certain section of the wire per unit time, and the amount of electricity passing through one coulomb per second is called one ampere. The ampere is a basic unit in the International System of Units. An ammeter is an instrument that specializes in measuring electric current.

Nature has many kinds of charge-loaded carriers, for example, electrons that can move in a conductor, ions in an electrolyte, electrons and ions in a plasma, quarks in hadrons. Voltage, 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 unit system of voltage is volts (V, referred to as volts), and the commonly used units are millivolts (mV), microvolts (V), kilovolts (kv), etc. This concept is related to the level of water"Water pressure"Similar. It should be noted that"Voltage"The term is generally only used in electrical circuits"Potential difference"with"Potential difference"It is widely used in all electrical phenomena.

Frequency, which is the number of times a periodic change is completed per unit of time, is a quantity that describes the frequency of periodic motion, and is usually represented by the symbol f or , the unit is one second and the symbol is s. In honor of the contribution of the German physicist Hertz, the unit of frequency was named Hertz, or short"Hey"with the symbol Hz. Every object has an amplitude-independent frequency that is determined by its own properties, called natural frequencies.

The concept of frequency is used not only in mechanics and acoustics, but also in electromagnetics, optics and radio technology.

Each electrical device has its own rated voltage. If the supply voltage exceeds the rated voltage, the current passing through the appliance will increase and the appliance will be burned. If the power supply voltage is too high, it will cause a safety accident if it exceeds the tolerance limit of the insulation material on the appliance.

On the contrary, if the power supply voltage is too low, the electrical appliances will not work normally or at all, such as the brightness of the bulb will become low, the speed of the motor will be reduced, etc. FYI.

The voltage required for the normal operation of any electrical equipment is certain, called the rated voltage of the electrical appliance, if the power supply voltage exceeds the rated voltage, the electrical appliance is easy to be burned out, if the power supply voltage is lower than the rated voltage, the electrical appliance can not work normally, or can not work.

The safety voltage of electrical equipment is specified at 36V.

The safe voltage is the voltage that does not directly cause death or disability, and the "safe extra low voltage" that allows continuous contact under normal environmental conditions is 36V. The industry stipulates that the safety voltage is not higher than 36V, the continuous contact safety voltage is 24V, and the safety current is 10mA. The degree of harm to the human body of electric shock mainly depends on the size of the current passing through the human body and the length of the power on time.

The greater the current intensity, the greater the fatal danger; The longer it lasts, the more likely it is to die. The minimum value of current that can be perceived by a person is called the perceived current, which is 1 mA for AC and 5 mA for DC; The maximum current that a person can get rid of after an electric shock is called getting rid of the current, which is 10mA for AC and 50mA for DC; The life-threatening current in a relatively short period of time is called a lethal current, and it is known that a current of 100 mA passes through the human body for 1s, which is enough to make a person talk about being buried, so the lethal current is 50 mA. In the case of protection against electric shock, the current allowed by the human body can generally be considered as 30mA.

In general, safe voltages should be used in environments with a high risk of electric shock and in particularly humid places.

The safety voltage in our country is 42V, 36V, 24V, 12V, 6V

Portable lighting, general lighting with insufficient height, portable power tools, etc., if there is no special safety structure and measures, the safety voltage is 36V

The working place is narrow, difficult to move and there is a large area of grounding and other environments (such as metal containers, tunnels, mines), and the safety voltage is 12V

Answer] :d This question examines the safety technology of electrical installation. Class III equipment relies on a safe ultra-low voltage power supply to prevent electric shock, and a voltage higher than the safety ultra-low voltage in the Class III equipment must not be generated.

The following is correct for the use of safe voltages: ().

a.All portable power tools used in particularly hazardous environments should use a safe voltage of 42V (correct answer).

b.All hand-held lights and local lights used in environments where there is a risk of electric shock should use 12V safety liquid holding voltage.

c.There is a narrow skin grinding in metal containers, tunnels, wells and around large areas of grounding conductors, and the environment with limited mobility should use a safe voltage of 12V (correct answer).

d.The machine lighting should use a safe voltage of 12V.

e.Special places such as water operations should use a safe voltage of 6V (correct answer).

The following points need to be paid attention to in the safe use of electricity:

1. Do not repair or tremble the live lines or equipment in your home, such as fans, washing machines, televisions, etc., to avoid electric shock;

2. Do not use metal to touch electricity, do not touch the power supply with wet hands, and do not use a wet cloth to wipe lamps, switches and other electrical appliances;

3. Install the three-pin socket correctly, and do not change the three-prong plug to a two-prong plug at will;

4. Use the power cord correctly, and do not pull or connect the wires indiscriminately;

5. Do not add electrical appliances to the original line without permission;

6. Correct use of household appliances, and shall not use electrical equipment that does not meet safety specifications;

7. Develop good habits, in the case of unattended or long-term non-use, please unplug the power supply of electric irons, hair dryers, electric stoves and other electrical appliances;

8. It is forbidden to use lead wire, copper wire and other substitute fuse wires as fuses;

9. Use leakage protectors to prevent the occurrence of electric shock and electrical fire.

We hope you find ours helpful.